[PATCH] drm/probe-helper: Fix modes reporting for writeback connector

[Alexandru-Cosmin Gheorghe]

On Thu, Jul 12, 2018 at 10:55:47AM +0200, Daniel Vetter wrote:
> On Thu, Jul 12, 2018 at 09:48:02AM +0100, Alexandru Gheorghe wrote:
> > Writeback connector is reported as disconnected, currently this causes
> > the setting of the edid property to null and then exit.
> > In order to properly get the modes for writeback we need to add an
> > exception when connector type is DRM_MODE_CONNECTOR_WRITEBACK.
> > 
> > Signed-off-by: Alexandru Gheorghe <alexandru-cosmin.gheorghe at arm.com>
> 
> Why do you even need a mode list for writeback?

It's used by userspace to know how big the writeback buffer could be.

> 
> Also, if you're already faking a mode list for the writeback connector,
> why can't you also fake it's connection status?
> -Daniel

AFAIK Reporting it as disconnected was a way of making sure it will be
ignored by userspace that's not aware of writeback connectorsa. Do you
think it's superfluous with DRM_CLIENT_CAP_WRITEBACK_CONNECTORS ?

> 
> > ---
> >  drivers/gpu/drm/drm_probe_helper.c | 3 ++-
> >  1 file changed, 2 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/gpu/drm/drm_probe_helper.c b/drivers/gpu/drm/drm_probe_helper.c
> > index 52774339..c7bdbe2 100644
> > --- a/drivers/gpu/drm/drm_probe_helper.c
> > +++ b/drivers/gpu/drm/drm_probe_helper.c
> > @@ -472,7 +472,8 @@ int drm_helper_probe_single_connector_modes(struct drm_connector *connector,
> >  
> >  	dev->mode_config.poll_running = drm_kms_helper_poll;
> >  
> > -	if (connector->status == connector_status_disconnected) {
> > +	if (connector->status == connector_status_disconnected &&
> > +	    connector->connector_type != DRM_MODE_CONNECTOR_WRITEBACK) {
> >  		DRM_DEBUG_KMS("[CONNECTOR:%d:%s] disconnected\n",
> >  			connector->base.id, connector->name);
> >  		drm_mode_connector_update_edid_property(connector, NULL);
> > -- 
> > 2.7.4
> > 
> > _______________________________________________
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> > dri-devel at lists.freedesktop.org
> > https://lists.freedesktop.org/mailman/listinfo/dri-devel
> 
> -- 
> Daniel Vetter
> Software Engineer, Intel Corporation
> http://blog.ffwll.ch

-- 
Cheers,
Alex G