[PATCH v3 1/6] drm: bridge: Propagate the bus flags from bridge->timings

[Nikhil Devshatwar]

On 20:59-20201130, Laurent Pinchart wrote:
> Hi Tomi,
> 
> On Mon, Nov 30, 2020 at 12:04:27PM +0200, Tomi Valkeinen wrote:
> > On 30/11/2020 12:02, Tomi Valkeinen wrote:
> > > On 30/11/2020 11:47, Laurent Pinchart wrote:
> > > 
> > >>>> Hasn't Boris commented in his review of v1 that bus flags should be set
> > >>>> in atomic_check, even when they're static ? We're moving towards
> > >>>> removing timings->input_bus_flags, so this patch goes in the wrong
> > >>>> direction :-S
> > >>>
> > >>> We have atomic_check only if the bridge has implemented atomic funcs. And even if there's
> > >>> atomic_check, not all bridges set the bus_flags there. So we need to either 1) fix the issue for now
> > >>> as in this patch, or 2) convert all bridges to use atomic funcs and fix all the bridges to set the
> > >>> bus_flags.
> > >>
> > >> The second option is what we'd like to achieve. Wouldn't it be best to
> > >> already start going in that direction ? We don't need to convert all
> > >> bridge drivers in one go here, just the ones that are used by tidss.

I took this as a future approach to eventually start supporting
atomic_funcs.
I will respin v4 of this series with updates to the other bridges
supporting atomic functions.

Nikhil Devshatwar

> > > 
> > > I think that sounds fine, except that this is blocking the DisplayPort support for J7. We have
> > > everything in for DP except dts changes (can be added only when the drivers work), and the connector
> > > stuff.
> > > 
> > > The connector stuff includes this series (so that tidss supports the new connector model), and
> > > "[PATCH RESEND v3 0/2] drm: add DisplayPort connector", which adds the connector driver.
> > > 
> > > The bridges currently used (that I know of) with tidss are cdns-mhdp, tfp410 and sii9022. I don't
> > > expect converting those would be a huge job, but I'd still really like to get the DP working in
> > > upstream without starting to expand the scope of the patches we need to enable it.
> > > 
> > > That said, we missed 5.11 so perhaps we have the time.
> 
> If there's not enough time to address the bridges, I'm fine with this
> series assuming the bridge changes will go on top. If we have enough
> time, let's go for it :-)
> 
> > Looks like Boris was missing from Cc in this series. Adding him.
> 
> -- 
> Regards,
> 
> Laurent Pinchart