Re: [v3] drm/i915: Add detection of changing of edid on between suspend and resume

[Mika Kahola <mika.kahola@intel.com>]

On Fri, 2018-08-10 at 13:02 +0000, Lisovskiy, Stanislav wrote:
> On Thu, 2018-08-09 at 14:13 +0300, Gwan-gyeong Mun wrote:
> > 
> > The hotplug detection routine of i915 uses
> > drm_helper_hpd_irq_event(). This
> > helper can detect changing of status of connector, but it can not
> > detect
> > changing of edid.
> > 
> > Following scenario requires detection of changing of edid.
> > 
> >  1) plug display device to a connector
> >  2) system suspend
> >  3) unplug 1)'s display device and plug the other display device to
> > a
> > connector
> >  4) system resume
> > 
> > It adds edid check routine when a connector status still remains as
> > "connector_status_connected".
> > 
> > v2: Add NULL check before comparing of EDIDs.
> > 
> > Testcase: igt/kms_chamelium/hdmi-edid-change-during-hibernate
> > Testcase: igt/kms_chamelium/hdmi-edid-change-during-suspend
> > Testcase: igt/kms_chamelium/dp-edid-change-during-hibernate
> > Testcase: igt/kms_chamelium/dp-edid-change-during-suspend
> > 
> > Signed-off-by: Gwan-gyeong Mun <gwan-gyeong.mun@intel.com>
> > ---
> >  drivers/gpu/drm/i915/intel_hotplug.c | 84
> > +++++++++++++++++++++++++++-
> >  1 file changed, 83 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/intel_hotplug.c
> > b/drivers/gpu/drm/i915/intel_hotplug.c
> > index 648a13c6043c..965f2d771fc0 100644
> > --- a/drivers/gpu/drm/i915/intel_hotplug.c
> > +++ b/drivers/gpu/drm/i915/intel_hotplug.c
> > @@ -507,6 +507,88 @@ void intel_hpd_init(struct drm_i915_private
> > *dev_priv)
> >  	}
> >  }
> >  
> > +/**
> > + * intel_hpd_irq_event - hotplug processing
> > + * @dev: drm_device
> > + *
> > + * Drivers can use this function to run a detect cycle on all
> > connectors which
> > + * have the DRM_CONNECTOR_POLL_HPD flag set in their &polled
> > member.
> > All other
> > + * connectors are ignored, which is useful to avoid reprobing
> > fixed
> > panels.
> > + *
> > + * This function is useful for drivers which can't or don't track
> > hotplug interrupts
> > + * for each connector. This function is based on
> > drm_helper_hpd_irq_event() helper
> > + * function and besides it adds edid check routine when a
> > connector
> > status still
> > + * remains as "connector_status_connected".
> > + *
> > + * Following scenario requires detection of changing of edid.
> > + *  1) plug display device to a connector
> > + *  2) system suspend
> > + *  3) unplug 1)'s display device and plug the other display
> > device
> > to a connector
> > + *  4) system resume
> > +
> > + * This function must be called from process context with no mode
> > + * setting locks held.
> > + *
> > + * Note that a connector can be both polled and probed from the
> > hotplug handler,
> > + * in case the hotplug interrupt is known to be unreliable.
> > + */
> > +static bool intel_hpd_irq_event(struct drm_device *dev)
> > +{
> > +	struct drm_connector *connector;
> > +	struct drm_connector_list_iter conn_iter;
> > +	enum drm_connector_status old_status, cur_status;
> > +	struct edid *old_edid;
> > +	bool changed = false;
> > +
> > +	if (!dev->mode_config.poll_enabled)
> > +		return false;
> > +
> > +	mutex_lock(&dev->mode_config.mutex);
> > +	drm_connector_list_iter_begin(dev, &conn_iter);
> > +	drm_for_each_connector_iter(connector, &conn_iter) {
> > +		/* Only handle HPD capable connectors. */
> > +		if (!(connector->polled & DRM_CONNECTOR_POLL_HPD))
> > +			continue;
> > +
> > +		old_status = connector->status;
> > +		old_edid = to_intel_connector(connector)-
> > > 
> > > detect_edid;
> > +
> > +		cur_status = drm_helper_probe_detect(connector,
> > NULL, false);
> > +		DRM_DEBUG_KMS("[CONNECTOR:%d:%s] status updated
> > from
> > %s to %s\n",
> > +			      connector->base.id, connector->name,
> > +			      drm_get_connector_status_name(old_st
> > at
> > us),
> > +			      drm_get_connector_status_name(cur_st
> > at
> > us));
> > +
> > +		if (old_status != cur_status)
> > +			changed = true;
> > +
> > +		/* Check changing of edid when a connector status
> > still remains
> > +		 * as "connector_status_connected".
> > +		 */
> > +		if (old_status == cur_status &&
> > +		    cur_status == connector_status_connected) {
> > +			struct edid *cur_edid =
> > to_intel_connector(connector)->detect_edid;
> > +
> > +			if (!old_edid || !cur_edid)
> > +				continue;
> > +
> > +			if (memcmp(old_edid, cur_edid,
> > sizeof(*cur_edid))) {
> > +				changed = true;
> > +				DRM_DEBUG_KMS("[CONNECTOR:%d:%s]
> > edid updated\n",
> > +					      connector->base.id,
> > +					      connector->name);
> > +			}
> > +		}
> > +	}
> > +	drm_connector_list_iter_end(&conn_iter);
> > +	mutex_unlock(&dev->mode_config.mutex);
> > +
> > +	if (changed)
> > +		drm_kms_helper_hotplug_event(dev);
> > +
> > +	return changed;
> > +}
> > +
> >  static void i915_hpd_poll_init_work(struct work_struct *work)
> >  {
> >  	struct drm_i915_private *dev_priv =
> > @@ -552,7 +634,7 @@ static void i915_hpd_poll_init_work(struct
> > work_struct *work)
> >  	 * in the middle of disabling polling
> >  	 */
> >  	if (!enabled)
> > -		drm_helper_hpd_irq_event(dev);
> > +		intel_hpd_irq_event(dev);
> >  }
> Just wondering, as I saw previously drm_helper_hpd_irq_event function
> was used, which basically does the same thing, except doing memcmp
> for detecting the edid change. Is it only Intel specific change? As
> we
> could just add this modification to existing helper function or add
> another helper function to the drm (drm_probe_helper.c), so that it
> is
> also usable elsewhere..
I second Stanislav's proposal to add this feature as part of drm. This
edid check could be part of existing drm_helper_hpd_irq_event()
function. Other drivers might find this change useful.

> 
> > 
> >  
> >  /**
> -- 
> Best Regards,
> 
> Lisovskiy Stanislav
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/intel-gfx
-- 
Mika Kahola - Intel OTC

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