Hi Laurent, On Sun, Dec 15, 2024 at 07:02:40PM +0200, Laurent Pinchart wrote: > On Fri, Dec 13, 2024 at 07:15:55AM +0000, Sakari Ailus wrote: > > On Thu, Dec 12, 2024 at 05:53:53PM +0100, Jacopo Mondi wrote: > > > On Tue, Dec 10, 2024 at 09:59:04AM +0200, Sakari Ailus wrote: > > > > Add the get_mbus_config() as the means for conveying the link frequency > > > > towards the receiver drivers. > > > > > > > > Signed-off-by: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx> > > > > --- > > > > Documentation/driver-api/media/tx-rx.rst | 4 ++++ > > > > 1 file changed, 4 insertions(+) > > > > > > > > diff --git a/Documentation/driver-api/media/tx-rx.rst b/Documentation/driver-api/media/tx-rx.rst > > > > index dd09484df1d3..1430c330fd52 100644 > > > > --- a/Documentation/driver-api/media/tx-rx.rst > > > > +++ b/Documentation/driver-api/media/tx-rx.rst > > > > @@ -49,6 +49,10 @@ Link frequency > > > > The :ref:`V4L2_CID_LINK_FREQ <v4l2-cid-link-freq>` control is used to tell the > > > > receiver the frequency of the bus (i.e. it is not the same as the symbol rate). > > > > > > > > +On devices where the link frequency isn't configurable, the link_freq field of > > > > +struct v4l2_mbus_config is recommended over controls for conveying the link > > > > +frequency to the downstream driver in the pipeline. > > > > > > When read in its entirety, the paragraphs > > > > > > Link frequency > > > ^^^^^^^^^^^^^^ > > > > > > The :ref:`V4L2_CID_LINK_FREQ <v4l2-cid-link-freq>` control is used to tell the > > > receiver the frequency of the bus (i.e. it is not the same as the symbol rate). > > > > > > On devices where the link frequency isn't configurable, the link_freq field of > > > struct v4l2_mbus_config is recommended over controls for conveying the link > > > frequency. > > > > > > Sounds simpler without the last 7 words. > > > > > > A nit and just tastes maybe > > > > I used: > > > > On devices where the link frequency isn't configurable, using the ``link_freq`` > > field of struct v4l2_mbus_config is recommended over controls. > > Is it a recommendation for the transmitter driver or the receiver driver > ? If it's a recommendation for the transmitter driver, does that mean it > should not implement V4L2_CID_LINK_FREQ in that case ? How about the > need to expose the link frequency to userspace when it's fixed ? For the transmitter. Receivers do not implement get_mbus_config op. I can add a note on this. The only reason this has been exposed to the user space is because it's been a control that has been modifiable. Also HDMI to CSI-2 bridges work this way. The LINK_FREQ control is also an integer menu so the same control couldn't be used as-is. These were the reasons why the earlier review concluded with impelmenting this via get_mbus_config(). > > I think the documentation needs further clarification to clearly explain > what transmitters should do and what receivers should do. I can add this. > > > > > > > I like where this is going! > > > > > > Reviewed-by: Jacopo Mondi <jacopo.mondi@xxxxxxxxxxxxxxxx> > -- Regards, Sakari Ailus
