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
+
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;
--
2.39.2
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. > + 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
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 >
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