Re: [Intel-gfx] [PATCH 1/6] drm/i915/tgl+: Use the correct DP_TP_* register instances in MST encoders

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

On Tue, Jun 16, 2020 at 07:32:46PM +0300, Souza, Jose wrote:
> On Tue, 2020-06-16 at 17:18 +0300, Imre Deak wrote:
> > MST encoders must use the master MST transcoder's DP_TP_STATUS and
> > DP_TP_CONTROL registers. Atm, during the HW readout of a slave
> > transcoder's CRTC state we reset these register addresses in
> > intel_dp::regs.dp_tp_* to the slave transcoder's DP_TP_* register
> > addresses incorrectly; fix this.
> > 
> > This issue led at least to
> > 'Timed out waiting for ACT sent when disabling'
> > errors during output disabling in a multiple MST stream config.
> 
> Can you point to place where dp_tp_ctl is used and cause this?  All
> the MST code paths uses the dp_tp_ctl of the main intel_dp(the one
> that is not a mst connector).

During a slave stream disabling when waiting for the ACT sent flag for
that stream.

> 
> > 
> > This change replaces
> > https://patchwork.freedesktop.org/patch/369577/?series=78193&rev=1
> > which just papered over the problem.
> > 
> > Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > Cc: José Roberto de Souza <jose.souza@intel.com>
> > Signed-off-by: Imre Deak <imre.deak@intel.com>
> > ---
> >  drivers/gpu/drm/i915/display/intel_ddi.c | 15 ++++++++++-----
> >  1 file changed, 10 insertions(+), 5 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/display/intel_ddi.c b/drivers/gpu/drm/i915/display/intel_ddi.c
> > index ca7bb2294d2b..73d6cc29291a 100644
> > --- a/drivers/gpu/drm/i915/display/intel_ddi.c
> > +++ b/drivers/gpu/drm/i915/display/intel_ddi.c
> > @@ -4193,11 +4193,6 @@ void intel_ddi_get_config(struct intel_encoder *encoder,
> >  	if (drm_WARN_ON(&dev_priv->drm, transcoder_is_dsi(cpu_transcoder)))
> >  		return;
> >  
> > -	if (INTEL_GEN(dev_priv) >= 12) {
> > -		intel_dp->regs.dp_tp_ctl = TGL_DP_TP_CTL(cpu_transcoder);
> > -		intel_dp->regs.dp_tp_status = TGL_DP_TP_STATUS(cpu_transcoder);
> > -	}
> > -
> >  	intel_dsc_get_config(encoder, pipe_config);
> >  
> >  	temp = intel_de_read(dev_priv, TRANS_DDI_FUNC_CTL(cpu_transcoder));
> > @@ -4299,6 +4294,16 @@ void intel_ddi_get_config(struct intel_encoder *encoder,
> >  		break;
> >  	}
> >  
> > +	if (INTEL_GEN(dev_priv) >= 12) {
> > +		enum transcoder transcoder =
> > +			intel_dp_mst_is_slave_trans(pipe_config) ?
> > +			pipe_config->mst_master_transcoder :
> > +			pipe_config->cpu_transcoder;
> > +
> > +		intel_dp->regs.dp_tp_ctl = TGL_DP_TP_CTL(transcoder);
> > +		intel_dp->regs.dp_tp_status = TGL_DP_TP_STATUS(transcoder);
> > +	}
> 
> Also not sure how change only in the config readout would fix the issue, 

After a modeset we'll verify the HW state. The readout for a slave
stream CRTC (get_pipe_config) running after the master CRTC's readout
will overwrite the dp_tp reg addresses. The other instance of dp_tp
register address init (in tgl_ddi_pre_enable_dp()) is correct.

> IFWI don't enable MST so when i915 takes over a full modeset will
> happen to enable MST and only dp_tp_ctl of the main intel_dp(the one
> that is not a mst connector) will be set, check
> tgl_ddi_pre_enable_dp().
> 
> > +
> >  	pipe_config->has_audio =
> >  		intel_ddi_is_audio_enabled(dev_priv, cpu_transcoder);
> >  
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