2014-12-19 17:03 GMT+01:00 Kamil Debski <k.deb...@samsung.com>:
> Hi Jean,
>
>> From: Jean-Michel Hautbois [mailto:jhautb...@gmail.com]
>> Sent: Friday, December 19, 2014 3:36 PM
>> To: Kamil Debski
>> Cc: Linux Media Mailing List; m.szyprow...@samsung.com; Hans Verkuil;
>> Nicolas Dufresne
>> Subject: Re: [PATCH 1/2] vb2: Add VB2_FILEIO_ALLOW_ZERO_BYTESUSED flag
>> to vb2_fileio_flags
>>
>> Hi Kamil,
>>
>> 2014-12-16 12:36 GMT+01:00 Kamil Debski <k.deb...@samsung.com>:
>> > The vb2: fix bytesused == 0 handling (8a75ffb) patch changed the
>> > behavior of __fill_vb2_buffer function, so that if bytesused is 0 it
>> > is set to the size of the buffer. However, bytesused set to 0 is used
>> > by older codec drivers as as indication used to mark the end of
>> stream.
>> >
>> > To keep backward compatibility, this patch adds a flag passed to the
>> > vb2_queue_init function - VB2_FILEIO_ALLOW_ZERO_BYTESUSED. If the
>> flag
>> > is set upon initialization of the queue, the videobuf2 keeps the
>> value
>> > of bytesused intact and passes it to the driver.
>>
>> Nice, this is something we were planning to do :).
>> But I would split this patch and the second which is specific to s5p-
>> mfc as this is core specific and should be independant.
>
> This patch contains only changes in the videobuf2-core.c file. The next
> patch in the series contains changes in the s5p-mfc driver. There is
> another patch sent today that adds this flag to coda.
>
> These are all separate patches, two of them are in a single patchset.
> Actually, I would send all of them in one patchset, but initially I missed
> that the coda driver should also have this change applied. (Nicolas, thank
> you for reminding me to do this on IRC).
OK, This is why I have been confused. Well, I still think that core
modification should be a separate patch, and maybe s5f-mpc and coda be
in the same patchset. Not a problem.
>>
>>
>> > Reported-by: Nicolas Dufresne <nicolas.dufre...@collabora.com>
>> > Signed-off-by: Kamil Debski <k.deb...@samsung.com>
>> > ---
>> > drivers/media/v4l2-core/videobuf2-core.c | 33
>> ++++++++++++++++++++++++------
>> > include/media/videobuf2-core.h | 3 +++
>> > 2 files changed, 30 insertions(+), 6 deletions(-)
>> >
>> > diff --git a/drivers/media/v4l2-core/videobuf2-core.c
>> > b/drivers/media/v4l2-core/videobuf2-core.c
>> > index d09a891..1068dbb 100644
>> > --- a/drivers/media/v4l2-core/videobuf2-core.c
>> > +++ b/drivers/media/v4l2-core/videobuf2-core.c
>> > @@ -1276,13 +1276,23 @@ static void __fill_vb2_buffer(struct
>> vb2_buffer *vb, const struct v4l2_buffer *b
>> > * userspace clearly never bothered to set it
>> and
>> > * it's a safe assumption that they really
>> meant to
>> > * use the full plane sizes.
>> > + *
>> > + * Some drivers, e.g. old codec drivers, use
>> bytesused
>> > + * == 0 as a way to indicate that streaming
>> is finished.
>> > + * In that case, the driver should use the
>> following
>> > + * io_flag VB2_FILEIO_ALLOW_ZERO_BYTESUSED to
>> keep old
>> > + * userspace applications working.
>>
>> Not sure if this comment is necessary, as this is already in the
>> commit ?
>
> The comment were present in the file already, I expanded them to cover the
> exception when the VB2_FILEIO_ALLOW_ZERO_BYTESUSED flag is set.
> It is also explained in the commit, I agree, but in the end one usually
> looks in the source code.
OK
>>
>> > */
>> > for (plane = 0; plane < vb->num_planes;
>> ++plane) {
>> > struct v4l2_plane *pdst =
>> &v4l2_planes[plane];
>> > struct v4l2_plane *psrc =
>> > &b->m.planes[plane];
>> >
>> > - pdst->bytesused = psrc->bytesused ?
>> > - psrc->bytesused : pdst-
>> >length;
>> > + if (vb->vb2_queue->io_flags &
>> > +
>> VB2_FILEIO_ALLOW_ZERO_BYTESUSED)
>> > + pdst->bytesused = psrc-
>> >bytesused;
>> > + else
>> > + pdst->bytesused = psrc-
>> >bytesused ?
>> > + psrc->bytesused :
>> > + pdst->length;
>> > pdst->data_offset = psrc->data_offset;
>> > }
>> > }
>> > @@ -1295,6 +1305,12 @@ static void __fill_vb2_buffer(struct
>> vb2_buffer *vb, const struct v4l2_buffer *b
>> > *
>> > * If bytesused == 0 for the output buffer, then fall
>> back
>> > * to the full buffer size as that's a sensible
>> default.
>> > + *
>> > + * Some drivers, e.g. old codec drivers, use
>> bytesused == 0
>> > + * as a way to indicate that streaming is finished.
>> In that
>> > + * case, the driver should use the following io_flag
>> > + * VB2_FILEIO_ALLOW_ZERO_BYTESUSED to keep old
>> userspace
>> > + * applications working.
>>
>> Again, not sure this is useful.
>
> Same applies here, I expanded the comment to cover a new case.
>
>>
>> > */
>> > if (b->memory == V4L2_MEMORY_USERPTR) {
>> > v4l2_planes[0].m.userptr = b->m.userptr; @@
>> > -1306,11 +1322,16 @@ static void __fill_vb2_buffer(struct vb2_buffer
>> *vb, const struct v4l2_buffer *b
>> > v4l2_planes[0].length = b->length;
>> > }
>> >
>> > - if (V4L2_TYPE_IS_OUTPUT(b->type))
>> > - v4l2_planes[0].bytesused = b->bytesused ?
>> > - b->bytesused : v4l2_planes[0].length;
>> > - else
>> > + if (V4L2_TYPE_IS_OUTPUT(b->type)) {
>> > + if (vb->vb2_queue->io_flags &
>> > + VB2_FILEIO_ALLOW_ZERO_BYTESUSED)
>> > + v4l2_planes[0].bytesused = b-
>> >bytesused;
>> > + else
>> > + v4l2_planes[0].bytesused = b-
>> >bytesused ?
>> > + b->bytesused :
>> v4l2_planes[0].length;
>> > + } else {
>> > v4l2_planes[0].bytesused = 0;
>> > + }
>> >
>> > }
>> >
>> > diff --git a/include/media/videobuf2-core.h
>> > b/include/media/videobuf2-core.h index bd2cec2..0540bc3 100644
>> > --- a/include/media/videobuf2-core.h
>> > +++ b/include/media/videobuf2-core.h
>> > @@ -138,10 +138,13 @@ enum vb2_io_modes {
>> > * by default the 'streaming' style is used by the file io emulator
>> > * @VB2_FILEIO_READ_ONCE: report EOF after reading the first
>> buffer
>> > * @VB2_FILEIO_WRITE_IMMEDIATELY: queue buffer after each
>> write() call
>> > + * @VB2_FILEIO_ALLOW_ZERO_BYTESUSED: the driver setting this flag
>> will handle
>> > + * bytesused == 0 as a special
>> case
>> > */
>> > enum vb2_fileio_flags {
>> > VB2_FILEIO_READ_ONCE = (1 << 0),
>> > VB2_FILEIO_WRITE_IMMEDIATELY = (1 << 1),
>> > + VB2_FILEIO_ALLOW_ZERO_BYTESUSED = (1 << 2),
>> > };
>> >
>> > /**
>> > --
>> > 1.7.9.5
>> >
>> > --
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>> > info at http://vger.kernel.org/majordomo-info.html
>>
>> I tested it with your coda patch too on i.MX6, thank you, this was
>> annoying :).
>> JM
>
> You're welcome. Thanks for testing :)
>
> Best wishes,
Thanks, and best wishes too.
JM
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