Re: [Intel-gfx] [PATCH v2 1/6] drm/i915/tgl+: Use the correct DP_TP_* register instances in MST encoders

["Souza, Jose" <jose.souza@intel.com>]

On Wed, 2020-06-17 at 00:11 +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 an MST encoder
> connected to a slave transcoder we reset these register addresses in
> intel_dp::regs.dp_tp_* to the slave transcoder's DP_TP_* register
> addresses incorrectly; fix this.
> 
> One example where the above overwite happens is the encoder HW state
> validation after enabling multiple streams; see
> intel_dp_mst_enc_get_config(). After that during disabling any stream
> we'll get a
> 
> 'Timed out waiting for ACT sent when disabling'
> 
> error, due to reading from the incorrect DP_TP_STATUS register.
> 
> This change replaces
> https://patchwork.freedesktop.org/patch/369577/?series=78193&rev=1
> which just papered over the problem.
> 
> v2:
> - Correct the failure scenario in the commit log. (José)
> 

Reviewed-by: José Roberto de Souza <jose.souza@intel.com>

> 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>
> Reviewed-by: Ville Syrjälä <ville.syrjala@linux.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);
> +	}
> +
>  	pipe_config->has_audio =
>  		intel_ddi_is_audio_enabled(dev_priv, cpu_transcoder);
>  
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