[Intel-gfx] [PATCH 3/3] drm/i915: Implement Link Rate fallback on Link training failure

[Chris Wilson]

On Wed, Nov 30, 2016 at 09:36:33AM +0100, Daniel Vetter wrote:
> On Tue, Nov 29, 2016 at 11:30:33PM -0800, Manasi Navare wrote:
> > +static void intel_dp_modeset_retry_work_fn(struct work_struct *work)
> > +{
> > +	struct intel_connector *intel_connector;
> > +	struct drm_connector *connector;
> > +	struct drm_display_mode *mode;
> > +	bool verbose_prune = true;
> > +
> > +	intel_connector = container_of(work, typeof(*intel_connector),
> > +				       modeset_retry_work);
> > +	connector = &intel_connector->base;
> > +	DRM_DEBUG_KMS("[CONNECTOR:%d:%s]\n", connector->base.id,
> > +		      connector->name);
> > +
> > +	/* Grab the locks before changing connector property*/
> > +	mutex_lock(&connector->dev->mode_config.mutex);
> > +	/* Set connector link status to BAD and send a Uevent to notify
> > +	 * userspace to do a modeset.
> > +	 */
> > +	drm_mode_connector_set_link_status_property(connector,
> > +						    DRM_MODE_LINK_STATUS_BAD);
> > +	list_for_each_entry(mode, &connector->modes, head) {
> > +		mode->status = intel_dp_mode_valid(connector,
> > +						   mode);
> > +	}
> > +	drm_mode_prune_invalid(connector->dev, &connector->modes,
> > +			       verbose_prune);
> 
> This call to drm_mode_prune_invalid is probably just to paper over a bug
> in SNA - SNA violates the hotplug handling uabi by not unconditionally
> reprobing. Inconsistently paper over that bug in the kernel is not good,
> userspace interfaces need to be well defined. Please remove this call and
> test with either UXA or -modesetting until SNA is fixed.

Then you should also categorically state that (once again) misusing the
HOTPLUG uevent for notification of a property update is wrong.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre