| Message ID | 20230914133323.198857-2-benjamin.gaignard@collabora.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | Add DELETE_BUF ioctl | expand |
On 14/09/2023 15:32, Benjamin Gaignard wrote: > Change how offset 'cookie' field value is computed to make possible > to use more buffers (up to 0x7fff) > 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> > --- > .../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..cf3b9f5b69b7 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 (PAGE_SHIFT + 3) > +#define PLANE_INDEX_MASK 0x7 > +#define BUFFER_INDEX_MASK 0x7fff It's a bit paranoid, but I would like to add a check for PAGE_SHIFT here: #if PAGE_SHIFT != 12 #error Expected PAGE_SHIFT to be 12 #endif Things will go very wrong if this value ever changes... > + > 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 15 bits to store buffer index. typo: is -> are > + */ > + off = vb->index << (PLANE_INDEX_SHIFT); No need for (). > > 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) & BUFFER_INDEX_MASK; > + 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]; Hmm, shouldn't there be a sanity check for the buffer value? > + if (vb->planes[plane].m.offset == off) { Does this check make sense? > + *_buffer = buffer; > + *_plane = plane; > + return 0; > } > > return -EINVAL; How about this: /* Get buffer and plane from the offset */ *buffer = (off >> PLANE_INDEX_SHIFT) & BUFFER_INDEX_MASK; *plane = (off >> PAGE_SHIFT) & PLANE_INDEX_MASK; if (*buffer >= q->num_buffers || *plane >= q->bufs[buffer]->num_planes) return -EINVAL; return 0; Regards, Hans
diff --git a/drivers/media/common/videobuf2/videobuf2-core.c b/drivers/media/common/videobuf2/videobuf2-core.c index cf6727d9c81f..cf3b9f5b69b7 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 (PAGE_SHIFT + 3) +#define PLANE_INDEX_MASK 0x7 +#define BUFFER_INDEX_MASK 0x7fff + 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 15 bits to store buffer index. + */ + off = vb->index << (PLANE_INDEX_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) & BUFFER_INDEX_MASK; + 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 0x7fff) 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> --- .../media/common/videobuf2/videobuf2-core.c | 48 +++++++++---------- 1 file changed, 24 insertions(+), 24 deletions(-)