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

[Souza, Jose]

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).

> 
> This change replaces
> https://patchwork.freedesktop.org/patch/369577/?series=78193&rev=1
> which just papered over the problem.
> 
> Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
> Cc: José Roberto de Souza <jose.souza at intel.com>
> Signed-off-by: Imre Deak <imre.deak at 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, 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);
>