[Intel-gfx] [PATCH] drm/fbdev: Fallback to non tiled mode if all tiles not present

[Manasi Navare]

On Wed, Nov 06, 2019 at 12:47:16PM +1000, Dave Airlie wrote:
> On Fri, 1 Nov 2019 at 07:46, Manasi Navare <manasi.d.navare at intel.com> wrote:
> >
> > In case of tiled displays, if we hotplug just one connector,
> > fbcon currently just selects the preferred mode and if it is
> > tiled mode then that becomes a problem if rest of the tiles are
> > not present.
> > So in the fbdev driver on hotplug when we probe the client modeset,
> > we we dont find all the connectors for all tiles, then on a connector
> > with one tile, just fallback to the first available non tiled mode
> > to display over a single connector.
> >
> > Suggested-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
> > Suggested-by: Dave Airlie <airlied at redhat.com>
> > Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
> > Cc: Dave Airlie <airlied at redhat.com>
> > Signed-off-by: Manasi Navare <manasi.d.navare at intel.com>
> > ---
> >  drivers/gpu/drm/drm_client_modeset.c | 29 ++++++++++++++++++++++++++++
> >  1 file changed, 29 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/drm_client_modeset.c b/drivers/gpu/drm/drm_client_modeset.c
> > index 895b73f23079..e28a723587db 100644
> > --- a/drivers/gpu/drm/drm_client_modeset.c
> > +++ b/drivers/gpu/drm/drm_client_modeset.c
> > @@ -114,6 +114,20 @@ drm_client_find_modeset(struct drm_client_dev *client, struct drm_crtc *crtc)
> >         return NULL;
> >  }
> >
> > +static struct drm_display_mode *
> > +drm_connector_fallback_non_tiled_mode(struct drm_connector *connector)
> > +{
> > +       struct drm_display_mode *mode;
> > +
> > +       list_for_each_entry(mode, &connector->modes, head) {
> > +               if (mode->hdisplay == connector->tile_h_size &&
> > +                   mode->vdisplay == connector->tile_v_size)
> > +                       continue;
> > +               return mode;
> > +       }
> > +       return NULL;
> > +}
> > +
> >  static struct drm_display_mode *
> >  drm_connector_has_preferred_mode(struct drm_connector *connector, int width, int height)
> >  {
> > @@ -348,8 +362,17 @@ static bool drm_client_target_preferred(struct drm_connector **connectors,
> >         struct drm_connector *connector;
> >         u64 conn_configured = 0;
> >         int tile_pass = 0;
> > +       int num_tiled_conns = 0;
> >         int i;
> >
> > +       for (i = 0; i < connector_count; i++) {
> > +               connector = connectors[i];
> > +               if (!connector->has_tile)
> > +                       continue;
> > +
> > +               num_tiled_conns ++;
> 
> Drop the space before the ++ here. Maybe just make this
> 
> if (connectors[i]->has_tile)
>         num_tiled_conns++;

Sure will modify like above and add your r-b afterwards.
Thank you so much for your review.

This only covers the hotplug case with 1 connector hotplugged and need to still
modify the fb dev code to ignore the second hotplug which I cant seem to figure out how
to avoid the second hotplug from going through a modeset and retain the first modeset on screen.

Also I will send a follow up patch to fallback to first non tiled mode in case of connected boot.
But its okay for that to be separate patch than this right?

Regards
Manasi

> 
> Reviewed-by: Dave Airlie <airlied at redhat.com>
> 
> Otherwise I think this seems fine, though it does beg the question in
> my mind of what happens if I get 2 8K monitors, and plug the first
> tile of one in, and the second tile of the other in.
> 
> Dave.