Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx> wrote on Wed [2019-Oct-02 15:35:13 +0300]: > Hi Benoit, > > On Wed, Oct 02, 2019 at 07:14:38AM -0500, Benoit Parrot wrote: > > Hi Jacopo, > > > > Maybe, I miss spoke when I mentioned a helper I did not intent a framework > > level generic function. Just a function to help in this case :) > > > > That being said, I re-read the thread you mentioned. And as Hughes pointed > > out dynamically generating a "working" link frequency value which can be > > used by a CSI2 receiver to properly configure its PHY is not trivial. > > > > When I created this patch, I also had another to add V4L2_CID_LINK_FREQ > > support. I am testing this against the TI CAL CSI2 receiver, which already > > uses the V4L2_CID_PIXEL_RATE value for that purpose, so I also had a patch > > to add support for V4L2_CID_LINK_FREQ to that driver as well. > > > > Unfortunately, similar to Hughes' findings I was not able to make it "work" > > with all supported resolution/framerate. > > > > Unlike my V4L2_CID_PIXEL_RATE solution which now works in all mode with the > > same receiver. > > > > So long story short I dropped the V4L2_CID_LINK_FREQ patch and focused on > > V4L2_CID_PIXEL_RATE instead. > > It shouldn't make a difference which one you use; if you know the bus type > (and if it's CSI-2 with D-PHY, number of lanes and how many bits per pixel > the media bus format has), you can convert fairly trivially between the > two. Sakari, Yes I get that, but at this point as they say I will leave that as an exercise to the reader... Benoit > > -- > Sakari Ailus > sakari.ailus@xxxxxxxxxxxxxxx
