Re: [PATCH 5/9] drm/i915/dp: Remove intel_dp->is_mst check in intel_dp_check_mst_status

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Tue, Sep 12, 2017 at 04:57:26PM -0700, Dhinakaran Pandiyan wrote:
> There is just only one caller now, which already checks for
> intel_dp->is_mst. So, remove this and fix some braces while at it.

Hmm. So this depends on the subtle detail that
drm_dp_mst_topology_mgr_resume() will "fail" if didn't enable mst
prior to calling it. That fact isn't obvious at all, so I would
suggest noting that in the commit message at least (maybe we should
even have a comment in the code?)

I'm assuming there are not other changes beyond just dropping the
top level 'if (mst) { }' thing? This is one reason I prefer flat code.
If the function had been flat to begin with the diff would have
actually turned out legible. IIRC I even posted a flattening patch at
some point but I guess it didn't go in. I would suggest that you take
the opportunity to flatten out the rest of this function while you
in the neighbourhood.

> 
> Signed-off-by: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
> ---
>  drivers/gpu/drm/i915/intel_dp.c | 85 ++++++++++++++++++++---------------------
>  1 file changed, 42 insertions(+), 43 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> index b3d95cb7546b..3f2ca10ccbcd 100644
> --- a/drivers/gpu/drm/i915/intel_dp.c
> +++ b/drivers/gpu/drm/i915/intel_dp.c
> @@ -4192,57 +4192,56 @@ static int
>  intel_dp_check_mst_status(struct intel_dp *intel_dp)
>  {
>  	bool bret;
> +	u8 esi[DP_DPRX_ESI_LEN] = { 0 };
> +	int ret = 0;
> +	int retry;
> +	bool handled;
>  
> -	if (intel_dp->is_mst) {
> -		u8 esi[DP_DPRX_ESI_LEN] = { 0 };
> -		int ret = 0;
> -		int retry;
> -		bool handled;
> -		bret = intel_dp_get_sink_irq_esi(intel_dp, esi);
> +	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);
> -			}
> +	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("got esi %3ph\n", esi);
> +		ret = drm_dp_mst_hpd_irq(&intel_dp->mst_mgr, esi, &handled);
>  
> -				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;
> +		if (handled) {
> +			for (retry = 0; retry < 3; retry++) {
> +				int wret;
>  
> -			return ret;
> +				wret = drm_dp_dpcd_write(&intel_dp->aux,
> +							 DP_SINK_COUNT_ESI+1,
> +							 &esi[1], 3);
> +				if (wret == 3)
> +					break;
> +			}
> +
> +			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 {
> -			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 = 0;
>  		}
> +	} 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);
> +		drm_kms_helper_hotplug_event(intel_dig_port->base.base.dev);
> +		ret = -EINVAL;
>  	}
> -	return -EINVAL;
> +	return ret;
>  }
>  
>  static void
> -- 
> 2.11.0

-- 
Ville Syrjälä
Intel OTC
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