Re: [PATCH] media: staging: max96712: Add support for 3-lane C-PHY

[Sakari Ailus <sakari.ailus@iki.fi>]

Hejssan, Niklas!

On Fri, Mar 31, 2023 at 03:24:04PM +0200, Niklas Söderlund wrote:
> Hej Sakari,
> 
> Tack för din feedback.
> 
> On 2023-03-31 15:21:34 +0300, Sakari Ailus wrote:
> 
> ...
> 
> > > @@ -332,8 +341,9 @@ static int max96712_parse_dt(struct 
> > > max96712_priv *priv)
> > >  {
> > >  	struct fwnode_handle *ep;
> > >  	struct v4l2_fwnode_endpoint v4l2_ep = {
> > > -		.bus_type = V4L2_MBUS_CSI2_DPHY
> > > +		.bus_type = V4L2_MBUS_UNKNOWN,
> > 
> > The bindings don't require setting bus-type. Please change the bindings as
> > well. And assume D-PHY in the driver if bus-type isn't set.
> 
> Thanks for spotting this, I will send out an update to update the 
> binding to require setting bus-type.
> 
> About updating the driver to assume D-PHY if bus-type is not set. I 
> wonder if we can avoid that and keep the driver change as is? The only 
> in-tree user of this binding is in r8a779a0-falcon-csi-dsi.dtsi, and I 
> intend to send out a patch to set the bus-type for that together with 
> the updated bindings.
> 
> I have tested this driver change on the Falcon board and if bus-type is 
> not explicitly set in the DTS it is reported as D-PHY and everything 
> works as expected. So if I
> 
> - Send out a patch to update the bindings to require bus-type being set.
> - Send out patch to update the only in-tree use of the driver to set 
>   bus-type.
> 
> Can't we avoid issues in the future by not assuming no bus-type is D-PHY 
> in the driver while still being backward compatible with the old DTS?

If you want to keep supporting D-PHY as a default, you should instead try
parsing with V4L2_MBUS_CSI2_DPHY as bus_type. Then CPHY if that fails.

Although if bus_type is mandatory, then this patch is fine.

-- 
Trevliga hälsningar,

Sakari Ailus