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media: videobuf2: Rework offset 'cookie' encoding pattern

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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>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>
This commit is contained in:
Benjamin Gaignard 2023-11-09 17:29:14 +01:00 committed by Mauro Carvalho Chehab
parent 07cb30216d
commit 3431e32cb5
1 changed files with 40 additions and 38 deletions
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78
drivers/media/common/videobuf2/videobuf2-core.c
View File

@ -31,6 +31,16 @@
#include <trace/events/vb2.h>
#define PLANE_INDEX_BITS 3
#define PLANE_INDEX_SHIFT (PAGE_SHIFT + PLANE_INDEX_BITS)
#define PLANE_INDEX_MASK (BIT_MASK(PLANE_INDEX_BITS) - 1)
#define MAX_BUFFER_INDEX BIT_MASK(30 - PLANE_INDEX_SHIFT)
#define BUFFER_INDEX_MASK (MAX_BUFFER_INDEX - 1)
#if BIT(PLANE_INDEX_BITS) != VIDEO_MAX_PLANES
#error PLANE_INDEX_BITS order must be equal to VIDEO_MAX_PLANES
#endif
static int debug;
module_param(debug, int, 0644);
@ -358,21 +368,27 @@ 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 +2204,9 @@ 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 +2224,15 @@ 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 +2312,7 @@ 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 +2341,10 @@ 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 +2372,7 @@ unlock:
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 +2386,7 @@ 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 +2396,10 @@ 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;