Hi Hans, On Friday, 25 August 2017 11:59:40 EEST Hans Verkuil wrote: > On 24/08/17 14:07, Mauro Carvalho Chehab wrote: > > From: "mchehab@xxxxxxxxxxxxxxxx" <mchehab@xxxxxxxxxxxxxxxx> > > > > When we added support for omap3, back in 2010, we added a new > > type of V4L2 devices that aren't fully controlled via the V4L2 > > device node. Yet, we never made it clear, at the V4L2 spec, > > about the differences between both types. > > > > Let's document them with the current implementation. > > > > Signed-off-by: Mauro Carvalho Chehab <mchehab@xxxxxxxxxxxxxxxx> > > Signed-off-by: Mauro Carvalho Chehab <mchehab@xxxxxxxxxxxxxxx> > > --- > > > > Documentation/media/uapi/v4l/open.rst | 47 ++++++++++++++++++++++++++++++ > > 1 file changed, 47 insertions(+) > > > > diff --git a/Documentation/media/uapi/v4l/open.rst > > b/Documentation/media/uapi/v4l/open.rst index afd116edb40d..cf522d9bb53c > > 100644 > > --- a/Documentation/media/uapi/v4l/open.rst > > +++ b/Documentation/media/uapi/v4l/open.rst > > @@ -6,6 +6,53 @@ > > > > Opening and Closing Devices > > *************************** > > > > +Types of V4L2 device control > > I don't like calling this 'device control'. Mostly because the word 'device' > can mean almost anything and is very overused. > > How about "hardware control"? The word device is used for different purposes that make the text unclear in my opinion. We have at least three different kinds of devices: - device node - kernel struct device (fortunately not relevant to the V4L2 API discussion) - hardware counterpart of the kernel struct device (SoC IP core, I2C chip, ...) - group of hardware devices that together make a larger user-facing functional device (for instance the SoC ISP IP cores and external camera sensors together make a camera device) We need different terms for those different concepts, and we need to be very consistent in our usage of those terms. I believe we should also define them formally at the beginning of the documentation to avoid confusion. [snip] -- Regards, Laurent Pinchart
