[Intel-gfx] [PATCH v2] drm/i915/dp: Update connector status for DP MST hotplugs

[Ville Syrjälä]

On Mon, Nov 07, 2016 at 04:27:30PM -0800, Dhinakaran Pandiyan wrote:
> Hotplugging a monitor in DP MST configuration triggers short pulses.
> Although the short pulse handling path ends up in the MST hotplug function,
> we do not perform a detect before sending the hotplug uvent. This leads to
> the connector status not being updated when the userspace calls
> DRM_IOCTL_MODE_GETCONNECTOR.
> 
> So, let's call the connector function ->detect() to update the connector
> status before sending the uevent.
> 
> v2: Update connector status inside mode_config mutex (Ville)
> 
> Signed-off-by: Dhinakaran Pandiyan <dhinakaran.pandiyan at intel.com>
> ---
>  drivers/gpu/drm/i915/intel_dp_mst.c | 22 +++++++++++++++++++++-
>  1 file changed, 21 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_dp_mst.c b/drivers/gpu/drm/i915/intel_dp_mst.c
> index 3ffbd69..8e36a96 100644
> --- a/drivers/gpu/drm/i915/intel_dp_mst.c
> +++ b/drivers/gpu/drm/i915/intel_dp_mst.c
> @@ -492,8 +492,28 @@ static void intel_dp_mst_hotplug(struct drm_dp_mst_topology_mgr *mgr)
>  	struct intel_dp *intel_dp = container_of(mgr, struct intel_dp, mst_mgr);
>  	struct intel_digital_port *intel_dig_port = dp_to_dig_port(intel_dp);
>  	struct drm_device *dev = intel_dig_port->base.base.dev;
> +	struct intel_connector *intel_connector;
> +	bool changed = false;
> +	enum drm_connector_status old_status;
> +	struct drm_mode_config *mode_config = &dev->mode_config;
> +
> +	mutex_lock(&mode_config->mutex);
> +	for_each_intel_connector(dev, intel_connector) {
> +		struct drm_connector *connector = &(intel_connector->base);
> +
> +		if (intel_connector->mst_port != intel_dp)
> +			continue;
> +
> +		old_status = connector->status;
> +		connector->status = connector->funcs->detect(connector, false);
> +
> +		if (old_status != connector->status)
> +			changed = true;
> +	}
> +	mutex_unlock(&mode_config->mutex);

To help reviewers it might be nice to have a short explanation of the
locking situation in the commit message, mainly why is it safe to simply
take mode_config.mutex here.

>  
> -	drm_kms_helper_hotplug_event(dev);
> +	if (changed)
> +		drm_kms_helper_hotplug_event(dev);
>  }
>  
>  static const struct drm_dp_mst_topology_cbs mst_cbs = {
> -- 
> 2.7.4

-- 
Ville Syrjälä
Intel OTC