[Intel-gfx] [PATCH v4 4/6] drm/i915/dp: Fix MST disable sequences

Souza, Jose jose.souza at intel.com
Wed Dec 18 21:25:33 UTC 2019


On Wed, 2019-12-18 at 22:08 +0200, Ville Syrjälä wrote:
> On Wed, Dec 18, 2019 at 10:59:08AM -0800, José Roberto de Souza
> wrote:
> > The disable sequence after wait for transcoder off was not
> > correctly
> > implemented.
> > The MST disable sequence is basically the same for HSW, SKL, ICL
> > and
> > TGL, with just minor changes for TGL.
> > 
> > With this last patch we finally fixed the hotplugs triggered by MST
> > sinks during the disable/enable sequence, those were causing source
> > to try to do a link training while it was not ready causing CPU
> > pipe
> > FIFO underrrus on TGL.
> > 
> > v2: Only unsetting TGL_TRANS_DDI_PORT_MASK for TGL on the post
> > disable sequence
> > 
> > v4: Rebased, moved MST sequences to intel_mst_post_disable_dp()
> > 
> > BSpec: 4231
> > BSpec: 4163
> > BSpec: 22243
> > BSpec: 49190
> > Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
> > Cc: Lucas De Marchi <lucas.demarchi at intel.com>
> > Signed-off-by: José Roberto de Souza <jose.souza at intel.com>
> > ---
> >  drivers/gpu/drm/i915/display/intel_ddi.c    | 33 +++++++++++++++
> > ------
> >  drivers/gpu/drm/i915/display/intel_dp_mst.c | 33 +++++++++++++--
> > ------
> >  2 files changed, 44 insertions(+), 22 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/display/intel_ddi.c
> > b/drivers/gpu/drm/i915/display/intel_ddi.c
> > index 9d99ec82d072..94ca26be2fee 100644
> > --- a/drivers/gpu/drm/i915/display/intel_ddi.c
> > +++ b/drivers/gpu/drm/i915/display/intel_ddi.c
> > @@ -34,6 +34,7 @@
> >  #include "intel_ddi.h"
> >  #include "intel_display_types.h"
> >  #include "intel_dp.h"
> > +#include "intel_dp_mst.h"
> >  #include "intel_dp_link_training.h"
> >  #include "intel_dpio_phy.h"
> >  #include "intel_dsi.h"
> > @@ -1949,17 +1950,19 @@ void
> > intel_ddi_disable_transcoder_func(const struct intel_crtc_state
> > *crtc_state
> >  	struct intel_crtc *crtc = to_intel_crtc(crtc_state->uapi.crtc);
> >  	struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);
> >  	enum transcoder cpu_transcoder = crtc_state->cpu_transcoder;
> > -	i915_reg_t reg = TRANS_DDI_FUNC_CTL(cpu_transcoder);
> > -	u32 val = I915_READ(reg);
> > +	u32 val;
> > +
> > +	val = I915_READ(TRANS_DDI_FUNC_CTL(cpu_transcoder));
> > +	val &= ~TRANS_DDI_FUNC_ENABLE;
> >  
> >  	if (INTEL_GEN(dev_priv) >= 12) {
> > -		val &= ~(TRANS_DDI_FUNC_ENABLE |
> > TGL_TRANS_DDI_PORT_MASK |
> > -			 TRANS_DDI_DP_VC_PAYLOAD_ALLOC);
> > +		if (!intel_crtc_has_type(crtc_state,
> > INTEL_OUTPUT_DP_MST) ||
> > +		    intel_dp_mst_is_slave_trans(crtc_state))
> 
> if (!intel_dp_mst_is_master_trans())
> 	val &= ...;

Makes cleaner, thanks

> 
> ?
> 
> > +			val &= ~TGL_TRANS_DDI_PORT_MASK;
> >  	} else {
> > -		val &= ~(TRANS_DDI_FUNC_ENABLE | TRANS_DDI_PORT_MASK |
> > -			 TRANS_DDI_DP_VC_PAYLOAD_ALLOC);
> > +		val &= ~TRANS_DDI_PORT_MASK;
> >  	}
> > -	I915_WRITE(reg, val);
> > +	I915_WRITE(TRANS_DDI_FUNC_CTL(cpu_transcoder), val);
> >  
> >  	if (dev_priv->quirks & QUIRK_INCREASE_DDI_DISABLED_TIME &&
> >  	    intel_crtc_has_type(crtc_state, INTEL_OUTPUT_HDMI)) {
> > @@ -3808,8 +3811,20 @@ static void intel_ddi_post_disable_dp(struct
> > intel_encoder *encoder,
> >  	 */
> >  	intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_OFF);
> >  
> > -	if (INTEL_GEN(dev_priv) < 12 && !is_mst)
> > -		intel_ddi_disable_pipe_clock(old_crtc_state);
> > +	if (INTEL_GEN(dev_priv) >= 12) {
> > +		if (is_mst) {
> 
> if (intel_dp_mst_is_master_trans()) {

If you are talking about replace "if (is_mst)" by "if
(intel_dp_mst_is_master_trans())" both are the same as this function
will only be called for master. But if you are thinking in replace "if
(INTEL_GEN(dev_priv) >= 12)" too it will not work.

Will keep is_mst as we already have it the stack of this functions and
is shorter

> 
> ?
> 
> > +			enum transcoder cpu_transcoder;
> > +			u32 val;
> > +
> > +			cpu_transcoder = old_crtc_state-
> > >cpu_transcoder;
> 
> Assignment can be done when declaring the variable.

Okay it is less than 100col.

> 
> > +			val =
> > I915_READ(TRANS_DDI_FUNC_CTL(cpu_transcoder));
> > +			val &= ~TGL_TRANS_DDI_PORT_MASK;
> > +			I915_WRITE(TRANS_DDI_FUNC_CTL(cpu_transcoder),
> > val);
> > +		}
> > +	} else {
> > +		if (!is_mst)
> > +			intel_ddi_disable_pipe_clock(old_crtc_state);
> > +	}
> >  
> >  	intel_disable_ddi_buf(encoder, old_crtc_state);
> >  
> > diff --git a/drivers/gpu/drm/i915/display/intel_dp_mst.c
> > b/drivers/gpu/drm/i915/display/intel_dp_mst.c
> > index 710137984c71..efd14b0b507b 100644
> > --- a/drivers/gpu/drm/i915/display/intel_dp_mst.c
> > +++ b/drivers/gpu/drm/i915/display/intel_dp_mst.c
> > @@ -347,6 +347,7 @@ static void intel_mst_post_disable_dp(struct
> > intel_encoder *encoder,
> >  		to_intel_connector(old_conn_state->connector);
> >  	struct drm_i915_private *dev_priv = to_i915(connector-
> > >base.dev);
> >  	bool last_mst_stream;
> > +	u32 val;
> >  
> >  	intel_dp->active_mst_links--;
> >  	last_mst_stream = intel_dp->active_mst_links == 0;
> > @@ -357,6 +358,19 @@ static void intel_mst_post_disable_dp(struct
> > intel_encoder *encoder,
> >  
> >  	intel_disable_pipe(old_crtc_state);
> >  
> > +	drm_dp_update_payload_part2(&intel_dp->mst_mgr);
> 
> Hmm. I'm having hard to figuring out what these things do. But from a
> cursory glance it almost looks like part1 is the one that does the
> AUX
> stuff to deallocate stuff. So feels like even that part should be
> here.

part2 also do aux stuff.
I also did not deep dive into this part but other drivers also split
part1 and part2. 

> 
> > +
> > +	val = I915_READ(TRANS_DDI_FUNC_CTL(old_crtc_state-
> > >cpu_transcoder));
> > +	val &= ~TRANS_DDI_DP_VC_PAYLOAD_ALLOC;
> > +	I915_WRITE(TRANS_DDI_FUNC_CTL(old_crtc_state->cpu_transcoder),
> > val);
> > +
> > +	if (intel_de_wait_for_set(dev_priv, intel_dp-
> > >regs.dp_tp_status,
> > +				  DP_TP_STATUS_ACT_SENT, 1))
> > +		DRM_ERROR("Timed out waiting for ACT sent when
> > disabling\n");
> 
> I guess we were missing this step entirely. Dunno if we want ERROR
> for
> this. Not sure how much noise it'll generate when someone forcefully
> yanks the cable...

This waits the HW send the ACT, it do not wait for any sink
confirmation. We dont get any warning when removing the cable.

> 
> > +	drm_dp_check_act_status(&intel_dp->mst_mgr);
> > +
> > +	drm_dp_mst_deallocate_vcpi(&intel_dp->mst_mgr, connector-
> > >port);
> 
> This seems to be pure sw stuff so not so critical where it is.
> Keeping
> it next to the hw payload deallocation seems like a good approach.
> 
> > +
> >  	intel_ddi_disable_transcoder_func(old_crtc_state);
> >  
> >  	if (INTEL_GEN(dev_priv) >= 9)
> > @@ -364,6 +378,12 @@ static void intel_mst_post_disable_dp(struct
> > intel_encoder *encoder,
> >  	else
> >  		ironlake_pfit_disable(old_crtc_state);
> >  
> > +	/*
> > +	 * Power down mst path before disabling the port, otherwise we
> > end
> > +	 * up getting interrupts from the sink upon detecting link
> > loss.
> > +	 */
> > +	drm_dp_send_power_updown_phy(&intel_dp->mst_mgr, connector-
> > >port,
> > +				     false);
> 
> And I guess this was needed to avoid the link loss screams from the
> sink?

Yes, we were doing it too late and sink was not happy.

> 
> Seems to match the spec better than before at least. Still a bit
> unsure
> about he part1/2 stuff for the deallocation. But if that should be
> changed we can do it as a followup.

Sure

> 
> The code movement into .post_disable() really did make for a much
> nicer experience when comparing with the spec. Or at least I didn't
> lose as much hair as with the previous version :)

Thanks for that, I had imagined a way bigger change when you suggested
it.

> 
> Reviewed-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
> 
> >  	/*
> >  	 * From TGL spec: "If multi-stream slave transcoder: Configure
> >  	 * Transcoder Clock Select to direct no clock to the
> > transcoder"
> > @@ -374,19 +394,6 @@ static void intel_mst_post_disable_dp(struct
> > intel_encoder *encoder,
> >  	if (INTEL_GEN(dev_priv) < 12 || !last_mst_stream)
> >  		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 */
> > -	drm_dp_update_payload_part2(&intel_dp->mst_mgr);
> > -
> > -	drm_dp_mst_deallocate_vcpi(&intel_dp->mst_mgr, connector-
> > >port);
> > -
> > -	/*
> > -	 * Power down mst path before disabling the port, otherwise we
> > end
> > -	 * up getting interrupts from the sink upon detecting link
> > loss.
> > -	 */
> > -	drm_dp_send_power_updown_phy(&intel_dp->mst_mgr, connector-
> > >port,
> > -				     false);
> >  
> >  	intel_mst->connector = NULL;
> >  	if (last_mst_stream)
> > -- 
> > 2.24.1


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