[PATCH V2 3/4] drm/panel: Add prepare_upstream_first flag to drm_panel

[Jagan Teki]

Hi Dave,

On Fri, Oct 7, 2022 at 6:26 PM Dave Stevenson
<dave.stevenson at raspberrypi.com> wrote:
>
> Hi Jagan
>
> On Thu, 6 Oct 2022 at 15:25, Jagan Teki <jagan at amarulasolutions.com> wrote:
> >
> > On Fri, Mar 4, 2022 at 8:48 PM Dave Stevenson
> > <dave.stevenson at raspberrypi.com> wrote:
> > >
> > > Mapping to the drm_bridge flag pre_enable_upstream_first,
> > > add a new flag prepare_upstream_first to drm_panel to allow
> > > the panel driver to request that the upstream bridge should
> > > be pre_enabled before the panel prepare.
> > >
> > > Signed-off-by: Dave Stevenson <dave.stevenson at raspberrypi.com>
> > > ---
> > >  drivers/gpu/drm/bridge/panel.c |  3 +++
> > >  include/drm/drm_panel.h        | 10 ++++++++++
> > >  2 files changed, 13 insertions(+)
> > >
> > > diff --git a/drivers/gpu/drm/bridge/panel.c b/drivers/gpu/drm/bridge/panel.c
> > > index 5be057575183..2ea08b3ba326 100644
> > > --- a/drivers/gpu/drm/bridge/panel.c
> > > +++ b/drivers/gpu/drm/bridge/panel.c
> > > @@ -234,6 +234,9 @@ struct drm_bridge *drm_panel_bridge_add_typed(struct drm_panel *panel,
> > >         panel_bridge->bridge.ops = DRM_BRIDGE_OP_MODES;
> > >         panel_bridge->bridge.type = connector_type;
> > >
> > > +       panel_bridge->bridge.pre_enable_upstream_first =
> > > +                                               panel->prepare_upstream_first;
> > > +
> >
> > panel_bridge is common for bridge users who used panel and those who
> > might not need upstream first, so better to handle per bridge user
> > whoever needs this.
>
> Sorry, I don't follow you.

panel_bridge driver is a common bridge for drm_panel_bridge_add
registered bridges. If we enable pre_enable_upstream_first globally in
panel_bridge driver then it affects panes that don't require
pre_enable first for that bridge chain. Hope you understand.

Thanks,
Jagan.