Em Wed, 29 Mar 2017 09:56:47 +0200 Hans Verkuil <hverkuil@xxxxxxxxx> escreveu: > The documentation for video capture and output devices claims that the video standard > ioctls are required. This is not the case, they are only required for PAL/NTSC/SECAM > type inputs and outputs. Sensors do not implement this at all and e.g. HDMI inputs > implement the DV Timings ioctls. > > Just drop the mention of 'video standard' ioctls. > > Signed-off-by: Hans Verkuil <hans.verkuil@xxxxxxxxx> This is an API change that has the potential of breaking userspace. In the past, several applications were failing if VIDIOC_ENUMSTD ioctl is not implemented. So, I remember we had this discussion before, but I don't remember the dirty details anymore. Yet, looking at the code, it seems that we ended by making VIDIOC_ENUMSTD mandatory and implemented at the core. So, V4L2 core will make this ioctl available for all drivers. The core implementattion will, however, return -ENODATA if the driver doesn't set video_device.tvnorms, indicating that standard video timings are not supported. So, instead of the enclosed patch, the documentation should mention the standard ioctls, saying that G_STD/S_STD are optional, and ENUMSTD is mandatory. We could include a note about it may return -ENODATA, although the ENUMSTD documentation already states that it returns -ENODATA: https://linuxtv.org/downloads/v4l-dvb-apis-new/uapi/v4l/vidioc-enumstd.html Regards, Mauro > --- > diff --git a/Documentation/media/uapi/v4l/dev-capture.rst b/Documentation/media/uapi/v4l/dev-capture.rst > index 32b32055d070..4218742ab5d9 100644 > --- a/Documentation/media/uapi/v4l/dev-capture.rst > +++ b/Documentation/media/uapi/v4l/dev-capture.rst > @@ -42,8 +42,8 @@ Video capture devices shall support :ref:`audio input <audio>`, > :ref:`tuner`, :ref:`controls <control>`, > :ref:`cropping and scaling <crop>` and > :ref:`streaming parameter <streaming-par>` ioctls as needed. The > -:ref:`video input <video>` and :ref:`video standard <standard>` > -ioctls must be supported by all video capture devices. > +:ref:`video input <video>` ioctls must be supported by all video > +capture devices. > > > Image Format Negotiation > diff --git a/Documentation/media/uapi/v4l/dev-output.rst b/Documentation/media/uapi/v4l/dev-output.rst > index 25ae8ec96fdf..342eb4931f5c 100644 > --- a/Documentation/media/uapi/v4l/dev-output.rst > +++ b/Documentation/media/uapi/v4l/dev-output.rst > @@ -40,8 +40,8 @@ Video output devices shall support :ref:`audio output <audio>`, > :ref:`modulator <tuner>`, :ref:`controls <control>`, > :ref:`cropping and scaling <crop>` and > :ref:`streaming parameter <streaming-par>` ioctls as needed. The > -:ref:`video output <video>` and :ref:`video standard <standard>` > -ioctls must be supported by all video output devices. > +:ref:`video output <video>` ioctls must be supported by all video > +output devices. > > > Image Format Negotiation Thanks, Mauro
