| Message ID | 20171115171057.17340-2-gustavo@padovan.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Em Wed, 15 Nov 2017 15:10:47 -0200 Gustavo Padovan <gustavo@padovan.org> escreveu: > From: Gustavo Padovan <gustavo.padovan@collabora.com> > > When using explicit synchronization userspace needs to know if > the queue can deliver everything back in the same order, so we added > a new capability that drivers can use to report that they are capable > of keeping ordering. > > In videobuf2 core when using fences we also make sure to keep the ordering > of buffers, so if the driver guarantees it too the whole pipeline inside > V4L2 will be ordered and the V4L2_CAP_ORDERED should be used. > > Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.com> > --- > Documentation/media/uapi/v4l/vidioc-querycap.rst | 3 +++ > include/uapi/linux/videodev2.h | 1 + > 2 files changed, 4 insertions(+) > > diff --git a/Documentation/media/uapi/v4l/vidioc-querycap.rst b/Documentation/media/uapi/v4l/vidioc-querycap.rst > index 66fb1b3d6e6e..ed3daa814da9 100644 > --- a/Documentation/media/uapi/v4l/vidioc-querycap.rst > +++ b/Documentation/media/uapi/v4l/vidioc-querycap.rst > @@ -254,6 +254,9 @@ specification the ioctl returns an ``EINVAL`` error code. > * - ``V4L2_CAP_TOUCH`` > - 0x10000000 > - This is a touch device. > + * - ``V4L2_CAP_ORDERED`` > + - 0x20000000 > + - The device queue is ordered. > * - ``V4L2_CAP_DEVICE_CAPS`` > - 0x80000000 > - The driver fills the ``device_caps`` field. This capability can > diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h > index 185d6a0acc06..cd6fc1387f47 100644 > --- a/include/uapi/linux/videodev2.h > +++ b/include/uapi/linux/videodev2.h > @@ -459,6 +459,7 @@ struct v4l2_capability { > #define V4L2_CAP_STREAMING 0x04000000 /* streaming I/O ioctls */ > > #define V4L2_CAP_TOUCH 0x10000000 /* Is a touch device */ > +#define V4L2_CAP_ORDERED 0x20000000 /* Is the device queue ordered */ I guess we discussed that at the Linux Media summit. The problem of making it a global flag is that drivers may support ordered formats only for some of the formats. E. g., a driver that delivers both MPEG and RGB output formats may deliver ordered buffers for RGB, and unordered ones for MPEG. So, instead of doing a global format at v4l2_capability, it is probably better to use the flags field at struct v4l2_fmtdesc. That would allow userspace to know in advance what formats support it, by calling VIDIOC_ENUM_FMT. Regards, Mauro
2017-11-17 Mauro Carvalho Chehab <mchehab@osg.samsung.com>: > Em Wed, 15 Nov 2017 15:10:47 -0200 > Gustavo Padovan <gustavo@padovan.org> escreveu: > > > From: Gustavo Padovan <gustavo.padovan@collabora.com> > > > > When using explicit synchronization userspace needs to know if > > the queue can deliver everything back in the same order, so we added > > a new capability that drivers can use to report that they are capable > > of keeping ordering. > > > > In videobuf2 core when using fences we also make sure to keep the ordering > > of buffers, so if the driver guarantees it too the whole pipeline inside > > V4L2 will be ordered and the V4L2_CAP_ORDERED should be used. > > > > Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.com> > > --- > > Documentation/media/uapi/v4l/vidioc-querycap.rst | 3 +++ > > include/uapi/linux/videodev2.h | 1 + > > 2 files changed, 4 insertions(+) > > > > diff --git a/Documentation/media/uapi/v4l/vidioc-querycap.rst b/Documentation/media/uapi/v4l/vidioc-querycap.rst > > index 66fb1b3d6e6e..ed3daa814da9 100644 > > --- a/Documentation/media/uapi/v4l/vidioc-querycap.rst > > +++ b/Documentation/media/uapi/v4l/vidioc-querycap.rst > > @@ -254,6 +254,9 @@ specification the ioctl returns an ``EINVAL`` error code. > > * - ``V4L2_CAP_TOUCH`` > > - 0x10000000 > > - This is a touch device. > > + * - ``V4L2_CAP_ORDERED`` > > + - 0x20000000 > > + - The device queue is ordered. > > * - ``V4L2_CAP_DEVICE_CAPS`` > > - 0x80000000 > > - The driver fills the ``device_caps`` field. This capability can > > diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h > > index 185d6a0acc06..cd6fc1387f47 100644 > > --- a/include/uapi/linux/videodev2.h > > +++ b/include/uapi/linux/videodev2.h > > @@ -459,6 +459,7 @@ struct v4l2_capability { > > #define V4L2_CAP_STREAMING 0x04000000 /* streaming I/O ioctls */ > > > > #define V4L2_CAP_TOUCH 0x10000000 /* Is a touch device */ > > +#define V4L2_CAP_ORDERED 0x20000000 /* Is the device queue ordered */ > > I guess we discussed that at the Linux Media summit. > The problem of making it a global flag is that drivers may support > ordered formats only for some of the formats. E. g., a driver that > delivers both MPEG and RGB output formats may deliver ordered > buffers for RGB, and unordered ones for MPEG. > > So, instead of doing a global format at v4l2_capability, it is probably > better to use the flags field at struct v4l2_fmtdesc. > > That would allow userspace to know in advance what formats support > it, by calling VIDIOC_ENUM_FMT. Thanks for clarifying, Mauro. I'll work on making it part of v4l2_fmtdesc. Gustavo
diff --git a/Documentation/media/uapi/v4l/vidioc-querycap.rst b/Documentation/media/uapi/v4l/vidioc-querycap.rst index 66fb1b3d6e6e..ed3daa814da9 100644 --- a/Documentation/media/uapi/v4l/vidioc-querycap.rst +++ b/Documentation/media/uapi/v4l/vidioc-querycap.rst @@ -254,6 +254,9 @@ specification the ioctl returns an ``EINVAL`` error code. * - ``V4L2_CAP_TOUCH`` - 0x10000000 - This is a touch device. + * - ``V4L2_CAP_ORDERED`` + - 0x20000000 + - The device queue is ordered. * - ``V4L2_CAP_DEVICE_CAPS`` - 0x80000000 - The driver fills the ``device_caps`` field. This capability can diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h index 185d6a0acc06..cd6fc1387f47 100644 --- a/include/uapi/linux/videodev2.h +++ b/include/uapi/linux/videodev2.h @@ -459,6 +459,7 @@ struct v4l2_capability { #define V4L2_CAP_STREAMING 0x04000000 /* streaming I/O ioctls */ #define V4L2_CAP_TOUCH 0x10000000 /* Is a touch device */ +#define V4L2_CAP_ORDERED 0x20000000 /* Is the device queue ordered */ #define V4L2_CAP_DEVICE_CAPS 0x80000000 /* sets device capabilities field */