[RFC,v2,1/1] drm: allow to use mmuless SoC

Message ID 1480511958-10266-1-git-send-email-benjamin.gaignard@linaro.org
State New
Headers show

Commit Message

Benjamin Gaignard Nov. 30, 2016, 1:19 p.m.
Some SoC without MMU have display driver where a drm/kms driver
could be implemented.
Before doing such kind of thing drm/kms must allow to use mmuless
devices.
This patch propose to remove MMU configuration flag and add some
cma helpers functions to help implementing mmuless display driver

version 2:
- define get_fb_unmapped_area() in drivers/video/fbdev/core/fbmem.c
  if HAVE_ARCH_FB_UNMAPPED_AREA is set and get_fb_unmapped_area not
  already defined in the architecture

Signed-off-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>
---
 drivers/gpu/drm/Kconfig              |  4 +--
 drivers/gpu/drm/drm_fb_cma_helper.c  |  4 +++
 drivers/gpu/drm/drm_gem_cma_helper.c | 62 ++++++++++++++++++++++++++++++++++++
 drivers/gpu/drm/drm_vm.c             |  4 +++
 drivers/video/fbdev/core/fbmem.c     | 15 +++++++++
 include/drm/drm_gem_cma_helper.h     |  6 ++++
 6 files changed, 93 insertions(+), 2 deletions(-)

Comments

Laurent Pinchart Nov. 30, 2016, 1:27 p.m. | #1
Hi Benjamin,

Thank you for the patch.

On Wednesday 30 Nov 2016 14:19:18 Benjamin Gaignard wrote:
> Some SoC without MMU have display driver where a drm/kms driver
> could be implemented.
> Before doing such kind of thing drm/kms must allow to use mmuless
> devices.
> This patch propose to remove MMU configuration flag and add some
> cma helpers functions to help implementing mmuless display driver
> 
> version 2:
> - define get_fb_unmapped_area() in drivers/video/fbdev/core/fbmem.c
>   if HAVE_ARCH_FB_UNMAPPED_AREA is set and get_fb_unmapped_area not
>   already defined in the architecture
> 
> Signed-off-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>
> ---
>  drivers/gpu/drm/Kconfig              |  4 +--
>  drivers/gpu/drm/drm_fb_cma_helper.c  |  4 +++
>  drivers/gpu/drm/drm_gem_cma_helper.c | 62 +++++++++++++++++++++++++++++++++
>  drivers/gpu/drm/drm_vm.c             |  4 +++
>  drivers/video/fbdev/core/fbmem.c     | 15 +++++++++
>  include/drm/drm_gem_cma_helper.h     |  6 ++++
>  6 files changed, 93 insertions(+), 2 deletions(-)

[snip]

> diff --git a/drivers/video/fbdev/core/fbmem.c
> b/drivers/video/fbdev/core/fbmem.c index 76c1ad9..54488ee 100644
> --- a/drivers/video/fbdev/core/fbmem.c
> +++ b/drivers/video/fbdev/core/fbmem.c
> @@ -1492,6 +1492,21 @@ static long fb_compat_ioctl(struct file *file,
> unsigned int cmd, return 0;
>  }
> 
> +#if defined(HAVE_ARCH_FB_UNMAPPED_AREA) && !defined(get_fb_unmapped_area)

Only blackfin and sparc define HAVE_ARCH_FB_UNMAPPED_AREA, and both of them 
provide an implementation of get_fb_unmapped_area().

> +unsigned long get_fb_unmapped_area(struct file *filp,
> +				    unsigned long addr, unsigned long len,
> +				    unsigned long pgoff, unsigned long flags)
> +{
> +	struct fb_info * const info = filp->private_data;
> +	unsigned long fb_size = PAGE_ALIGN(info->fix.smem_len);
> +
> +	if (pgoff > fb_size || len > fb_size - pgoff)
> +		return -EINVAL;
> +
> +	return (unsigned long)info->screen_base + pgoff;
> +}
> +#endif
> +
>  static const struct file_operations fb_fops = {
>  	.owner =	THIS_MODULE,
>  	.read =		fb_read,

[snip]
Daniel Vetter Dec. 1, 2016, 6:56 a.m. | #2
On Wed, Nov 30, 2016 at 02:19:18PM +0100, Benjamin Gaignard wrote:
> Some SoC without MMU have display driver where a drm/kms driver
> could be implemented.
> Before doing such kind of thing drm/kms must allow to use mmuless
> devices.
> This patch propose to remove MMU configuration flag and add some
> cma helpers functions to help implementing mmuless display driver
> 
> version 2:
> - define get_fb_unmapped_area() in drivers/video/fbdev/core/fbmem.c
>   if HAVE_ARCH_FB_UNMAPPED_AREA is set and get_fb_unmapped_area not
>   already defined in the architecture
> 
> Signed-off-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>
> ---
>  drivers/gpu/drm/Kconfig              |  4 +--
>  drivers/gpu/drm/drm_fb_cma_helper.c  |  4 +++
>  drivers/gpu/drm/drm_gem_cma_helper.c | 62 ++++++++++++++++++++++++++++++++++++
>  drivers/gpu/drm/drm_vm.c             |  4 +++
>  drivers/video/fbdev/core/fbmem.c     | 15 +++++++++
>  include/drm/drm_gem_cma_helper.h     |  6 ++++
>  6 files changed, 93 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
> index 8d9cf73..36c102b 100644
> --- a/drivers/gpu/drm/Kconfig
> +++ b/drivers/gpu/drm/Kconfig
> @@ -6,7 +6,7 @@
>  #
>  menuconfig DRM
>  	tristate "Direct Rendering Manager (XFree86 4.1.0 and higher DRI support)"
> -	depends on (AGP || AGP=n) && !EMULATED_CMPXCHG && MMU && HAS_DMA
> +	depends on (AGP || AGP=n) && !EMULATED_CMPXCHG && HAS_DMA
>  	select HDMI
>  	select FB_CMDLINE
>  	select I2C
> @@ -98,7 +98,7 @@ config DRM_LOAD_EDID_FIRMWARE
>  
>  config DRM_TTM
>  	tristate
> -	depends on DRM
> +	depends on DRM && MMU
>  	help
>  	  GPU memory management subsystem for devices with multiple
>  	  GPU memory types. Will be enabled automatically if a device driver
> diff --git a/drivers/gpu/drm/drm_fb_cma_helper.c b/drivers/gpu/drm/drm_fb_cma_helper.c
> index 81b3558..b1414b6 100644
> --- a/drivers/gpu/drm/drm_fb_cma_helper.c
> +++ b/drivers/gpu/drm/drm_fb_cma_helper.c
> @@ -343,8 +343,12 @@ int drm_fb_cma_debugfs_show(struct seq_file *m, void *arg)
>  
>  static int drm_fb_cma_mmap(struct fb_info *info, struct vm_area_struct *vma)
>  {
> +#ifdef CONFIG_MMU
>  	return dma_mmap_writecombine(info->device, vma, info->screen_base,
>  				     info->fix.smem_start, info->fix.smem_len);
> +#else
> +	return vm_iomap_memory(vma, vma->vm_start, info->fix.smem_len);
> +#endif
>  }
>  
>  static struct fb_ops drm_fbdev_cma_ops = {
> diff --git a/drivers/gpu/drm/drm_gem_cma_helper.c b/drivers/gpu/drm/drm_gem_cma_helper.c
> index 1d6c335..de13535 100644
> --- a/drivers/gpu/drm/drm_gem_cma_helper.c
> +++ b/drivers/gpu/drm/drm_gem_cma_helper.c
> @@ -318,11 +318,16 @@ static int drm_gem_cma_mmap_obj(struct drm_gem_cma_object *cma_obj,
>  	vma->vm_flags &= ~VM_PFNMAP;
>  	vma->vm_pgoff = 0;
>  
> +#ifdef CONFIG_MMU
>  	ret = dma_mmap_wc(cma_obj->base.dev->dev, vma, cma_obj->vaddr,
>  			  cma_obj->paddr, vma->vm_end - vma->vm_start);
>  	if (ret)
>  		drm_gem_vm_close(vma);
>  
> +#else
> +	ret = vm_iomap_memory(vma, vma->vm_start,
> +			      (vma->vm_end - vma->vm_start));
> +#endif

Ok, me asking for a separate helper was probably too much. The #ifdefs
here are still ugly, but on 2nd thought this just looks like the dma api
is broken on no-mmu? Shouldn't we instead have a patch somewhere which
gives us a working dma_mmap_wc on nommu platforms?

>  	return ret;
>  }
>  
> @@ -358,6 +363,63 @@ int drm_gem_cma_mmap(struct file *filp, struct vm_area_struct *vma)
>  }
>  EXPORT_SYMBOL_GPL(drm_gem_cma_mmap);
>  
> +#ifdef CONFIG_MMU
> +#define drm_gem_cma_get_unmapped_area NULL

Depending upon how it's used it might be better to stub it out ...

> +#else
> +unsigned long drm_gem_cma_get_unmapped_area(struct file *filp,
> +					    unsigned long addr,
> +					    unsigned long len,
> +					    unsigned long pgoff,
> +					    unsigned long flags)

With no user and no kerneldoc I kinda have no idea what this is even for.
The name also doesn't help, it says "get_unmapped_area", but very clearly
you're returning a kernel vaddr cast to a  long (and with ERR_PTR
semantics on top, but non-standard). Why is this not called get_vaddr?
-Daniel

> +{
> +	struct drm_gem_cma_object *cma_obj;
> +	struct drm_gem_object *obj = NULL;
> +	struct drm_file *priv = filp->private_data;
> +	struct drm_device *dev = priv->minor->dev;
> +	struct drm_vma_offset_node *node;
> +
> +	if (drm_device_is_unplugged(dev))
> +		return -ENODEV;
> +
> +	drm_vma_offset_lock_lookup(dev->vma_offset_manager);
> +	node = drm_vma_offset_exact_lookup_locked(dev->vma_offset_manager,
> +						  pgoff,
> +						  len >> PAGE_SHIFT);
> +	if (likely(node)) {
> +		obj = container_of(node, struct drm_gem_object, vma_node);
> +		/*
> +		 * When the object is being freed, after it hits 0-refcnt it
> +		 * proceeds to tear down the object. In the process it will
> +		 * attempt to remove the VMA offset and so acquire this
> +		 * mgr->vm_lock.  Therefore if we find an object with a 0-refcnt
> +		 * that matches our range, we know it is in the process of being
> +		 * destroyed and will be freed as soon as we release the lock -
> +		 * so we have to check for the 0-refcnted object and treat it as
> +		 * invalid.
> +		 */
> +		if (!kref_get_unless_zero(&obj->refcount))
> +			obj = NULL;
> +	}
> +
> +	drm_vma_offset_unlock_lookup(dev->vma_offset_manager);
> +
> +	if (!obj)
> +		return -EINVAL;
> +
> +	if (!drm_vma_node_is_allowed(node, priv)) {
> +		drm_gem_object_unreference_unlocked(obj);
> +		return -EACCES;
> +	}
> +
> +	cma_obj = to_drm_gem_cma_obj(obj);
> +
> +	drm_gem_object_unreference_unlocked(obj);
> +
> +	return cma_obj->vaddr ? (unsigned long)cma_obj->vaddr : -EINVAL;
> +}
> +#endif
> +EXPORT_SYMBOL_GPL(drm_gem_cma_get_unmapped_area);
> +
>  #ifdef CONFIG_DEBUG_FS
>  /**
>   * drm_gem_cma_describe - describe a CMA GEM object for debugfs
> diff --git a/drivers/gpu/drm/drm_vm.c b/drivers/gpu/drm/drm_vm.c
> index caa4e4c..974e02b 100644
> --- a/drivers/gpu/drm/drm_vm.c
> +++ b/drivers/gpu/drm/drm_vm.c
> @@ -489,6 +489,7 @@ static int drm_mmap_dma(struct file *filp, struct vm_area_struct *vma)
>  #if defined(__i386__) || defined(__x86_64__)
>  		pgprot_val(vma->vm_page_prot) &= ~_PAGE_RW;
>  #else
> +#ifdef CONFIG_MMU
>  		/* Ye gads this is ugly.  With more thought
>  		   we could move this up higher and use
>  		   `protection_map' instead.  */
> @@ -497,6 +498,7 @@ static int drm_mmap_dma(struct file *filp, struct vm_area_struct *vma)
>  			     (pte_wrprotect
>  			      (__pte(pgprot_val(vma->vm_page_prot)))));
>  #endif
> +#endif
>  	}
>  
>  	vma->vm_ops = &drm_vm_dma_ops;
> @@ -573,6 +575,7 @@ static int drm_mmap_locked(struct file *filp, struct vm_area_struct *vma)
>  #if defined(__i386__) || defined(__x86_64__)
>  		pgprot_val(vma->vm_page_prot) &= ~_PAGE_RW;
>  #else
> +#ifdef CONFIG_MMU
>  		/* Ye gads this is ugly.  With more thought
>  		   we could move this up higher and use
>  		   `protection_map' instead.  */
> @@ -581,6 +584,7 @@ static int drm_mmap_locked(struct file *filp, struct vm_area_struct *vma)
>  			     (pte_wrprotect
>  			      (__pte(pgprot_val(vma->vm_page_prot)))));
>  #endif
> +#endif
>  	}
>  
>  	switch (map->type) {
> diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c
> index 76c1ad9..54488ee 100644
> --- a/drivers/video/fbdev/core/fbmem.c
> +++ b/drivers/video/fbdev/core/fbmem.c
> @@ -1492,6 +1492,21 @@ static long fb_compat_ioctl(struct file *file, unsigned int cmd,
>  	return 0;
>  }
>  
> +#if defined(HAVE_ARCH_FB_UNMAPPED_AREA) && !defined(get_fb_unmapped_area)
> +unsigned long get_fb_unmapped_area(struct file *filp,
> +				    unsigned long addr, unsigned long len,
> +				    unsigned long pgoff, unsigned long flags)
> +{
> +	struct fb_info * const info = filp->private_data;
> +	unsigned long fb_size = PAGE_ALIGN(info->fix.smem_len);
> +
> +	if (pgoff > fb_size || len > fb_size - pgoff)
> +		return -EINVAL;
> +
> +	return (unsigned long)info->screen_base + pgoff;
> +}
> +#endif
> +
>  static const struct file_operations fb_fops = {
>  	.owner =	THIS_MODULE,
>  	.read =		fb_read,
> diff --git a/include/drm/drm_gem_cma_helper.h b/include/drm/drm_gem_cma_helper.h
> index acd6af8..177a20d 100644
> --- a/include/drm/drm_gem_cma_helper.h
> +++ b/include/drm/drm_gem_cma_helper.h
> @@ -53,6 +53,12 @@ struct drm_gem_cma_object *drm_gem_cma_create(struct drm_device *drm,
>  
>  extern const struct vm_operations_struct drm_gem_cma_vm_ops;
>  
> +unsigned long drm_gem_cma_get_unmapped_area(struct file *filp,
> +					     unsigned long addr,
> +					     unsigned long len,
> +					     unsigned long pgoff,
> +					     unsigned long flags);
> +
>  #ifdef CONFIG_DEBUG_FS
>  void drm_gem_cma_describe(struct drm_gem_cma_object *obj, struct seq_file *m);
>  #endif
> -- 
> 1.9.1
>
Benjamin Gaignard Dec. 1, 2016, 7:03 a.m. | #3
2016-12-01 7:56 GMT+01:00 Daniel Vetter <daniel@ffwll.ch>:
> On Wed, Nov 30, 2016 at 02:19:18PM +0100, Benjamin Gaignard wrote:
>> Some SoC without MMU have display driver where a drm/kms driver
>> could be implemented.
>> Before doing such kind of thing drm/kms must allow to use mmuless
>> devices.
>> This patch propose to remove MMU configuration flag and add some
>> cma helpers functions to help implementing mmuless display driver
>>
>> version 2:
>> - define get_fb_unmapped_area() in drivers/video/fbdev/core/fbmem.c
>>   if HAVE_ARCH_FB_UNMAPPED_AREA is set and get_fb_unmapped_area not
>>   already defined in the architecture
>>
>> Signed-off-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>
>> ---
>>  drivers/gpu/drm/Kconfig              |  4 +--
>>  drivers/gpu/drm/drm_fb_cma_helper.c  |  4 +++
>>  drivers/gpu/drm/drm_gem_cma_helper.c | 62 ++++++++++++++++++++++++++++++++++++
>>  drivers/gpu/drm/drm_vm.c             |  4 +++
>>  drivers/video/fbdev/core/fbmem.c     | 15 +++++++++
>>  include/drm/drm_gem_cma_helper.h     |  6 ++++
>>  6 files changed, 93 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
>> index 8d9cf73..36c102b 100644
>> --- a/drivers/gpu/drm/Kconfig
>> +++ b/drivers/gpu/drm/Kconfig
>> @@ -6,7 +6,7 @@
>>  #
>>  menuconfig DRM
>>       tristate "Direct Rendering Manager (XFree86 4.1.0 and higher DRI support)"
>> -     depends on (AGP || AGP=n) && !EMULATED_CMPXCHG && MMU && HAS_DMA
>> +     depends on (AGP || AGP=n) && !EMULATED_CMPXCHG && HAS_DMA
>>       select HDMI
>>       select FB_CMDLINE
>>       select I2C
>> @@ -98,7 +98,7 @@ config DRM_LOAD_EDID_FIRMWARE
>>
>>  config DRM_TTM
>>       tristate
>> -     depends on DRM
>> +     depends on DRM && MMU
>>       help
>>         GPU memory management subsystem for devices with multiple
>>         GPU memory types. Will be enabled automatically if a device driver
>> diff --git a/drivers/gpu/drm/drm_fb_cma_helper.c b/drivers/gpu/drm/drm_fb_cma_helper.c
>> index 81b3558..b1414b6 100644
>> --- a/drivers/gpu/drm/drm_fb_cma_helper.c
>> +++ b/drivers/gpu/drm/drm_fb_cma_helper.c
>> @@ -343,8 +343,12 @@ int drm_fb_cma_debugfs_show(struct seq_file *m, void *arg)
>>
>>  static int drm_fb_cma_mmap(struct fb_info *info, struct vm_area_struct *vma)
>>  {
>> +#ifdef CONFIG_MMU
>>       return dma_mmap_writecombine(info->device, vma, info->screen_base,
>>                                    info->fix.smem_start, info->fix.smem_len);
>> +#else
>> +     return vm_iomap_memory(vma, vma->vm_start, info->fix.smem_len);
>> +#endif
>>  }
>>
>>  static struct fb_ops drm_fbdev_cma_ops = {
>> diff --git a/drivers/gpu/drm/drm_gem_cma_helper.c b/drivers/gpu/drm/drm_gem_cma_helper.c
>> index 1d6c335..de13535 100644
>> --- a/drivers/gpu/drm/drm_gem_cma_helper.c
>> +++ b/drivers/gpu/drm/drm_gem_cma_helper.c
>> @@ -318,11 +318,16 @@ static int drm_gem_cma_mmap_obj(struct drm_gem_cma_object *cma_obj,
>>       vma->vm_flags &= ~VM_PFNMAP;
>>       vma->vm_pgoff = 0;
>>
>> +#ifdef CONFIG_MMU
>>       ret = dma_mmap_wc(cma_obj->base.dev->dev, vma, cma_obj->vaddr,
>>                         cma_obj->paddr, vma->vm_end - vma->vm_start);
>>       if (ret)
>>               drm_gem_vm_close(vma);
>>
>> +#else
>> +     ret = vm_iomap_memory(vma, vma->vm_start,
>> +                           (vma->vm_end - vma->vm_start));
>> +#endif
>
> Ok, me asking for a separate helper was probably too much. The #ifdefs
> here are still ugly, but on 2nd thought this just looks like the dma api
> is broken on no-mmu? Shouldn't we instead have a patch somewhere which
> gives us a working dma_mmap_wc on nommu platforms?
>
>>       return ret;
>>  }
>>
>> @@ -358,6 +363,63 @@ int drm_gem_cma_mmap(struct file *filp, struct vm_area_struct *vma)
>>  }
>>  EXPORT_SYMBOL_GPL(drm_gem_cma_mmap);
>>
>> +#ifdef CONFIG_MMU
>> +#define drm_gem_cma_get_unmapped_area NULL
>
> Depending upon how it's used it might be better to stub it out ...
>
>> +#else
>> +unsigned long drm_gem_cma_get_unmapped_area(struct file *filp,
>> +                                         unsigned long addr,
>> +                                         unsigned long len,
>> +                                         unsigned long pgoff,
>> +                                         unsigned long flags)
>
> With no user and no kerneldoc I kinda have no idea what this is even for.
> The name also doesn't help, it says "get_unmapped_area", but very clearly
> you're returning a kernel vaddr cast to a  long (and with ERR_PTR
> semantics on top, but non-standard). Why is this not called get_vaddr?
> -Daniel
>
>> +{
>> +     struct drm_gem_cma_object *cma_obj;
>> +     struct drm_gem_object *obj = NULL;
>> +     struct drm_file *priv = filp->private_data;
>> +     struct drm_device *dev = priv->minor->dev;
>> +     struct drm_vma_offset_node *node;
>> +
>> +     if (drm_device_is_unplugged(dev))
>> +             return -ENODEV;
>> +
>> +     drm_vma_offset_lock_lookup(dev->vma_offset_manager);
>> +     node = drm_vma_offset_exact_lookup_locked(dev->vma_offset_manager,
>> +                                               pgoff,
>> +                                               len >> PAGE_SHIFT);
>> +     if (likely(node)) {
>> +             obj = container_of(node, struct drm_gem_object, vma_node);
>> +             /*
>> +              * When the object is being freed, after it hits 0-refcnt it
>> +              * proceeds to tear down the object. In the process it will
>> +              * attempt to remove the VMA offset and so acquire this
>> +              * mgr->vm_lock.  Therefore if we find an object with a 0-refcnt
>> +              * that matches our range, we know it is in the process of being
>> +              * destroyed and will be freed as soon as we release the lock -
>> +              * so we have to check for the 0-refcnted object and treat it as
>> +              * invalid.
>> +              */
>> +             if (!kref_get_unless_zero(&obj->refcount))
>> +                     obj = NULL;
>> +     }
>> +
>> +     drm_vma_offset_unlock_lookup(dev->vma_offset_manager);
>> +
>> +     if (!obj)
>> +             return -EINVAL;
>> +
>> +     if (!drm_vma_node_is_allowed(node, priv)) {
>> +             drm_gem_object_unreference_unlocked(obj);
>> +             return -EACCES;
>> +     }
>> +
>> +     cma_obj = to_drm_gem_cma_obj(obj);
>> +
>> +     drm_gem_object_unreference_unlocked(obj);
>> +
>> +     return cma_obj->vaddr ? (unsigned long)cma_obj->vaddr : -EINVAL;
>> +}
>> +#endif
>> +EXPORT_SYMBOL_GPL(drm_gem_cma_get_unmapped_area);
>> +
>>  #ifdef CONFIG_DEBUG_FS
>>  /**
>>   * drm_gem_cma_describe - describe a CMA GEM object for debugfs
>> diff --git a/drivers/gpu/drm/drm_vm.c b/drivers/gpu/drm/drm_vm.c
>> index caa4e4c..974e02b 100644
>> --- a/drivers/gpu/drm/drm_vm.c
>> +++ b/drivers/gpu/drm/drm_vm.c
>> @@ -489,6 +489,7 @@ static int drm_mmap_dma(struct file *filp, struct vm_area_struct *vma)
>>  #if defined(__i386__) || defined(__x86_64__)
>>               pgprot_val(vma->vm_page_prot) &= ~_PAGE_RW;
>>  #else
>> +#ifdef CONFIG_MMU
>>               /* Ye gads this is ugly.  With more thought
>>                  we could move this up higher and use
>>                  `protection_map' instead.  */
>> @@ -497,6 +498,7 @@ static int drm_mmap_dma(struct file *filp, struct vm_area_struct *vma)
>>                            (pte_wrprotect
>>                             (__pte(pgprot_val(vma->vm_page_prot)))));
>>  #endif
>> +#endif
>>       }
>>
>>       vma->vm_ops = &drm_vm_dma_ops;
>> @@ -573,6 +575,7 @@ static int drm_mmap_locked(struct file *filp, struct vm_area_struct *vma)
>>  #if defined(__i386__) || defined(__x86_64__)
>>               pgprot_val(vma->vm_page_prot) &= ~_PAGE_RW;
>>  #else
>> +#ifdef CONFIG_MMU
>>               /* Ye gads this is ugly.  With more thought
>>                  we could move this up higher and use
>>                  `protection_map' instead.  */
>> @@ -581,6 +584,7 @@ static int drm_mmap_locked(struct file *filp, struct vm_area_struct *vma)
>>                            (pte_wrprotect
>>                             (__pte(pgprot_val(vma->vm_page_prot)))));
>>  #endif
>> +#endif
>>       }
>>
>>       switch (map->type) {
>> diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c
>> index 76c1ad9..54488ee 100644
>> --- a/drivers/video/fbdev/core/fbmem.c
>> +++ b/drivers/video/fbdev/core/fbmem.c
>> @@ -1492,6 +1492,21 @@ static long fb_compat_ioctl(struct file *file, unsigned int cmd,
>>       return 0;
>>  }
>>
>> +#if defined(HAVE_ARCH_FB_UNMAPPED_AREA) && !defined(get_fb_unmapped_area)
>> +unsigned long get_fb_unmapped_area(struct file *filp,
>> +                                 unsigned long addr, unsigned long len,
>> +                                 unsigned long pgoff, unsigned long flags)
>> +{
>> +     struct fb_info * const info = filp->private_data;
>> +     unsigned long fb_size = PAGE_ALIGN(info->fix.smem_len);
>> +
>> +     if (pgoff > fb_size || len > fb_size - pgoff)
>> +             return -EINVAL;
>> +
>> +     return (unsigned long)info->screen_base + pgoff;
>> +}
>> +#endif
>> +
>>  static const struct file_operations fb_fops = {
>>       .owner =        THIS_MODULE,
>>       .read =         fb_read,
>> diff --git a/include/drm/drm_gem_cma_helper.h b/include/drm/drm_gem_cma_helper.h
>> index acd6af8..177a20d 100644
>> --- a/include/drm/drm_gem_cma_helper.h
>> +++ b/include/drm/drm_gem_cma_helper.h
>> @@ -53,6 +53,12 @@ struct drm_gem_cma_object *drm_gem_cma_create(struct drm_device *drm,
>>
>>  extern const struct vm_operations_struct drm_gem_cma_vm_ops;
>>
>> +unsigned long drm_gem_cma_get_unmapped_area(struct file *filp,
>> +                                          unsigned long addr,
>> +                                          unsigned long len,
>> +                                          unsigned long pgoff,
>> +                                          unsigned long flags);
>> +
>>  #ifdef CONFIG_DEBUG_FS
>>  void drm_gem_cma_describe(struct drm_gem_cma_object *obj, struct seq_file *m);
>>  #endif
>> --
>> 1.9.1
>>
>
> --
> Daniel Vetter
> Software Engineer, Intel Corporation
> http://blog.ffwll.ch
Benjamin Gaignard Dec. 1, 2016, 7:21 a.m. | #4
2016-12-01 7:56 GMT+01:00 Daniel Vetter <daniel@ffwll.ch>:
> On Wed, Nov 30, 2016 at 02:19:18PM +0100, Benjamin Gaignard wrote:
>> Some SoC without MMU have display driver where a drm/kms driver
>> could be implemented.
>> Before doing such kind of thing drm/kms must allow to use mmuless
>> devices.
>> This patch propose to remove MMU configuration flag and add some
>> cma helpers functions to help implementing mmuless display driver
>>
>> version 2:
>> - define get_fb_unmapped_area() in drivers/video/fbdev/core/fbmem.c
>>   if HAVE_ARCH_FB_UNMAPPED_AREA is set and get_fb_unmapped_area not
>>   already defined in the architecture
>>
>> Signed-off-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>
>> ---
>>  drivers/gpu/drm/Kconfig              |  4 +--
>>  drivers/gpu/drm/drm_fb_cma_helper.c  |  4 +++
>>  drivers/gpu/drm/drm_gem_cma_helper.c | 62 ++++++++++++++++++++++++++++++++++++
>>  drivers/gpu/drm/drm_vm.c             |  4 +++
>>  drivers/video/fbdev/core/fbmem.c     | 15 +++++++++
>>  include/drm/drm_gem_cma_helper.h     |  6 ++++
>>  6 files changed, 93 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
>> index 8d9cf73..36c102b 100644
>> --- a/drivers/gpu/drm/Kconfig
>> +++ b/drivers/gpu/drm/Kconfig
>> @@ -6,7 +6,7 @@
>>  #
>>  menuconfig DRM
>>       tristate "Direct Rendering Manager (XFree86 4.1.0 and higher DRI support)"
>> -     depends on (AGP || AGP=n) && !EMULATED_CMPXCHG && MMU && HAS_DMA
>> +     depends on (AGP || AGP=n) && !EMULATED_CMPXCHG && HAS_DMA
>>       select HDMI
>>       select FB_CMDLINE
>>       select I2C
>> @@ -98,7 +98,7 @@ config DRM_LOAD_EDID_FIRMWARE
>>
>>  config DRM_TTM
>>       tristate
>> -     depends on DRM
>> +     depends on DRM && MMU
>>       help
>>         GPU memory management subsystem for devices with multiple
>>         GPU memory types. Will be enabled automatically if a device driver
>> diff --git a/drivers/gpu/drm/drm_fb_cma_helper.c b/drivers/gpu/drm/drm_fb_cma_helper.c
>> index 81b3558..b1414b6 100644
>> --- a/drivers/gpu/drm/drm_fb_cma_helper.c
>> +++ b/drivers/gpu/drm/drm_fb_cma_helper.c
>> @@ -343,8 +343,12 @@ int drm_fb_cma_debugfs_show(struct seq_file *m, void *arg)
>>
>>  static int drm_fb_cma_mmap(struct fb_info *info, struct vm_area_struct *vma)
>>  {
>> +#ifdef CONFIG_MMU
>>       return dma_mmap_writecombine(info->device, vma, info->screen_base,
>>                                    info->fix.smem_start, info->fix.smem_len);
>> +#else
>> +     return vm_iomap_memory(vma, vma->vm_start, info->fix.smem_len);
>> +#endif
>>  }
>>
>>  static struct fb_ops drm_fbdev_cma_ops = {
>> diff --git a/drivers/gpu/drm/drm_gem_cma_helper.c b/drivers/gpu/drm/drm_gem_cma_helper.c
>> index 1d6c335..de13535 100644
>> --- a/drivers/gpu/drm/drm_gem_cma_helper.c
>> +++ b/drivers/gpu/drm/drm_gem_cma_helper.c
>> @@ -318,11 +318,16 @@ static int drm_gem_cma_mmap_obj(struct drm_gem_cma_object *cma_obj,
>>       vma->vm_flags &= ~VM_PFNMAP;
>>       vma->vm_pgoff = 0;
>>
>> +#ifdef CONFIG_MMU
>>       ret = dma_mmap_wc(cma_obj->base.dev->dev, vma, cma_obj->vaddr,
>>                         cma_obj->paddr, vma->vm_end - vma->vm_start);
>>       if (ret)
>>               drm_gem_vm_close(vma);
>>
>> +#else
>> +     ret = vm_iomap_memory(vma, vma->vm_start,
>> +                           (vma->vm_end - vma->vm_start));
>> +#endif
>
> Ok, me asking for a separate helper was probably too much. The #ifdefs
> here are still ugly, but on 2nd thought this just looks like the dma api
> is broken on no-mmu? Shouldn't we instead have a patch somewhere which
> gives us a working dma_mmap_wc on nommu platforms?
>

I not sure that dma_mmap_wc is broken for all nommu platforms, but at least
for ARM nommu it return an error:
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/arch/arm/mm/dma-mapping.c#n851

Could it be an alternative to call vm_iomap_memory if dma_map_wc has
failed and !CONFIG_MMU ?

>>       return ret;
>>  }
>>
>> @@ -358,6 +363,63 @@ int drm_gem_cma_mmap(struct file *filp, struct vm_area_struct *vma)
>>  }
>>  EXPORT_SYMBOL_GPL(drm_gem_cma_mmap);
>>
>> +#ifdef CONFIG_MMU
>> +#define drm_gem_cma_get_unmapped_area NULL
>
> Depending upon how it's used it might be better to stub it out ...

This function shouldn't be called in MMU case but I can remove the
flag and compile it for any case

>
>> +#else
>> +unsigned long drm_gem_cma_get_unmapped_area(struct file *filp,
>> +                                         unsigned long addr,
>> +                                         unsigned long len,
>> +                                         unsigned long pgoff,
>> +                                         unsigned long flags)
>
> With no user and no kerneldoc I kinda have no idea what this is even for.
> The name also doesn't help, it says "get_unmapped_area", but very clearly
> you're returning a kernel vaddr cast to a  long (and with ERR_PTR
> semantics on top, but non-standard). Why is this not called get_vaddr?

This function will be used in driver file_operations structure to set
get_unmapped_area field.
For example v4l2 driver use it:
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/drivers/media/v4l2-core/v4l2-dev.c#n462
I don't have found so much examples of that but each time they have
keep "get_unmapped_area"
in function name so I just do the same.

In Documentation/nommu-mmap.txt you have few words about get_unmapped_area()

> -Daniel
>
>> +{
>> +     struct drm_gem_cma_object *cma_obj;
>> +     struct drm_gem_object *obj = NULL;
>> +     struct drm_file *priv = filp->private_data;
>> +     struct drm_device *dev = priv->minor->dev;
>> +     struct drm_vma_offset_node *node;
>> +
>> +     if (drm_device_is_unplugged(dev))
>> +             return -ENODEV;
>> +
>> +     drm_vma_offset_lock_lookup(dev->vma_offset_manager);
>> +     node = drm_vma_offset_exact_lookup_locked(dev->vma_offset_manager,
>> +                                               pgoff,
>> +                                               len >> PAGE_SHIFT);
>> +     if (likely(node)) {
>> +             obj = container_of(node, struct drm_gem_object, vma_node);
>> +             /*
>> +              * When the object is being freed, after it hits 0-refcnt it
>> +              * proceeds to tear down the object. In the process it will
>> +              * attempt to remove the VMA offset and so acquire this
>> +              * mgr->vm_lock.  Therefore if we find an object with a 0-refcnt
>> +              * that matches our range, we know it is in the process of being
>> +              * destroyed and will be freed as soon as we release the lock -
>> +              * so we have to check for the 0-refcnted object and treat it as
>> +              * invalid.
>> +              */
>> +             if (!kref_get_unless_zero(&obj->refcount))
>> +                     obj = NULL;
>> +     }
>> +
>> +     drm_vma_offset_unlock_lookup(dev->vma_offset_manager);
>> +
>> +     if (!obj)
>> +             return -EINVAL;
>> +
>> +     if (!drm_vma_node_is_allowed(node, priv)) {
>> +             drm_gem_object_unreference_unlocked(obj);
>> +             return -EACCES;
>> +     }
>> +
>> +     cma_obj = to_drm_gem_cma_obj(obj);
>> +
>> +     drm_gem_object_unreference_unlocked(obj);
>> +
>> +     return cma_obj->vaddr ? (unsigned long)cma_obj->vaddr : -EINVAL;
>> +}
>> +#endif
>> +EXPORT_SYMBOL_GPL(drm_gem_cma_get_unmapped_area);
>> +
>>  #ifdef CONFIG_DEBUG_FS
>>  /**
>>   * drm_gem_cma_describe - describe a CMA GEM object for debugfs
>> diff --git a/drivers/gpu/drm/drm_vm.c b/drivers/gpu/drm/drm_vm.c
>> index caa4e4c..974e02b 100644
>> --- a/drivers/gpu/drm/drm_vm.c
>> +++ b/drivers/gpu/drm/drm_vm.c
>> @@ -489,6 +489,7 @@ static int drm_mmap_dma(struct file *filp, struct vm_area_struct *vma)
>>  #if defined(__i386__) || defined(__x86_64__)
>>               pgprot_val(vma->vm_page_prot) &= ~_PAGE_RW;
>>  #else
>> +#ifdef CONFIG_MMU
>>               /* Ye gads this is ugly.  With more thought
>>                  we could move this up higher and use
>>                  `protection_map' instead.  */
>> @@ -497,6 +498,7 @@ static int drm_mmap_dma(struct file *filp, struct vm_area_struct *vma)
>>                            (pte_wrprotect
>>                             (__pte(pgprot_val(vma->vm_page_prot)))));
>>  #endif
>> +#endif
>>       }
>>
>>       vma->vm_ops = &drm_vm_dma_ops;
>> @@ -573,6 +575,7 @@ static int drm_mmap_locked(struct file *filp, struct vm_area_struct *vma)
>>  #if defined(__i386__) || defined(__x86_64__)
>>               pgprot_val(vma->vm_page_prot) &= ~_PAGE_RW;
>>  #else
>> +#ifdef CONFIG_MMU
>>               /* Ye gads this is ugly.  With more thought
>>                  we could move this up higher and use
>>                  `protection_map' instead.  */
>> @@ -581,6 +584,7 @@ static int drm_mmap_locked(struct file *filp, struct vm_area_struct *vma)
>>                            (pte_wrprotect
>>                             (__pte(pgprot_val(vma->vm_page_prot)))));
>>  #endif
>> +#endif
>>       }
>>
>>       switch (map->type) {
>> diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c
>> index 76c1ad9..54488ee 100644
>> --- a/drivers/video/fbdev/core/fbmem.c
>> +++ b/drivers/video/fbdev/core/fbmem.c
>> @@ -1492,6 +1492,21 @@ static long fb_compat_ioctl(struct file *file, unsigned int cmd,
>>       return 0;
>>  }
>>
>> +#if defined(HAVE_ARCH_FB_UNMAPPED_AREA) && !defined(get_fb_unmapped_area)
>> +unsigned long get_fb_unmapped_area(struct file *filp,
>> +                                 unsigned long addr, unsigned long len,
>> +                                 unsigned long pgoff, unsigned long flags)
>> +{
>> +     struct fb_info * const info = filp->private_data;
>> +     unsigned long fb_size = PAGE_ALIGN(info->fix.smem_len);
>> +
>> +     if (pgoff > fb_size || len > fb_size - pgoff)
>> +             return -EINVAL;
>> +
>> +     return (unsigned long)info->screen_base + pgoff;
>> +}
>> +#endif
>> +
>>  static const struct file_operations fb_fops = {
>>       .owner =        THIS_MODULE,
>>       .read =         fb_read,
>> diff --git a/include/drm/drm_gem_cma_helper.h b/include/drm/drm_gem_cma_helper.h
>> index acd6af8..177a20d 100644
>> --- a/include/drm/drm_gem_cma_helper.h
>> +++ b/include/drm/drm_gem_cma_helper.h
>> @@ -53,6 +53,12 @@ struct drm_gem_cma_object *drm_gem_cma_create(struct drm_device *drm,
>>
>>  extern const struct vm_operations_struct drm_gem_cma_vm_ops;
>>
>> +unsigned long drm_gem_cma_get_unmapped_area(struct file *filp,
>> +                                          unsigned long addr,
>> +                                          unsigned long len,
>> +                                          unsigned long pgoff,
>> +                                          unsigned long flags);
>> +
>>  #ifdef CONFIG_DEBUG_FS
>>  void drm_gem_cma_describe(struct drm_gem_cma_object *obj, struct seq_file *m);
>>  #endif
>> --
>> 1.9.1
>>
>
> --
> Daniel Vetter
> Software Engineer, Intel Corporation
> http://blog.ffwll.ch
Daniel Vetter Dec. 1, 2016, 8:21 a.m. | #5
On Thu, Dec 01, 2016 at 08:21:11AM +0100, Benjamin Gaignard wrote:
> 2016-12-01 7:56 GMT+01:00 Daniel Vetter <daniel@ffwll.ch>:
> > On Wed, Nov 30, 2016 at 02:19:18PM +0100, Benjamin Gaignard wrote:
> >> Some SoC without MMU have display driver where a drm/kms driver
> >> could be implemented.
> >> Before doing such kind of thing drm/kms must allow to use mmuless
> >> devices.
> >> This patch propose to remove MMU configuration flag and add some
> >> cma helpers functions to help implementing mmuless display driver
> >>
> >> version 2:
> >> - define get_fb_unmapped_area() in drivers/video/fbdev/core/fbmem.c
> >>   if HAVE_ARCH_FB_UNMAPPED_AREA is set and get_fb_unmapped_area not
> >>   already defined in the architecture
> >>
> >> Signed-off-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>
> >> ---
> >>  drivers/gpu/drm/Kconfig              |  4 +--
> >>  drivers/gpu/drm/drm_fb_cma_helper.c  |  4 +++
> >>  drivers/gpu/drm/drm_gem_cma_helper.c | 62 ++++++++++++++++++++++++++++++++++++
> >>  drivers/gpu/drm/drm_vm.c             |  4 +++
> >>  drivers/video/fbdev/core/fbmem.c     | 15 +++++++++
> >>  include/drm/drm_gem_cma_helper.h     |  6 ++++
> >>  6 files changed, 93 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
> >> index 8d9cf73..36c102b 100644
> >> --- a/drivers/gpu/drm/Kconfig
> >> +++ b/drivers/gpu/drm/Kconfig
> >> @@ -6,7 +6,7 @@
> >>  #
> >>  menuconfig DRM
> >>       tristate "Direct Rendering Manager (XFree86 4.1.0 and higher DRI support)"
> >> -     depends on (AGP || AGP=n) && !EMULATED_CMPXCHG && MMU && HAS_DMA
> >> +     depends on (AGP || AGP=n) && !EMULATED_CMPXCHG && HAS_DMA
> >>       select HDMI
> >>       select FB_CMDLINE
> >>       select I2C
> >> @@ -98,7 +98,7 @@ config DRM_LOAD_EDID_FIRMWARE
> >>
> >>  config DRM_TTM
> >>       tristate
> >> -     depends on DRM
> >> +     depends on DRM && MMU
> >>       help
> >>         GPU memory management subsystem for devices with multiple
> >>         GPU memory types. Will be enabled automatically if a device driver
> >> diff --git a/drivers/gpu/drm/drm_fb_cma_helper.c b/drivers/gpu/drm/drm_fb_cma_helper.c
> >> index 81b3558..b1414b6 100644
> >> --- a/drivers/gpu/drm/drm_fb_cma_helper.c
> >> +++ b/drivers/gpu/drm/drm_fb_cma_helper.c
> >> @@ -343,8 +343,12 @@ int drm_fb_cma_debugfs_show(struct seq_file *m, void *arg)
> >>
> >>  static int drm_fb_cma_mmap(struct fb_info *info, struct vm_area_struct *vma)
> >>  {
> >> +#ifdef CONFIG_MMU
> >>       return dma_mmap_writecombine(info->device, vma, info->screen_base,
> >>                                    info->fix.smem_start, info->fix.smem_len);
> >> +#else
> >> +     return vm_iomap_memory(vma, vma->vm_start, info->fix.smem_len);
> >> +#endif
> >>  }
> >>
> >>  static struct fb_ops drm_fbdev_cma_ops = {
> >> diff --git a/drivers/gpu/drm/drm_gem_cma_helper.c b/drivers/gpu/drm/drm_gem_cma_helper.c
> >> index 1d6c335..de13535 100644
> >> --- a/drivers/gpu/drm/drm_gem_cma_helper.c
> >> +++ b/drivers/gpu/drm/drm_gem_cma_helper.c
> >> @@ -318,11 +318,16 @@ static int drm_gem_cma_mmap_obj(struct drm_gem_cma_object *cma_obj,
> >>       vma->vm_flags &= ~VM_PFNMAP;
> >>       vma->vm_pgoff = 0;
> >>
> >> +#ifdef CONFIG_MMU
> >>       ret = dma_mmap_wc(cma_obj->base.dev->dev, vma, cma_obj->vaddr,
> >>                         cma_obj->paddr, vma->vm_end - vma->vm_start);
> >>       if (ret)
> >>               drm_gem_vm_close(vma);
> >>
> >> +#else
> >> +     ret = vm_iomap_memory(vma, vma->vm_start,
> >> +                           (vma->vm_end - vma->vm_start));
> >> +#endif
> >
> > Ok, me asking for a separate helper was probably too much. The #ifdefs
> > here are still ugly, but on 2nd thought this just looks like the dma api
> > is broken on no-mmu? Shouldn't we instead have a patch somewhere which
> > gives us a working dma_mmap_wc on nommu platforms?
> >
> 
> I not sure that dma_mmap_wc is broken for all nommu platforms, but at least
> for ARM nommu it return an error:
> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/arch/arm/mm/dma-mapping.c#n851
> 
> Could it be an alternative to call vm_iomap_memory if dma_map_wc has
> failed and !CONFIG_MMU ?

Sprinkle #ifdefs all over the place is imo the problem, not what exactly
it looks like. Imo this should be fixed in dma-mapping.c.

And if core maintainers hate that, then we need to define a dma_mmap_wc in
drm headers which works better than the core one ;-) Something like:

#ifdef NOMMU
#define dma_mmap_wc drm_dma_mmap_wc

static inline drm_dma_mmap_wc( .... )
{
	vm_remap_memory( ....);
}
#endif

We should probably create a drm-core.h to collect all these (we have a
metric pile of them in i915 for various things that are too hard to get
merged for no good reason).

> >>       return ret;
> >>  }
> >>
> >> @@ -358,6 +363,63 @@ int drm_gem_cma_mmap(struct file *filp, struct vm_area_struct *vma)
> >>  }
> >>  EXPORT_SYMBOL_GPL(drm_gem_cma_mmap);
> >>
> >> +#ifdef CONFIG_MMU
> >> +#define drm_gem_cma_get_unmapped_area NULL
> >
> > Depending upon how it's used it might be better to stub it out ...
> 
> This function shouldn't be called in MMU case but I can remove the
> flag and compile it for any case
> 
> >
> >> +#else
> >> +unsigned long drm_gem_cma_get_unmapped_area(struct file *filp,
> >> +                                         unsigned long addr,
> >> +                                         unsigned long len,
> >> +                                         unsigned long pgoff,
> >> +                                         unsigned long flags)
> >
> > With no user and no kerneldoc I kinda have no idea what this is even for.
> > The name also doesn't help, it says "get_unmapped_area", but very clearly
> > you're returning a kernel vaddr cast to a  long (and with ERR_PTR
> > semantics on top, but non-standard). Why is this not called get_vaddr?
> 
> This function will be used in driver file_operations structure to set
> get_unmapped_area field.
> For example v4l2 driver use it:
> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/drivers/media/v4l2-core/v4l2-dev.c#n462
> I don't have found so much examples of that but each time they have
> keep "get_unmapped_area"
> in function name so I just do the same.
> 
> In Documentation/nommu-mmap.txt you have few words about get_unmapped_area()

Hm ok. I think it's time to digg out an old idea I've had:

#define DRM_GEM_CMA_FOPS(driver) \
static const struct file_operations driver ## _drm_fops = { \
	.owner		= THIS_MODULE, \
	.open		= drm_open, \
	.release	= drm_release, \
	.unlocked_ioctl	= drm_ioctl, \
	.compat_ioctl	= drm_compat_ioctl, \
	.poll		= drm_poll, \
	.read		= drm_read, \
	.llseek		= no_llseek, \
	.mmap		= drm_gem_cma_mmap, \
}; \

Then you have one nice place to put the NOMMU #ifdeffery. Would be great
to roll this out to drivers.

Still need kerneldoc for this new hook, with a reference to
Documentation/nommu-mmap.txt.

I think with that bit of polish&abstraction it makes sense to keep this
all in cma helpers itself.
-Daniel


> 
> > -Daniel
> >
> >> +{
> >> +     struct drm_gem_cma_object *cma_obj;
> >> +     struct drm_gem_object *obj = NULL;
> >> +     struct drm_file *priv = filp->private_data;
> >> +     struct drm_device *dev = priv->minor->dev;
> >> +     struct drm_vma_offset_node *node;
> >> +
> >> +     if (drm_device_is_unplugged(dev))
> >> +             return -ENODEV;
> >> +
> >> +     drm_vma_offset_lock_lookup(dev->vma_offset_manager);
> >> +     node = drm_vma_offset_exact_lookup_locked(dev->vma_offset_manager,
> >> +                                               pgoff,
> >> +                                               len >> PAGE_SHIFT);
> >> +     if (likely(node)) {
> >> +             obj = container_of(node, struct drm_gem_object, vma_node);
> >> +             /*
> >> +              * When the object is being freed, after it hits 0-refcnt it
> >> +              * proceeds to tear down the object. In the process it will
> >> +              * attempt to remove the VMA offset and so acquire this
> >> +              * mgr->vm_lock.  Therefore if we find an object with a 0-refcnt
> >> +              * that matches our range, we know it is in the process of being
> >> +              * destroyed and will be freed as soon as we release the lock -
> >> +              * so we have to check for the 0-refcnted object and treat it as
> >> +              * invalid.
> >> +              */
> >> +             if (!kref_get_unless_zero(&obj->refcount))
> >> +                     obj = NULL;
> >> +     }
> >> +
> >> +     drm_vma_offset_unlock_lookup(dev->vma_offset_manager);
> >> +
> >> +     if (!obj)
> >> +             return -EINVAL;
> >> +
> >> +     if (!drm_vma_node_is_allowed(node, priv)) {
> >> +             drm_gem_object_unreference_unlocked(obj);
> >> +             return -EACCES;
> >> +     }
> >> +
> >> +     cma_obj = to_drm_gem_cma_obj(obj);
> >> +
> >> +     drm_gem_object_unreference_unlocked(obj);
> >> +
> >> +     return cma_obj->vaddr ? (unsigned long)cma_obj->vaddr : -EINVAL;
> >> +}
> >> +#endif
> >> +EXPORT_SYMBOL_GPL(drm_gem_cma_get_unmapped_area);
> >> +
> >>  #ifdef CONFIG_DEBUG_FS
> >>  /**
> >>   * drm_gem_cma_describe - describe a CMA GEM object for debugfs
> >> diff --git a/drivers/gpu/drm/drm_vm.c b/drivers/gpu/drm/drm_vm.c
> >> index caa4e4c..974e02b 100644
> >> --- a/drivers/gpu/drm/drm_vm.c
> >> +++ b/drivers/gpu/drm/drm_vm.c
> >> @@ -489,6 +489,7 @@ static int drm_mmap_dma(struct file *filp, struct vm_area_struct *vma)
> >>  #if defined(__i386__) || defined(__x86_64__)
> >>               pgprot_val(vma->vm_page_prot) &= ~_PAGE_RW;
> >>  #else
> >> +#ifdef CONFIG_MMU
> >>               /* Ye gads this is ugly.  With more thought
> >>                  we could move this up higher and use
> >>                  `protection_map' instead.  */
> >> @@ -497,6 +498,7 @@ static int drm_mmap_dma(struct file *filp, struct vm_area_struct *vma)
> >>                            (pte_wrprotect
> >>                             (__pte(pgprot_val(vma->vm_page_prot)))));
> >>  #endif
> >> +#endif
> >>       }
> >>
> >>       vma->vm_ops = &drm_vm_dma_ops;
> >> @@ -573,6 +575,7 @@ static int drm_mmap_locked(struct file *filp, struct vm_area_struct *vma)
> >>  #if defined(__i386__) || defined(__x86_64__)
> >>               pgprot_val(vma->vm_page_prot) &= ~_PAGE_RW;
> >>  #else
> >> +#ifdef CONFIG_MMU
> >>               /* Ye gads this is ugly.  With more thought
> >>                  we could move this up higher and use
> >>                  `protection_map' instead.  */
> >> @@ -581,6 +584,7 @@ static int drm_mmap_locked(struct file *filp, struct vm_area_struct *vma)
> >>                            (pte_wrprotect
> >>                             (__pte(pgprot_val(vma->vm_page_prot)))));
> >>  #endif
> >> +#endif
> >>       }
> >>
> >>       switch (map->type) {
> >> diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c
> >> index 76c1ad9..54488ee 100644
> >> --- a/drivers/video/fbdev/core/fbmem.c
> >> +++ b/drivers/video/fbdev/core/fbmem.c
> >> @@ -1492,6 +1492,21 @@ static long fb_compat_ioctl(struct file *file, unsigned int cmd,
> >>       return 0;
> >>  }
> >>
> >> +#if defined(HAVE_ARCH_FB_UNMAPPED_AREA) && !defined(get_fb_unmapped_area)
> >> +unsigned long get_fb_unmapped_area(struct file *filp,
> >> +                                 unsigned long addr, unsigned long len,
> >> +                                 unsigned long pgoff, unsigned long flags)
> >> +{
> >> +     struct fb_info * const info = filp->private_data;
> >> +     unsigned long fb_size = PAGE_ALIGN(info->fix.smem_len);
> >> +
> >> +     if (pgoff > fb_size || len > fb_size - pgoff)
> >> +             return -EINVAL;
> >> +
> >> +     return (unsigned long)info->screen_base + pgoff;
> >> +}
> >> +#endif
> >> +
> >>  static const struct file_operations fb_fops = {
> >>       .owner =        THIS_MODULE,
> >>       .read =         fb_read,
> >> diff --git a/include/drm/drm_gem_cma_helper.h b/include/drm/drm_gem_cma_helper.h
> >> index acd6af8..177a20d 100644
> >> --- a/include/drm/drm_gem_cma_helper.h
> >> +++ b/include/drm/drm_gem_cma_helper.h
> >> @@ -53,6 +53,12 @@ struct drm_gem_cma_object *drm_gem_cma_create(struct drm_device *drm,
> >>
> >>  extern const struct vm_operations_struct drm_gem_cma_vm_ops;
> >>
> >> +unsigned long drm_gem_cma_get_unmapped_area(struct file *filp,
> >> +                                          unsigned long addr,
> >> +                                          unsigned long len,
> >> +                                          unsigned long pgoff,
> >> +                                          unsigned long flags);
> >> +
> >>  #ifdef CONFIG_DEBUG_FS
> >>  void drm_gem_cma_describe(struct drm_gem_cma_object *obj, struct seq_file *m);
> >>  #endif
> >> --
> >> 1.9.1
> >>
> >
> > --
> > Daniel Vetter
> > Software Engineer, Intel Corporation
> > http://blog.ffwll.ch
> 
> 
> 
> -- 
> Benjamin Gaignard
> 
> Graphic Study Group
> 
> Linaro.org │ Open source software for ARM SoCs
> 
> Follow Linaro: Facebook | Twitter | Blog

Patch hide | download patch | download mbox

diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
index 8d9cf73..36c102b 100644
--- a/drivers/gpu/drm/Kconfig
+++ b/drivers/gpu/drm/Kconfig
@@ -6,7 +6,7 @@ 
 #
 menuconfig DRM
 	tristate "Direct Rendering Manager (XFree86 4.1.0 and higher DRI support)"
-	depends on (AGP || AGP=n) && !EMULATED_CMPXCHG && MMU && HAS_DMA
+	depends on (AGP || AGP=n) && !EMULATED_CMPXCHG && HAS_DMA
 	select HDMI
 	select FB_CMDLINE
 	select I2C
@@ -98,7 +98,7 @@  config DRM_LOAD_EDID_FIRMWARE
 
 config DRM_TTM
 	tristate
-	depends on DRM
+	depends on DRM && MMU
 	help
 	  GPU memory management subsystem for devices with multiple
 	  GPU memory types. Will be enabled automatically if a device driver
diff --git a/drivers/gpu/drm/drm_fb_cma_helper.c b/drivers/gpu/drm/drm_fb_cma_helper.c
index 81b3558..b1414b6 100644
--- a/drivers/gpu/drm/drm_fb_cma_helper.c
+++ b/drivers/gpu/drm/drm_fb_cma_helper.c
@@ -343,8 +343,12 @@  int drm_fb_cma_debugfs_show(struct seq_file *m, void *arg)
 
 static int drm_fb_cma_mmap(struct fb_info *info, struct vm_area_struct *vma)
 {
+#ifdef CONFIG_MMU
 	return dma_mmap_writecombine(info->device, vma, info->screen_base,
 				     info->fix.smem_start, info->fix.smem_len);
+#else
+	return vm_iomap_memory(vma, vma->vm_start, info->fix.smem_len);
+#endif
 }
 
 static struct fb_ops drm_fbdev_cma_ops = {
diff --git a/drivers/gpu/drm/drm_gem_cma_helper.c b/drivers/gpu/drm/drm_gem_cma_helper.c
index 1d6c335..de13535 100644
--- a/drivers/gpu/drm/drm_gem_cma_helper.c
+++ b/drivers/gpu/drm/drm_gem_cma_helper.c
@@ -318,11 +318,16 @@  static int drm_gem_cma_mmap_obj(struct drm_gem_cma_object *cma_obj,
 	vma->vm_flags &= ~VM_PFNMAP;
 	vma->vm_pgoff = 0;
 
+#ifdef CONFIG_MMU
 	ret = dma_mmap_wc(cma_obj->base.dev->dev, vma, cma_obj->vaddr,
 			  cma_obj->paddr, vma->vm_end - vma->vm_start);
 	if (ret)
 		drm_gem_vm_close(vma);
 
+#else
+	ret = vm_iomap_memory(vma, vma->vm_start,
+			      (vma->vm_end - vma->vm_start));
+#endif
 	return ret;
 }
 
@@ -358,6 +363,63 @@  int drm_gem_cma_mmap(struct file *filp, struct vm_area_struct *vma)
 }
 EXPORT_SYMBOL_GPL(drm_gem_cma_mmap);
 
+#ifdef CONFIG_MMU
+#define drm_gem_cma_get_unmapped_area NULL
+#else
+unsigned long drm_gem_cma_get_unmapped_area(struct file *filp,
+					    unsigned long addr,
+					    unsigned long len,
+					    unsigned long pgoff,
+					    unsigned long flags)
+{
+	struct drm_gem_cma_object *cma_obj;
+	struct drm_gem_object *obj = NULL;
+	struct drm_file *priv = filp->private_data;
+	struct drm_device *dev = priv->minor->dev;
+	struct drm_vma_offset_node *node;
+
+	if (drm_device_is_unplugged(dev))
+		return -ENODEV;
+
+	drm_vma_offset_lock_lookup(dev->vma_offset_manager);
+	node = drm_vma_offset_exact_lookup_locked(dev->vma_offset_manager,
+						  pgoff,
+						  len >> PAGE_SHIFT);
+	if (likely(node)) {
+		obj = container_of(node, struct drm_gem_object, vma_node);
+		/*
+		 * When the object is being freed, after it hits 0-refcnt it
+		 * proceeds to tear down the object. In the process it will
+		 * attempt to remove the VMA offset and so acquire this
+		 * mgr->vm_lock.  Therefore if we find an object with a 0-refcnt
+		 * that matches our range, we know it is in the process of being
+		 * destroyed and will be freed as soon as we release the lock -
+		 * so we have to check for the 0-refcnted object and treat it as
+		 * invalid.
+		 */
+		if (!kref_get_unless_zero(&obj->refcount))
+			obj = NULL;
+	}
+
+	drm_vma_offset_unlock_lookup(dev->vma_offset_manager);
+
+	if (!obj)
+		return -EINVAL;
+
+	if (!drm_vma_node_is_allowed(node, priv)) {
+		drm_gem_object_unreference_unlocked(obj);
+		return -EACCES;
+	}
+
+	cma_obj = to_drm_gem_cma_obj(obj);
+
+	drm_gem_object_unreference_unlocked(obj);
+
+	return cma_obj->vaddr ? (unsigned long)cma_obj->vaddr : -EINVAL;
+}
+#endif
+EXPORT_SYMBOL_GPL(drm_gem_cma_get_unmapped_area);
+
 #ifdef CONFIG_DEBUG_FS
 /**
  * drm_gem_cma_describe - describe a CMA GEM object for debugfs
diff --git a/drivers/gpu/drm/drm_vm.c b/drivers/gpu/drm/drm_vm.c
index caa4e4c..974e02b 100644
--- a/drivers/gpu/drm/drm_vm.c
+++ b/drivers/gpu/drm/drm_vm.c
@@ -489,6 +489,7 @@  static int drm_mmap_dma(struct file *filp, struct vm_area_struct *vma)
 #if defined(__i386__) || defined(__x86_64__)
 		pgprot_val(vma->vm_page_prot) &= ~_PAGE_RW;
 #else
+#ifdef CONFIG_MMU
 		/* Ye gads this is ugly.  With more thought
 		   we could move this up higher and use
 		   `protection_map' instead.  */
@@ -497,6 +498,7 @@  static int drm_mmap_dma(struct file *filp, struct vm_area_struct *vma)
 			     (pte_wrprotect
 			      (__pte(pgprot_val(vma->vm_page_prot)))));
 #endif
+#endif
 	}
 
 	vma->vm_ops = &drm_vm_dma_ops;
@@ -573,6 +575,7 @@  static int drm_mmap_locked(struct file *filp, struct vm_area_struct *vma)
 #if defined(__i386__) || defined(__x86_64__)
 		pgprot_val(vma->vm_page_prot) &= ~_PAGE_RW;
 #else
+#ifdef CONFIG_MMU
 		/* Ye gads this is ugly.  With more thought
 		   we could move this up higher and use
 		   `protection_map' instead.  */
@@ -581,6 +584,7 @@  static int drm_mmap_locked(struct file *filp, struct vm_area_struct *vma)
 			     (pte_wrprotect
 			      (__pte(pgprot_val(vma->vm_page_prot)))));
 #endif
+#endif
 	}
 
 	switch (map->type) {
diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c
index 76c1ad9..54488ee 100644
--- a/drivers/video/fbdev/core/fbmem.c
+++ b/drivers/video/fbdev/core/fbmem.c
@@ -1492,6 +1492,21 @@  static long fb_compat_ioctl(struct file *file, unsigned int cmd,
 	return 0;
 }
 
+#if defined(HAVE_ARCH_FB_UNMAPPED_AREA) && !defined(get_fb_unmapped_area)
+unsigned long get_fb_unmapped_area(struct file *filp,
+				    unsigned long addr, unsigned long len,
+				    unsigned long pgoff, unsigned long flags)
+{
+	struct fb_info * const info = filp->private_data;
+	unsigned long fb_size = PAGE_ALIGN(info->fix.smem_len);
+
+	if (pgoff > fb_size || len > fb_size - pgoff)
+		return -EINVAL;
+
+	return (unsigned long)info->screen_base + pgoff;
+}
+#endif
+
 static const struct file_operations fb_fops = {
 	.owner =	THIS_MODULE,
 	.read =		fb_read,
diff --git a/include/drm/drm_gem_cma_helper.h b/include/drm/drm_gem_cma_helper.h
index acd6af8..177a20d 100644
--- a/include/drm/drm_gem_cma_helper.h
+++ b/include/drm/drm_gem_cma_helper.h
@@ -53,6 +53,12 @@  struct drm_gem_cma_object *drm_gem_cma_create(struct drm_device *drm,
 
 extern const struct vm_operations_struct drm_gem_cma_vm_ops;
 
+unsigned long drm_gem_cma_get_unmapped_area(struct file *filp,
+					     unsigned long addr,
+					     unsigned long len,
+					     unsigned long pgoff,
+					     unsigned long flags);
+
 #ifdef CONFIG_DEBUG_FS
 void drm_gem_cma_describe(struct drm_gem_cma_object *obj, struct seq_file *m);
 #endif