Re: [PATCH] drm/msm/dsi: Set panel orientation when directly connected

[Abhinav Kumar]

On 7/8/2022 1:58 PM, Dmitry Baryshkov wrote:
> On Fri, 8 Jul 2022 at 22:42, Abhinav Kumar <quic_abhinavk@xxxxxxxxxxx> wrote:
> > On 7/8/2022 9:00 AM, Abhinav Kumar wrote:
> > > On 7/8/2022 8:25 AM, Doug Anderson wrote:
> > > > Hi,
> > > >
> > > > On Wed, Jul 6, 2022 at 12:14 PM Stephen Boyd <swboyd@xxxxxxxxxxxx> wrote:
> > > > > Set the panel orientation in drm when the panel is directly connected,
> > > > > i.e. we're not using an external bridge. The external bridge case is
> > > > > already handled by the panel bridge code, so we only update the path we
> > > > > take when the panel is directly connected/internal. This silences a
> > > > > warning splat coming from __drm_mode_object_add() on Wormdingler boards.
> > > > >
> > > > > Cc: Hsin-Yi Wang <hsinyi@xxxxxxxxxxxx>
> > > > > Cc: Douglas Anderson <dianders@xxxxxxxxxxxx>
> > > > > Signed-off-by: Stephen Boyd <swboyd@xxxxxxxxxxxx>
> > > > > ---
> > > > >
> > > > > This relies on commit 5e41b01a7808 ("drm/panel: Add an API to allow drm
> > > > > to set orientation from panel") which is in drm-misc
> > > > >
> > > > >    drivers/gpu/drm/msm/dsi/dsi_manager.c | 2 ++
> > > > >    1 file changed, 2 insertions(+)
> > > >
> > > > I don't personally have objections to this, but (to my understanding)
> > > > "the future" is that everyone should use panel_bridge. If we made the
> > > > move to panel_bridge today then we wouldn't need to do this. In
> > > > general I think panel_bridge would end up letting us delete a bunch of
> > > > code...
> > > >
> > > > See commit 4e5763f03e10 ("drm/bridge: ti-sn65dsi86: Wrap panel with
> > > > panel-bridge") for when this was done by ti-sn65dsi86.
> > > >
> > > > Then again, I spent a small amount of time looking into this and it's
> > > > definitely non-trivial. Still likely worthwhile, but not worth
> > > > blocking a tiny fix like this. It also should be fairly obvious that
> > > > we should delete this when we switch to panel_bridge.
> > >
> > > Right, from what I saw on IRC, panel_bridge is the way forward and
> > > dmitry did push a change to do that
> > >
> > > https://patchwork.freedesktop.org/patch/492585/
> > >
> > > But I think we can go ahead with this change because its simple enough.
> > >
> > > Regarding the panel_bridge migration, I am going to start reviewing that
> > > as well.
> >
> > I did some more digging up on the panel_bridge migration.
> >
> > Dmitry has posted this towards december last year
> >
> > https://patches.linaro.org/project/dri-devel/patch/20211207222901.988484-3-dmitry.baryshkov@xxxxxxxxxx/
> >
> >
> > and I had given my R-b on this already in Jan.
> >
> > I am not sure why this change was dropped OR was not part of msm-next
> > already.
> >
> > Dmitry, any reason this change was left out so long and why the R-b was
> > not retained and this was reposted?
> >
> >   From what i can see the change looks identical.
>
> I don't remember if it is identical or not. Basically it was postponed
> to allow DSC to flow in. We used drm_panel to pass DSC pps data. And
> if we use panel-bridge, we don't get a handle of the panel.
> Later on I have posted the series moving DSC pps pointer from
> drm_panel to mipi_dsi_device (which is logical anyway, since it's not
> only the panel, who can provide the DSC pps info, some bridges can
> process DSC-compressed data). But since that time it received no
> feedback.

Thanks for the details.

I will try to review the DRM core bits. But I guess for them to land, we 
need some of the core maintainers to pitch in on that.


>