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

[Pandiyan, Dhinakaran]

On Wed, 2017-09-13 at 16:31 +0300, Ville Syrjälä wrote:
> 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.

That was the goal :) Then I decided to simplify the function a little
bit in patches 4, 5, 6 and 7 before working on modifying it's structure.

> 
> > 
> > Signed-off-by: Dhinakaran Pandiyan <dhinakaran.pandiyan at 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
>