[PATCHv1] drm/omap: get fbdev working for manually updated display

Message ID 20210501200050.410704-1-sebastian.reichel@collabora.com
State New
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Series
  • [PATCHv1] drm/omap: get fbdev working for manually updated display
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Commit Message

Sebastian Reichel May 1, 2021, 8 p.m.
Running a legacy application, which directly uses /dev/fb0
currently results in display not being refreshed when the
application mmaps the memory instead of calling write().

Deferred IO support will also schedule dirty_work with the
damage collected from the mmap page writes and thus gets
some more legacy applications working.

Delay frequency settings have been taken over from
drm_fb_helper_generic_probe().

Reported-by: Carl Philipp Klemm <philipp@uvos.xyz>
Tested-by: Carl Philipp Klemm <philipp@uvos.xyz>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>
---
Hi,

I still need to fix my Droid 4, so I only compile tested this
myself.

-- Sebastian
---
 drivers/gpu/drm/omapdrm/omap_fbdev.c | 8 ++++++++
 1 file changed, 8 insertions(+)


base-commit: 152d32aa846835987966fd20ee1143b0e05036a0

Comments

Tomi Valkeinen May 3, 2021, 8:59 a.m. | #1
On 01/05/2021 23:00, Sebastian Reichel wrote:
> Running a legacy application, which directly uses /dev/fb0

> currently results in display not being refreshed when the

> application mmaps the memory instead of calling write().

> 

> Deferred IO support will also schedule dirty_work with the

> damage collected from the mmap page writes and thus gets

> some more legacy applications working.

> 

> Delay frequency settings have been taken over from

> drm_fb_helper_generic_probe().

> 

> Reported-by: Carl Philipp Klemm <philipp@uvos.xyz>

> Tested-by: Carl Philipp Klemm <philipp@uvos.xyz>

> Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>

> ---

> Hi,

> 

> I still need to fix my Droid 4, so I only compile tested this

> myself.

> 

> -- Sebastian

> ---

>   drivers/gpu/drm/omapdrm/omap_fbdev.c | 8 ++++++++

>   1 file changed, 8 insertions(+)

> 

> diff --git a/drivers/gpu/drm/omapdrm/omap_fbdev.c b/drivers/gpu/drm/omapdrm/omap_fbdev.c

> index 42eac6ad12bd..fc3897d2d7cc 100644

> --- a/drivers/gpu/drm/omapdrm/omap_fbdev.c

> +++ b/drivers/gpu/drm/omapdrm/omap_fbdev.c

> @@ -87,6 +87,11 @@ static const struct fb_ops omap_fb_ops = {

>   	.fb_imageblit = drm_fb_helper_sys_imageblit,

>   };

>   

> +static struct fb_deferred_io omap_fb_defio = {

> +	.delay		= HZ / 20,

> +	.deferred_io	= drm_fb_helper_deferred_io,

> +};

> +

>   static int omap_fbdev_create(struct drm_fb_helper *helper,

>   		struct drm_fb_helper_surface_size *sizes)

>   {

> @@ -176,6 +181,9 @@ static int omap_fbdev_create(struct drm_fb_helper *helper,

>   

>   	drm_fb_helper_fill_info(fbi, helper, sizes);

>   

> +	fbi->fbdefio = &omap_fb_defio;

> +	fb_deferred_io_init(fbi);

> +

>   	dev->mode_config.fb_base = dma_addr;

>   

>   	fbi->screen_buffer = omap_gem_vaddr(fbdev->bo);

> 

> base-commit: 152d32aa846835987966fd20ee1143b0e05036a0

> 


On DRA76 EVM, with parallel output, this causes cache-flush problem. 
When I run my simple fbtest, which just draws to the fb, I see lots of 
cache-line artifacts.

When I run kmstest (from kms++), I get a flood of list corruptions 
somewhere in omap_gem. Is it related to "Deferred I/O is not compatible 
with SHMEM"?

  Tomi

Patch

diff --git a/drivers/gpu/drm/omapdrm/omap_fbdev.c b/drivers/gpu/drm/omapdrm/omap_fbdev.c
index 42eac6ad12bd..fc3897d2d7cc 100644
--- a/drivers/gpu/drm/omapdrm/omap_fbdev.c
+++ b/drivers/gpu/drm/omapdrm/omap_fbdev.c
@@ -87,6 +87,11 @@  static const struct fb_ops omap_fb_ops = {
 	.fb_imageblit = drm_fb_helper_sys_imageblit,
 };
 
+static struct fb_deferred_io omap_fb_defio = {
+	.delay		= HZ / 20,
+	.deferred_io	= drm_fb_helper_deferred_io,
+};
+
 static int omap_fbdev_create(struct drm_fb_helper *helper,
 		struct drm_fb_helper_surface_size *sizes)
 {
@@ -176,6 +181,9 @@  static int omap_fbdev_create(struct drm_fb_helper *helper,
 
 	drm_fb_helper_fill_info(fbi, helper, sizes);
 
+	fbi->fbdefio = &omap_fb_defio;
+	fb_deferred_io_init(fbi);
+
 	dev->mode_config.fb_base = dma_addr;
 
 	fbi->screen_buffer = omap_gem_vaddr(fbdev->bo);