Re: [PATCH 3/3] drm/i915: force full detect on sink count change

[Jani Nikula <jani.nikula@linux.intel.com>]

On Tue, 25 Aug 2015, Sivakumar Thulasimani <sivakumar.thulasimani@intel.com> wrote:
> From: "Thulasimani,Sivakumar" <sivakumar.thulasimani@intel.com>
>
> This patch checks for changes in sink count between short pulse
> hpds and forces full detect when there is a change. This will
> result in compliance test case 4.2.2.8 passing since it tests
> for this behavior.
>
> This will allow both detection of hotplug and unplug of panels
> through dongles that give only short pulse for such events.
>
> Signed-off-by: Sivakumar Thulasimani <sivakumar.thulasimani@intel.com>
> ---
>  drivers/gpu/drm/i915/intel_dp.c |   20 ++++++++++++++++----
>  1 file changed, 16 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> index 834f513..eb3ab41 100644
> --- a/drivers/gpu/drm/i915/intel_dp.c
> +++ b/drivers/gpu/drm/i915/intel_dp.c
> @@ -4370,26 +4370,34 @@ go_again:
>   *  4. Check link status on receipt of hot-plug interrupt
>   */
>  static void
> -intel_dp_check_link_status(struct intel_dp *intel_dp)
> +intel_dp_check_link_status(struct intel_dp *intel_dp, bool *perform_full_detect)

You could turn perform_full_detect into a boolean return value which
this function doesn't have.

>  {
>  	struct drm_device *dev = intel_dp_to_dev(intel_dp);
>  	struct intel_encoder *intel_encoder = &dp_to_dig_port(intel_dp)->base;
>  	struct intel_crtc *crtc =
>  		to_intel_crtc(dp_to_dig_port(intel_dp)->base.base.crtc);
>  	u8 sink_irq_vector;
> +	u8 old_sink_count = intel_dp->sink_count;
> +	u8 ret;

Isn't this a bool, really?

>  	u8 link_status[DP_LINK_STATUS_SIZE];
>  
>  	WARN_ON(!drm_modeset_is_locked(&dev->mode_config.connection_mutex));
>  
> +	*perform_full_detect = false;
> +
>  	/* Try to read receiver status if the link appears to be up */
>  	if (!intel_dp_get_link_status(intel_dp, link_status)) {
>  		return;
>  	}
>  
>  	/* Now read the DPCD to see if it's actually running */
> -	if (!intel_dp_get_dpcd(intel_dp)) {
> +	ret = intel_dp_get_dpcd(intel_dp);
> +
> +	if (old_sink_count != intel_dp->sink_count)
> +		*perform_full_detect = true;

Can't trust intel_dp->sink_count without checking the return value. So I
guess you can call intel_dp_get_dpcd the way it's done now, and move the
sink count check below it.

BR,
Jani.

> +
> +	if (!ret)
>  		return;
> -	}
>  
>  	if (!intel_encoder->base.crtc)
>  		return;
> @@ -5031,13 +5039,17 @@ intel_dp_hpd_pulse(struct intel_digital_port *intel_dig_port, bool long_hpd)
>  		}
>  
>  		if (!intel_dp->is_mst) {
> +			bool full_detect;
>  			/*
>  			 * we'll check the link status via the normal hot plug path later -
>  			 * but for short hpds we should check it now
>  			 */
>  			drm_modeset_lock(&dev->mode_config.connection_mutex, NULL);
> -			intel_dp_check_link_status(intel_dp);
> +			intel_dp_check_link_status(intel_dp, &full_detect);
>  			drm_modeset_unlock(&dev->mode_config.connection_mutex);
> +
> +			if (full_detect)
> +				goto put_power;
>  		}
>  	}
>  
> -- 
> 1.7.9.5
>

-- 
Jani Nikula, Intel Open Source Technology Center
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