| Message ID | 20230824092133.39510-2-benjamin.gaignard@collabora.com |
|---|---|
| State | New |
| Headers | show |
| Series | Add DELETE_BUF ioctl | expand |
Le 30/08/2023 à 14:25, Hans Verkuil a écrit : > On 24/08/2023 11:21, Benjamin Gaignard wrote: >> Change how offset 'cookie' field value is computed to make possible >> to use more buffers (up to 0xffff). >> With this encoding pattern we know the maximum number that a queue >> could store so we can check ing at queue init time. >> It also make easier and faster to find buffer and plane from using >> the offset field. >> >> Signed-off-by: Benjamin Gaignard <benjamin.gaignard@collabora.com> >> --- >> v5: >> - I haven't change DST_QUEUE_OFF_BASE definition because it used in >> v4l2-mem2mem and s5p_mfc driver with a shift. >> >> .../media/common/videobuf2/videobuf2-core.c | 48 +++++++++---------- >> 1 file changed, 24 insertions(+), 24 deletions(-) >> >> diff --git a/drivers/media/common/videobuf2/videobuf2-core.c b/drivers/media/common/videobuf2/videobuf2-core.c >> index cf6727d9c81f..e06905533ef4 100644 >> --- a/drivers/media/common/videobuf2/videobuf2-core.c >> +++ b/drivers/media/common/videobuf2/videobuf2-core.c >> @@ -31,6 +31,10 @@ >> >> #include <trace/events/vb2.h> >> >> +#define PLANE_INDEX_SHIFT 3 >> +#define PLANE_INDEX_MASK 0x7 >> +#define MAX_BUFFERS 0xffff > Very poor name, see below. > >> + >> static int debug; >> module_param(debug, int, 0644); >> >> @@ -358,21 +362,23 @@ static void __setup_offsets(struct vb2_buffer *vb) >> unsigned int plane; >> unsigned long off = 0; >> >> - if (vb->index) { >> - struct vb2_buffer *prev = q->bufs[vb->index - 1]; >> - struct vb2_plane *p = &prev->planes[prev->num_planes - 1]; >> - >> - off = PAGE_ALIGN(p->m.offset + p->length); >> - } >> + /* >> + * Offsets cookies value have the following constraints: >> + * - a buffer could have up to 8 planes. >> + * - v4l2 mem2mem use bit 30 to distinguish between source and destination buffers. >> + * - must be page aligned >> + * That led to this bit mapping: >> + * |30 |29 15|14 12|11 0| >> + * |DST_QUEUE_OFF_BASE|buffer index|plane index| 0 | >> + * where there is 16 bits to store buffer index. > 16 -> 15: there are 15 (not 16!) bits available for buffer indices. So the maximum > number of buffers is 32768, given that the indices start at 0. > >> + */ >> + off = vb->index << (PLANE_INDEX_SHIFT + PAGE_SHIFT); >> >> for (plane = 0; plane < vb->num_planes; ++plane) { >> - vb->planes[plane].m.offset = off; >> + vb->planes[plane].m.offset = off + (plane << PAGE_SHIFT); >> >> dprintk(q, 3, "buffer %d, plane %d offset 0x%08lx\n", >> vb->index, plane, off); >> - >> - off += vb->planes[plane].length; >> - off = PAGE_ALIGN(off); >> } >> } >> >> @@ -2209,21 +2215,15 @@ static int __find_plane_by_offset(struct vb2_queue *q, unsigned long off, >> 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 = (off >> (PLANE_INDEX_SHIFT + PAGE_SHIFT)) & MAX_BUFFERS; > Hmm, you use it as a mask. The name MAX_BUFFERS is really confusing. > How about BUFFER_INDEX_MASK? That is consistent with PLANE_INDEX_MASK. I will follow your advice and fix that in next version. I will until you have finish your review in this series before send it. Regards, Benjamin > >> + plane = (off >> PAGE_SHIFT) & PLANE_INDEX_MASK; >> >> - for (plane = 0; plane < vb->num_planes; ++plane) { >> - if (vb->planes[plane].m.offset == off) { >> - *_buffer = buffer; >> - *_plane = plane; >> - return 0; >> - } >> - } >> + vb = q->bufs[buffer]; >> + if (vb->planes[plane].m.offset == off) { >> + *_buffer = buffer; >> + *_plane = plane; >> + return 0; >> } >> >> return -EINVAL; > Regards, > > Hans >
diff --git a/drivers/media/common/videobuf2/videobuf2-core.c b/drivers/media/common/videobuf2/videobuf2-core.c index cf6727d9c81f..e06905533ef4 100644 --- a/drivers/media/common/videobuf2/videobuf2-core.c +++ b/drivers/media/common/videobuf2/videobuf2-core.c @@ -31,6 +31,10 @@ #include <trace/events/vb2.h> +#define PLANE_INDEX_SHIFT 3 +#define PLANE_INDEX_MASK 0x7 +#define MAX_BUFFERS 0xffff + static int debug; module_param(debug, int, 0644); @@ -358,21 +362,23 @@ static void __setup_offsets(struct vb2_buffer *vb) unsigned int plane; unsigned long off = 0; - if (vb->index) { - struct vb2_buffer *prev = q->bufs[vb->index - 1]; - struct vb2_plane *p = &prev->planes[prev->num_planes - 1]; - - off = PAGE_ALIGN(p->m.offset + p->length); - } + /* + * Offsets cookies value have the following constraints: + * - a buffer could have up to 8 planes. + * - v4l2 mem2mem use bit 30 to distinguish between source and destination buffers. + * - must be page aligned + * That led to this bit mapping: + * |30 |29 15|14 12|11 0| + * |DST_QUEUE_OFF_BASE|buffer index|plane index| 0 | + * where there is 16 bits to store buffer index. + */ + off = vb->index << (PLANE_INDEX_SHIFT + PAGE_SHIFT); for (plane = 0; plane < vb->num_planes; ++plane) { - vb->planes[plane].m.offset = off; + vb->planes[plane].m.offset = off + (plane << PAGE_SHIFT); dprintk(q, 3, "buffer %d, plane %d offset 0x%08lx\n", vb->index, plane, off); - - off += vb->planes[plane].length; - off = PAGE_ALIGN(off); } } @@ -2209,21 +2215,15 @@ static int __find_plane_by_offset(struct vb2_queue *q, unsigned long off, 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 = (off >> (PLANE_INDEX_SHIFT + PAGE_SHIFT)) & MAX_BUFFERS; + plane = (off >> PAGE_SHIFT) & PLANE_INDEX_MASK; - for (plane = 0; plane < vb->num_planes; ++plane) { - if (vb->planes[plane].m.offset == off) { - *_buffer = buffer; - *_plane = plane; - return 0; - } - } + vb = q->bufs[buffer]; + if (vb->planes[plane].m.offset == off) { + *_buffer = buffer; + *_plane = plane; + return 0; } return -EINVAL;
Change how offset 'cookie' field value is computed to make possible to use more buffers (up to 0xffff). With this encoding pattern we know the maximum number that a queue could store so we can check ing at queue init time. It also make easier and faster to find buffer and plane from using the offset field. Signed-off-by: Benjamin Gaignard <benjamin.gaignard@collabora.com> --- v5: - I haven't change DST_QUEUE_OFF_BASE definition because it used in v4l2-mem2mem and s5p_mfc driver with a shift. .../media/common/videobuf2/videobuf2-core.c | 48 +++++++++---------- 1 file changed, 24 insertions(+), 24 deletions(-)