Hi Hans, On Fri, Apr 26, 2024 at 09:22:40AM +0200, Hans Verkuil wrote: > On 20/02/2024 14:03, Sakari Ailus wrote: > > When a device passes through the video data while still having its own > > receiver and transmitter, it can use the same frequency as the upstream > > link does. The Intel MEI CSI device is an example of this. An integer menu > > control isn't useful in conveying the actual frequency to the receiver in > > this case. > > > > Document that the LINK_FREQ control may also be a 64-bit integer control. > > > > Signed-off-by: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx> > > --- > > .../userspace-api/media/v4l/ext-ctrls-image-process.rst | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/Documentation/userspace-api/media/v4l/ext-ctrls-image-process.rst b/Documentation/userspace-api/media/v4l/ext-ctrls-image-process.rst > > index b1c2ab2854af..7a3ccb100e1d 100644 > > --- a/Documentation/userspace-api/media/v4l/ext-ctrls-image-process.rst > > +++ b/Documentation/userspace-api/media/v4l/ext-ctrls-image-process.rst > > @@ -22,7 +22,7 @@ Image Process Control IDs > > > > .. _v4l2-cid-link-freq: > > > > -``V4L2_CID_LINK_FREQ (integer menu)`` > > +``V4L2_CID_LINK_FREQ (integer menu or 64-bit integer)`` > > The frequency of the data bus (e.g. parallel or CSI-2). > > I really think a new control should be created for this. > > As I understand it, V4L2_CID_LINK_FREQ gives a set of supported frequencies, > and the application has to pick one (I think?). Is it supposed to be a > read-only control? Some driver seem to set the READ_ONLY flag, and some do not. > The documentation isn't helpful in that respect. This is read-only effectively in current IVSC implementation. > > In the case of the Intel MEI CSI and similar devices a new control would be > better, I think. Do I understand it correctly that for these devices it would > always be a read-only control? I.e. it just reports the frequency, but applications > cannot change it? How would you call the new control? V4L2_CID_LINK_FREQ_READ_ONLY? Originally the reason for changing LINK_FREQ for sensors was be part of changing sensor's configuration to achieve a given frame interval. -- Regards, Sakari Ailus
