Re: [PATCH v3] drm/msm/dp: make eDP panel as the first connected connector

[Kuogee Hsieh]

On 7/6/2022 10:41 AM, Dmitry Baryshkov wrote:
> On 06/07/2022 20:38, Kuogee Hsieh wrote:
> > On 7/6/2022 10:25 AM, Dmitry Baryshkov wrote:
> > > On 06/07/2022 20:24, Kuogee Hsieh wrote:
> > > > Some userspace presumes that the first connected connector is the main
> > > > display, where it's supposed to display e.g. the login screen. For
> > > > laptops, this should be the main panel.
> > > >
> > > > This patch call drm_helper_move_panel_connectors_to_head() after
> > > > drm_bridge_connector_init() to make sure eDP stay at head of
> > > > connected connector list. This fixes unexpected corruption happen
> > > > at eDP panel if eDP is not placed at head of connected connector
> > > > list.
> > > >
> > > > Changes in v2:
> > > > -- move drm_helper_move_panel_connectors_to_head() to
> > > >         dpu_kms_drm_obj_init()
> > > >
> > > > Signed-off-by: Kuogee Hsieh <quic_khsieh@xxxxxxxxxxx>
> > > > ---
> > > >   drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c | 2 ++
> > > >   1 file changed, 2 insertions(+)
> > > >
> > > > diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c 
> > > > b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
> > > > index 2b9d931..50ff666 100644
> > > > --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
> > > > +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
> > > > @@ -763,6 +763,8 @@ static int _dpu_kms_drm_obj_init(struct dpu_kms 
> > > > *dpu_kms)
> > > >       if (ret)
> > > >           return ret;
> > > >   +    drm_helper_move_panel_connectors_to_head(dev);
> > >
> > > This should be in msm_drv.c unless you have a strong reason to have 
> > > it here.
> > Can you please  provide more info why should be in msm_drv.c?
>
> Let me quote my message from v1 review:
>
> Please move this call to the msm_drm_init(). Calling this function 
> somewhere after the ->kms_init() would make sure that all panel 
> connectors are close to the top of the list, whichever MDP/DPU driver 
> is used and whichever actual interface is bound to this panel.
Below are the call flow in timing order, ->kms_init does not create 
connectors/interfaces, hw_init does that.

1) ->kms_init

2) ->hw_init -> dpu_kms_hw_init --> _dpu_kms_drm_obj_init()  --> 
_dpu_kms_setup_displays()--> msm_dp_modeset_init() --> creator 
connectors/interfaces

3) drm_helper_move_panel_connectors_to_head() <== add here??

> > > _dpu_kms_drm_obj_init() create and initialize drm obj one by one and 
> > > _dpu_kms_setup_displays() had created system wide 
> > > connectors/interfaces .
> >
> > After that should be fine to move edp to head of connector list.
> >
> > > > +
> > > >       num_encoders = 0;
> > > >       drm_for_each_encoder(encoder, dev)
> > > >           num_encoders++;