[Freedreno] [RFC PATCH 1/7] drm/msm/dp: fix panel bridge attachment

[Dmitry Baryshkov]

On Wed, 12 Jan 2022 at 20:41, Kuogee Hsieh <quic_khsieh at quicinc.com> wrote:
>
>
> On 1/6/2022 6:01 PM, Dmitry Baryshkov wrote:
> > In commit 8a3b4c17f863 ("drm/msm/dp: employ bridge mechanism for display
> > enable and disable") the DP driver received a drm_bridge instance, which
> > is always attached to the encoder as a root bridge. However it conflicts
> > with the panel_bridge support for eDP panels. Change panel_bridge
> > attachment to come after dp_bridge attachment.
> >
> > Fixes: 8a3b4c17f863 ("drm/msm/dp: employ bridge mechanism for display enable and disable")
> > Cc: Kuogee Hsieh <quic_khsieh at quicinc.com>
> > Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov at linaro.org>
> > ---
> >   drivers/gpu/drm/msm/dp/dp_drm.c | 21 +++++++++++----------
> >   1 file changed, 11 insertions(+), 10 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/msm/dp/dp_drm.c b/drivers/gpu/drm/msm/dp/dp_drm.c
> > index d4d360d19eba..26ef41a4c1b6 100644
> > --- a/drivers/gpu/drm/msm/dp/dp_drm.c
> > +++ b/drivers/gpu/drm/msm/dp/dp_drm.c
> > @@ -169,16 +169,6 @@ struct drm_connector *dp_drm_connector_init(struct msm_dp *dp_display)
> >
> >       drm_connector_attach_encoder(connector, dp_display->encoder);
> >
> > -     if (dp_display->panel_bridge) {
> > -             ret = drm_bridge_attach(dp_display->encoder,
> > -                                     dp_display->panel_bridge, NULL,
> > -                                     DRM_BRIDGE_ATTACH_NO_CONNECTOR);
> > -             if (ret < 0) {
> > -                     DRM_ERROR("failed to attach panel bridge: %d\n", ret);
> > -                     return ERR_PTR(ret);
> > -             }
> > -     }
> > -
> >       return connector;
> >   }
> >
> > @@ -246,5 +236,16 @@ struct drm_bridge *msm_dp_bridge_init(struct msm_dp *dp_display, struct drm_devi
> >               return ERR_PTR(rc);
> >       }
> >
>
> can check connector_type here and if connector_type ==
> DRM_MODE_CONNECTOR_eDP then no drm_bridge  add to eDP?  So that eDP only
> has panel_bridge and DP only has drm_bridge?

No, we still need the DP bridge for the eDP. It handles modesetting,
enabling and disabling of the DP controller, etc.

>
> is this fix all your concerns?
>
>
> > +     if (dp_display->panel_bridge) {
> > +             rc = drm_bridge_attach(dp_display->encoder,
> > +                                     dp_display->panel_bridge, bridge,
> > +                                     DRM_BRIDGE_ATTACH_NO_CONNECTOR);
> > +             if (rc < 0) {
> > +                     DRM_ERROR("failed to attach panel bridge: %d\n", rc);
> > +                     drm_bridge_remove(bridge);
> > +                     return ERR_PTR(rc);
> > +             }
> > +     }
> > +
> >       return bridge;
> >   }



-- 
With best wishes
Dmitry