| Message ID | 20231031163104.112469-3-benjamin.gaignard@collabora.com |
|---|---|
| State | Superseded |
| Headers | show |
| Series | Add DELETE_BUF ioctl | expand |
On 08/11/2023 11:14, Benjamin Gaignard wrote: > > Le 08/11/2023 à 07:23, Tomasz Figa a écrit : >> Hi Benjamin, >> >> On Tue, Oct 31, 2023 at 05:30:10PM +0100, Benjamin Gaignard wrote: >>> Change how offset 'cookie' field value is computed to make possible >>> to use more buffers. >>> The maximum number of buffers depends of PAGE_SHIFT value and can >>> go up to 0x7fff when PAGE_SHIFT = 12. >>> With this encoding pattern we know the maximum number that a queue >>> could store so we can check it at queue init time. >>> It also make easier and faster to find buffer and plane from using >>> the offset field. >>> Change __find_plane_by_offset() prototype to return the video buffer >>> itself rather than it index. >>> >>> Signed-off-by: Benjamin Gaignard <benjamin.gaignard@collabora.com> >>> --- >>> .../media/common/videobuf2/videobuf2-core.c | 73 +++++++++---------- >>> 1 file changed, 35 insertions(+), 38 deletions(-) >>> >> Thanks a lot for working on this series. Just one comment inline. >> >>> diff --git a/drivers/media/common/videobuf2/videobuf2-core.c b/drivers/media/common/videobuf2/videobuf2-core.c >>> index a5e57affeb30..09be8e026044 100644 >>> --- a/drivers/media/common/videobuf2/videobuf2-core.c >>> +++ b/drivers/media/common/videobuf2/videobuf2-core.c >>> @@ -31,6 +31,11 @@ >>> #include <trace/events/vb2.h> >>> +#define PLANE_INDEX_SHIFT (PAGE_SHIFT + 3) >>> +#define PLANE_INDEX_MASK 0x7 >> Could we somehow ensure that it indeed matches VIDEO_MAX_PLANES? >> >> One thing that comes to my mind would be >> >> #define PLANE_INDEX_BITS 3 >> #define PLANE_INDEX_SHIFT (PAGE_SHIFT + PLANE_INDEX_BITS) >> #define PLANE_INDEX_MASK BIT_MASK(PLANE_INDEX_BITS) >> >> BUILD_BUG_ON(BIT(PLANE_INDEX_BITS) != VIDEO_MAX_PLANES); >> >> Alternatively we could change the videodev2.h, so that we have >> >> #define VIDEO_MAX_PLANES_BITS 3 >> #define VIDEO_MAX_PLANES (1U < VIDEO_MAX_PLANES_BITS) >> >> and then we can just VIDEO_MAX_PLANES_BITS in our definitions in this file >> and no checks would be necessary. > > I would prefer this solution. > Hans should I do that in an other patch ? I prefer to not make changes in videodev2.h, to be honest. I think it is fine to just add a check in videobuf2-core.c. Regards, Hans > > Regards, > Benjamin > >> >> Best regards, >> Tomasz >> >>> +#define MAX_BUFFER_INDEX BIT_MASK(30 - PLANE_INDEX_SHIFT) >>> +#define BUFFER_INDEX_MASK (MAX_BUFFER_INDEX - 1) >>> + >>> static int debug; >>> module_param(debug, int, 0644); >>> @@ -358,21 +363,27 @@ static void __setup_offsets(struct vb2_buffer *vb) >>> unsigned int plane; >>> unsigned long offset = 0; >>> - if (vb->index) { >>> - struct vb2_buffer *prev = q->bufs[vb->index - 1]; >>> - struct vb2_plane *p = &prev->planes[prev->num_planes - 1]; >>> - >>> - offset = PAGE_ALIGN(p->m.offset + p->length); >>> - } >>> + /* >>> + * The offset "cookie" value has the following constraints: >>> + * - a buffer can have up to 8 planes. >>> + * - v4l2 mem2mem uses bit 30 to distinguish between >>> + * OUTPUT (aka "source", bit 30 is 0) and >>> + * CAPTURE (aka "destination", bit 30 is 1) buffers. >>> + * - must be page aligned >>> + * That led to this bit mapping when PAGE_SHIFT = 12: >>> + * |30 |29 15|14 12|11 0| >>> + * |DST_QUEUE_OFF_BASE|buffer index|plane index| 0 | >>> + * where there are 15 bits to store the buffer index. >>> + * Depending on PAGE_SHIFT value we can have fewer bits >>> + * to store the buffer index. >>> + */ >>> + offset = vb->index << PLANE_INDEX_SHIFT; >>> for (plane = 0; plane < vb->num_planes; ++plane) { >>> - vb->planes[plane].m.offset = offset; >>> + vb->planes[plane].m.offset = offset + (plane << PAGE_SHIFT); >>> dprintk(q, 3, "buffer %d, plane %d offset 0x%08lx\n", >>> vb->index, plane, offset); >>> - >>> - offset += vb->planes[plane].length; >>> - offset = PAGE_ALIGN(offset); >>> } >>> } >>> @@ -2188,10 +2199,9 @@ EXPORT_SYMBOL_GPL(vb2_core_streamoff); >>> * __find_plane_by_offset() - find plane associated with the given offset >>> */ >>> static int __find_plane_by_offset(struct vb2_queue *q, unsigned long offset, >>> - unsigned int *_buffer, unsigned int *_plane) >>> + struct vb2_buffer **vb, unsigned int *plane) >>> { >>> - struct vb2_buffer *vb; >>> - unsigned int buffer, plane; >>> + unsigned int buffer; >>> /* >>> * Sanity checks to ensure the lock is held, MEMORY_MMAP is >>> @@ -2209,24 +2219,15 @@ static int __find_plane_by_offset(struct vb2_queue *q, unsigned long offset, >>> return -EBUSY; >>> } >>> - /* >>> - * Go over all buffers and their planes, comparing the given offset >>> - * with an offset assigned to each plane. If a match is found, >>> - * return its buffer and plane numbers. >>> - */ >>> - for (buffer = 0; buffer < q->num_buffers; ++buffer) { >>> - vb = q->bufs[buffer]; >>> + /* Get buffer and plane from the offset */ >>> + buffer = (offset >> PLANE_INDEX_SHIFT) & BUFFER_INDEX_MASK; >>> + *plane = (offset >> PAGE_SHIFT) & PLANE_INDEX_MASK; >>> - for (plane = 0; plane < vb->num_planes; ++plane) { >>> - if (vb->planes[plane].m.offset == offset) { >>> - *_buffer = buffer; >>> - *_plane = plane; >>> - return 0; >>> - } >>> - } >>> - } >>> + if (buffer >= q->num_buffers || *plane >= q->bufs[buffer]->num_planes) >>> + return -EINVAL; >>> - return -EINVAL; >>> + *vb = q->bufs[buffer]; >>> + return 0; >>> } >>> int vb2_core_expbuf(struct vb2_queue *q, int *fd, unsigned int type, >>> @@ -2306,7 +2307,7 @@ int vb2_mmap(struct vb2_queue *q, struct vm_area_struct *vma) >>> { >>> unsigned long offset = vma->vm_pgoff << PAGE_SHIFT; >>> struct vb2_buffer *vb; >>> - unsigned int buffer = 0, plane = 0; >>> + unsigned int plane = 0; >>> int ret; >>> unsigned long length; >>> @@ -2335,12 +2336,10 @@ int vb2_mmap(struct vb2_queue *q, struct vm_area_struct *vma) >>> * Find the plane corresponding to the offset passed by userspace. This >>> * will return an error if not MEMORY_MMAP or file I/O is in progress. >>> */ >>> - ret = __find_plane_by_offset(q, offset, &buffer, &plane); >>> + ret = __find_plane_by_offset(q, offset, &vb, &plane); >>> if (ret) >>> goto unlock; >>> - vb = q->bufs[buffer]; >>> - >>> /* >>> * MMAP requires page_aligned buffers. >>> * The buffer length was page_aligned at __vb2_buf_mem_alloc(), >>> @@ -2368,7 +2367,7 @@ int vb2_mmap(struct vb2_queue *q, struct vm_area_struct *vma) >>> if (ret) >>> return ret; >>> - dprintk(q, 3, "buffer %d, plane %d successfully mapped\n", buffer, plane); >>> + dprintk(q, 3, "buffer %u, plane %d successfully mapped\n", vb->index, plane); >>> return 0; >>> } >>> EXPORT_SYMBOL_GPL(vb2_mmap); >>> @@ -2382,7 +2381,7 @@ unsigned long vb2_get_unmapped_area(struct vb2_queue *q, >>> { >>> unsigned long offset = pgoff << PAGE_SHIFT; >>> struct vb2_buffer *vb; >>> - unsigned int buffer, plane; >>> + unsigned int plane; >>> void *vaddr; >>> int ret; >>> @@ -2392,12 +2391,10 @@ unsigned long vb2_get_unmapped_area(struct vb2_queue *q, >>> * Find the plane corresponding to the offset passed by userspace. This >>> * will return an error if not MEMORY_MMAP or file I/O is in progress. >>> */ >>> - ret = __find_plane_by_offset(q, offset, &buffer, &plane); >>> + ret = __find_plane_by_offset(q, offset, &vb, &plane); >>> if (ret) >>> goto unlock; >>> - vb = q->bufs[buffer]; >>> - >>> vaddr = vb2_plane_vaddr(vb, plane); >>> mutex_unlock(&q->mmap_lock); >>> return vaddr ? (unsigned long)vaddr : -EINVAL; >>> -- >>> 2.39.2 >>>
diff --git a/drivers/media/common/videobuf2/videobuf2-core.c b/drivers/media/common/videobuf2/videobuf2-core.c index a5e57affeb30..09be8e026044 100644 --- a/drivers/media/common/videobuf2/videobuf2-core.c +++ b/drivers/media/common/videobuf2/videobuf2-core.c @@ -31,6 +31,11 @@ #include <trace/events/vb2.h> +#define PLANE_INDEX_SHIFT (PAGE_SHIFT + 3) +#define PLANE_INDEX_MASK 0x7 +#define MAX_BUFFER_INDEX BIT_MASK(30 - PLANE_INDEX_SHIFT) +#define BUFFER_INDEX_MASK (MAX_BUFFER_INDEX - 1) + static int debug; module_param(debug, int, 0644); @@ -358,21 +363,27 @@ static void __setup_offsets(struct vb2_buffer *vb) unsigned int plane; unsigned long offset = 0; - if (vb->index) { - struct vb2_buffer *prev = q->bufs[vb->index - 1]; - struct vb2_plane *p = &prev->planes[prev->num_planes - 1]; - - offset = PAGE_ALIGN(p->m.offset + p->length); - } + /* + * The offset "cookie" value has the following constraints: + * - a buffer can have up to 8 planes. + * - v4l2 mem2mem uses bit 30 to distinguish between + * OUTPUT (aka "source", bit 30 is 0) and + * CAPTURE (aka "destination", bit 30 is 1) buffers. + * - must be page aligned + * That led to this bit mapping when PAGE_SHIFT = 12: + * |30 |29 15|14 12|11 0| + * |DST_QUEUE_OFF_BASE|buffer index|plane index| 0 | + * where there are 15 bits to store the buffer index. + * Depending on PAGE_SHIFT value we can have fewer bits + * to store the buffer index. + */ + offset = vb->index << PLANE_INDEX_SHIFT; for (plane = 0; plane < vb->num_planes; ++plane) { - vb->planes[plane].m.offset = offset; + vb->planes[plane].m.offset = offset + (plane << PAGE_SHIFT); dprintk(q, 3, "buffer %d, plane %d offset 0x%08lx\n", vb->index, plane, offset); - - offset += vb->planes[plane].length; - offset = PAGE_ALIGN(offset); } } @@ -2188,10 +2199,9 @@ EXPORT_SYMBOL_GPL(vb2_core_streamoff); * __find_plane_by_offset() - find plane associated with the given offset */ static int __find_plane_by_offset(struct vb2_queue *q, unsigned long offset, - unsigned int *_buffer, unsigned int *_plane) + struct vb2_buffer **vb, unsigned int *plane) { - struct vb2_buffer *vb; - unsigned int buffer, plane; + unsigned int buffer; /* * Sanity checks to ensure the lock is held, MEMORY_MMAP is @@ -2209,24 +2219,15 @@ static int __find_plane_by_offset(struct vb2_queue *q, unsigned long offset, return -EBUSY; } - /* - * Go over all buffers and their planes, comparing the given offset - * with an offset assigned to each plane. If a match is found, - * return its buffer and plane numbers. - */ - for (buffer = 0; buffer < q->num_buffers; ++buffer) { - vb = q->bufs[buffer]; + /* Get buffer and plane from the offset */ + buffer = (offset >> PLANE_INDEX_SHIFT) & BUFFER_INDEX_MASK; + *plane = (offset >> PAGE_SHIFT) & PLANE_INDEX_MASK; - for (plane = 0; plane < vb->num_planes; ++plane) { - if (vb->planes[plane].m.offset == offset) { - *_buffer = buffer; - *_plane = plane; - return 0; - } - } - } + if (buffer >= q->num_buffers || *plane >= q->bufs[buffer]->num_planes) + return -EINVAL; - return -EINVAL; + *vb = q->bufs[buffer]; + return 0; } int vb2_core_expbuf(struct vb2_queue *q, int *fd, unsigned int type, @@ -2306,7 +2307,7 @@ int vb2_mmap(struct vb2_queue *q, struct vm_area_struct *vma) { unsigned long offset = vma->vm_pgoff << PAGE_SHIFT; struct vb2_buffer *vb; - unsigned int buffer = 0, plane = 0; + unsigned int plane = 0; int ret; unsigned long length; @@ -2335,12 +2336,10 @@ int vb2_mmap(struct vb2_queue *q, struct vm_area_struct *vma) * Find the plane corresponding to the offset passed by userspace. This * will return an error if not MEMORY_MMAP or file I/O is in progress. */ - ret = __find_plane_by_offset(q, offset, &buffer, &plane); + ret = __find_plane_by_offset(q, offset, &vb, &plane); if (ret) goto unlock; - vb = q->bufs[buffer]; - /* * MMAP requires page_aligned buffers. * The buffer length was page_aligned at __vb2_buf_mem_alloc(), @@ -2368,7 +2367,7 @@ int vb2_mmap(struct vb2_queue *q, struct vm_area_struct *vma) if (ret) return ret; - dprintk(q, 3, "buffer %d, plane %d successfully mapped\n", buffer, plane); + dprintk(q, 3, "buffer %u, plane %d successfully mapped\n", vb->index, plane); return 0; } EXPORT_SYMBOL_GPL(vb2_mmap); @@ -2382,7 +2381,7 @@ unsigned long vb2_get_unmapped_area(struct vb2_queue *q, { unsigned long offset = pgoff << PAGE_SHIFT; struct vb2_buffer *vb; - unsigned int buffer, plane; + unsigned int plane; void *vaddr; int ret; @@ -2392,12 +2391,10 @@ unsigned long vb2_get_unmapped_area(struct vb2_queue *q, * Find the plane corresponding to the offset passed by userspace. This * will return an error if not MEMORY_MMAP or file I/O is in progress. */ - ret = __find_plane_by_offset(q, offset, &buffer, &plane); + ret = __find_plane_by_offset(q, offset, &vb, &plane); if (ret) goto unlock; - vb = q->bufs[buffer]; - vaddr = vb2_plane_vaddr(vb, plane); mutex_unlock(&q->mmap_lock); return vaddr ? (unsigned long)vaddr : -EINVAL;
Change how offset 'cookie' field value is computed to make possible to use more buffers. The maximum number of buffers depends of PAGE_SHIFT value and can go up to 0x7fff when PAGE_SHIFT = 12. With this encoding pattern we know the maximum number that a queue could store so we can check it at queue init time. It also make easier and faster to find buffer and plane from using the offset field. Change __find_plane_by_offset() prototype to return the video buffer itself rather than it index. Signed-off-by: Benjamin Gaignard <benjamin.gaignard@collabora.com> --- .../media/common/videobuf2/videobuf2-core.c | 73 +++++++++---------- 1 file changed, 35 insertions(+), 38 deletions(-)