Re: [PATCH v2] drm/i915/dp: Clean up intel_dp_check_mst_status

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

On Thu, 21 Sep 2017, Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com> wrote:
> Rewriting this code without the goto, I believe, makes it more readable.
> One functional change that has been included is the handling of failed ESI
> register reads. Instead of disabling MST only for the first failed read, we
> now disable MST on subsequent failed reads too. A failed ESI read is
> problematic irrespective of whether it is the first or not.
>
> v2: Don't ignore return from _mst_hpd_irq() (James)
>
> Cc: James Ausmus <james.ausmus@intel.com>
> Cc: Jani Nikula <jani.nikula@intel.com>
> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> Signed-off-by: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>

I pushed everything *except* this patch in the series, please repost in
a new thread for clean CI results.

Thanks,
Jani.


> ---
>  drivers/gpu/drm/i915/intel_dp.c | 78 ++++++++++++++++++-----------------------
>  1 file changed, 34 insertions(+), 44 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> index 98e7b96ca826..aa97bd825369 100644
> --- a/drivers/gpu/drm/i915/intel_dp.c
> +++ b/drivers/gpu/drm/i915/intel_dp.c
> @@ -4191,57 +4191,47 @@ static void intel_dp_handle_test_request(struct intel_dp *intel_dp)
>  static int
>  intel_dp_check_mst_status(struct intel_dp *intel_dp)
>  {
> -	bool bret;
> +	u8 esi[DP_DPRX_ESI_LEN] = { 0 };
> +	struct intel_digital_port *intel_dig_port = dp_to_dig_port(intel_dp);
>  
> -	if (intel_dp->is_mst) {
> -		u8 esi[DP_DPRX_ESI_LEN] = { 0 };
> -		int ret = 0;
> -		int retry;
> +	if (!intel_dp->is_mst)
> +		return -EINVAL;
> +
> +	while (intel_dp_get_sink_irq_esi(intel_dp, esi)) {
> +		int ret, retry;
>  		bool handled;
> -		bret = intel_dp_get_sink_irq_esi(intel_dp, esi);
> -go_again:
> -		if (bret == true) {
> -
> -			/* check link status - esi[10] = 0x200c */
> -			if (intel_dp->active_mst_links &&
> -			    !drm_dp_channel_eq_ok(&esi[10], intel_dp->lane_count)) {
> -				DRM_DEBUG_KMS("channel EQ not ok, retraining\n");
> -				intel_dp_start_link_train(intel_dp);
> -				intel_dp_stop_link_train(intel_dp);
> -			}
>  
> -			DRM_DEBUG_KMS("got esi %3ph\n", esi);
> -			ret = drm_dp_mst_hpd_irq(&intel_dp->mst_mgr, esi, &handled);
> -
> -			if (handled) {
> -				for (retry = 0; retry < 3; retry++) {
> -					int wret;
> -					wret = drm_dp_dpcd_write(&intel_dp->aux,
> -								 DP_SINK_COUNT_ESI+1,
> -								 &esi[1], 3);
> -					if (wret == 3) {
> -						break;
> -					}
> -				}
> +		DRM_DEBUG_KMS("ESI %3ph\n", esi);
>  
> -				bret = intel_dp_get_sink_irq_esi(intel_dp, esi);
> -				if (bret == true) {
> -					DRM_DEBUG_KMS("got esi2 %3ph\n", esi);
> -					goto go_again;
> -				}
> -			} else
> -				ret = 0;
> +		/* check link status - esi[10] = 0x200c */
> +		if (intel_dp->active_mst_links &&
> +		    !drm_dp_channel_eq_ok(&esi[10], intel_dp->lane_count)) {
> +			intel_dp_start_link_train(intel_dp);
> +			intel_dp_stop_link_train(intel_dp);
> +		}
>  
> -			return ret;
> -		} else {
> -			struct intel_digital_port *intel_dig_port = dp_to_dig_port(intel_dp);
> -			DRM_DEBUG_KMS("failed to get ESI - device may have failed\n");
> -			intel_dp->is_mst = false;
> -			drm_dp_mst_topology_mgr_set_mst(&intel_dp->mst_mgr, intel_dp->is_mst);
> -			/* send a hotplug event */
> -			drm_kms_helper_hotplug_event(intel_dig_port->base.base.dev);
> +		ret = drm_dp_mst_hpd_irq(&intel_dp->mst_mgr, esi, &handled);
> +		if (!handled)
> +			return 0;
> +
> +		if (ret)
> +			DRM_DEBUG_KMS("error handling MST IRQ_HPD %d\n", ret);
> +
> +		for (retry = 0; retry < 3; retry++) {
> +			int wret;
> +
> +			wret = drm_dp_dpcd_write(&intel_dp->aux,
> +						 DP_SINK_COUNT_ESI + 1, &esi[1],
> +						 3);
> +			if (wret == 3)
> +				break;
>  		}
>  	}
> +
> +	DRM_DEBUG_KMS("failed to get ESI - device may have failed\n");
> +	intel_dp->is_mst = false;
> +	drm_dp_mst_topology_mgr_set_mst(&intel_dp->mst_mgr, intel_dp->is_mst);
> +	drm_kms_helper_hotplug_event(intel_dig_port->base.base.dev);
>  	return -EINVAL;
>  }

-- 
Jani Nikula, Intel Open Source Technology Center
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