Re: [PATCH] drm/i915/dp_mst: Fix enabling pipe clock for all streams

[Imre Deak <imre.deak@intel.com>]

On Tue, Sep 04, 2018 at 03:08:16PM +0300, Jani Nikula wrote:
> On Fri, 31 Aug 2018, Imre Deak <imre.deak@intel.com> wrote:
> > commit afb2c4437dae ("drm/i915/ddi: Push pipe clock enabling to encoders")
> > inadvertently stopped enabling the pipe clock for any DP-MST stream
> > after the first one. It also rearranged the pipe clock enabling wrt.
> > initial MST payload allocation step (which may or may not be a
> > problem, but it's contrary to the spec.).
> >
> > Fix things by making the above commit truly a non-functional change.
> 
> What kind of MST setups do we have in CI? Why didn't they catch this?

What we'd need is a dock/other branch device with an DP-MST input and
two outputs. That would exercise the case that broke here.

> 
> BR,
> Jani.
> 
> 
> 
> >
> > Fixes: commit afb2c4437dae ("drm/i915/ddi: Push pipe clock enabling to encoders")
> > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=107365
> > Reported-by: Lyude Paul <lyude@redhat.com>
> > Reported-by: dmummenschanz@web.de
> > Tested-by: dmummenschanz@web.de
> > Cc: Lyude Paul <lyude@redhat.com>
> > Cc: dmummenschanz@web.de
> > Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
> > Cc: Chris Wilson <chris@chris-wilson.co.uk>
> > Signed-off-by: Imre Deak <imre.deak@intel.com>
> > ---
> >  drivers/gpu/drm/i915/intel_ddi.c    | 17 +++++++++--------
> >  drivers/gpu/drm/i915/intel_dp_mst.c |  4 ++++
> >  2 files changed, 13 insertions(+), 8 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
> > index f3b115ce4029..dcb1a98d624d 100644
> > --- a/drivers/gpu/drm/i915/intel_ddi.c
> > +++ b/drivers/gpu/drm/i915/intel_ddi.c
> > @@ -2912,7 +2912,8 @@ static void intel_ddi_pre_enable_dp(struct intel_encoder *encoder,
> >  
> >  	icl_enable_phy_clock_gating(dig_port);
> >  
> > -	intel_ddi_enable_pipe_clock(crtc_state);
> > +	if (!is_mst)
> > +		intel_ddi_enable_pipe_clock(crtc_state);
> >  }
> >  
> >  static void intel_ddi_pre_enable_hdmi(struct intel_encoder *encoder,
> > @@ -3015,14 +3016,14 @@ static void intel_ddi_post_disable_dp(struct intel_encoder *encoder,
> >  	bool is_mst = intel_crtc_has_type(old_crtc_state,
> >  					  INTEL_OUTPUT_DP_MST);
> >  
> > -	intel_ddi_disable_pipe_clock(old_crtc_state);
> > -
> > -	/*
> > -	 * Power down sink before disabling the port, otherwise we end
> > -	 * up getting interrupts from the sink on detecting link loss.
> > -	 */
> > -	if (!is_mst)
> > +	if (!is_mst) {
> > +		intel_ddi_disable_pipe_clock(old_crtc_state);
> > +		/*
> > +		 * Power down sink before disabling the port, otherwise we end
> > +		 * up getting interrupts from the sink on detecting link loss.
> > +		 */
> >  		intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_OFF);
> > +	}
> >  
> >  	intel_disable_ddi_buf(encoder);
> >  
> > diff --git a/drivers/gpu/drm/i915/intel_dp_mst.c b/drivers/gpu/drm/i915/intel_dp_mst.c
> > index 352e5216cc65..77920f1a3da1 100644
> > --- a/drivers/gpu/drm/i915/intel_dp_mst.c
> > +++ b/drivers/gpu/drm/i915/intel_dp_mst.c
> > @@ -166,6 +166,8 @@ static void intel_mst_post_disable_dp(struct intel_encoder *encoder,
> >  	struct intel_connector *connector =
> >  		to_intel_connector(old_conn_state->connector);
> >  
> > +	intel_ddi_disable_pipe_clock(old_crtc_state);
> > +
> >  	/* this can fail */
> >  	drm_dp_check_act_status(&intel_dp->mst_mgr);
> >  	/* and this can also fail */
> > @@ -249,6 +251,8 @@ static void intel_mst_pre_enable_dp(struct intel_encoder *encoder,
> >  	I915_WRITE(DP_TP_STATUS(port), temp);
> >  
> >  	ret = drm_dp_update_payload_part1(&intel_dp->mst_mgr);
> > +
> > +	intel_ddi_enable_pipe_clock(pipe_config);
> >  }
> >  
> >  static void intel_mst_enable_dp(struct intel_encoder *encoder,
> 
> -- 
> Jani Nikula, Intel Open Source Graphics Center
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