linux-kernel - Re: [PATCH 4/4] drm/bridge: ti-sn65dsi86: Add NO

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Message-ID: <CAF6AEGt8K=iy8=dn+GJxt7ybfPtGDPy9w3StqWDwyOv_CKLNVg@mail.gmail.com>
Date:   Mon, 20 Sep 2021 11:32:02 -0700
From:   Rob Clark <robdclark@...il.com>
To:     Doug Anderson <dianders@...omium.org>
Cc:     Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        linux-arm-msm <linux-arm-msm@...r.kernel.org>,
        freedreno <freedreno@...ts.freedesktop.org>,
        Stephen Boyd <swboyd@...omium.org>,
        Rob Clark <robdclark@...omium.org>,
        Andrzej Hajda <a.hajda@...sung.com>,
        Neil Armstrong <narmstrong@...libre.com>,
        Robert Foss <robert.foss@...aro.org>,
        Jonas Karlman <jonas@...boo.se>,
        Jernej Skrabec <jernej.skrabec@...il.com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 4/4] drm/bridge: ti-sn65dsi86: Add NO_CONNECTOR support

On Thu, Aug 12, 2021 at 1:08 PM Doug Anderson <dianders@...omium.org> wrote:
>
> Laurent,
>
> On Thu, Aug 12, 2021 at 12:26 PM Laurent Pinchart
> <laurent.pinchart@...asonboard.com> wrote:
> >
> > Hi Rob,
> >
> > Thank you for the patch.
> >
> > On Wed, Aug 11, 2021 at 04:52:50PM -0700, Rob Clark wrote:
> > > From: Rob Clark <robdclark@...omium.org>
> > >
> > > Slightly awkward to fish out the display_info when we aren't creating
> > > own connector.  But I don't see an obvious better way.
> >
> > We need a bit more than this, to support the NO_CONNECTOR case, the
> > bridge has to implement a few extra operations, and set the bridge .ops
> > field. I've submitted two patches to do so a while ago:
> >
> > - [RFC PATCH 08/11] drm/bridge: ti-sn65dsi86: Implement bridge connector operations ([1])
>
> Rob asked me about this over IRC, so if he left it out and it's needed
> then it's my fault. However, I don't believe it's needed until your
> series making this bridge chip support full DP. For the the eDP case
> the bridge chip driver in ToT no longer queries the EDID itself. It
> simply provides an AUX bus to the panel driver and the panel driver
> queries the EDID. I think that means we don't need to add
> DRM_BRIDGE_OP_EDID, right?
>
> I was also wondering if in the full DP case we should actually model
> the physical DP jack as a drm_bridge and have it work the same way. It
> would get probed via the DP AUX bus just like a panel. I seem to
> remember Stephen Boyd was talking about modeling the DP connector as a
> drm_bridge because it would allow us to handle the fact that some TCPC
> chips could only support HBR2 whereas others could support HBR3. Maybe
> it would end up being a fairly elegant solution?
>
> > - [RFC PATCH 09/11] drm/bridge: ti-sn65dsi86: Make connector creation optional ([2])
> >
> > The second patch is similar to the first half of this patch, but misses
> > the cleanup code. I'll try to rebase this and resubmit, but it may take
> > a bit of time.
>
> Whoops! You're right that Rob's patch won't work at all because we'll
> just hit the "Fix bridge driver to make connector optional!" case. I
> should have noticed that. :(

Yes, indeed.. once I fix that, I get no display..

Not sure if Laurent is still working on his series, otherwise I can
try to figure out what bridge ops are missing

BR,
-R