Re: [PATCH 3/5] drm/i915/tgl: do not enable transcoder clock twice on MST

From: "Souza, Jose" <jose.souza@intel.com>
To: "intel-gfx@lists.freedesktop.org"
	<intel-gfx@lists.freedesktop.org>,
	"De Marchi, Lucas" <lucas.demarchi@intel.com>
Subject: Re: [PATCH 3/5] drm/i915/tgl: do not enable transcoder clock twice on MST
Date: Fri, 1 Nov 2019 00:37:39 +0000	[thread overview]
Message-ID: <c4090752c7b497b0dec0c815216c6ef35de9f057.camel@intel.com> (raw)
In-Reply-To: <20191030012448.14937-4-lucas.demarchi@intel.com>

On Tue, 2019-10-29 at 18:24 -0700, Lucas De Marchi wrote:
> For MST on Tiger Lake there are different moments when we need to
> configure the transcoder clock select. For the first link this is in
> step
> 7.a of the spec, before training the link.  For additional streams
> this
> should be done as part of step 8.b after programming receiver VC
> Payload
> ID.
> 
> Bspec: 49190
> 

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

> Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_ddi.c    |  7 ++++---
>  drivers/gpu/drm/i915/display/intel_dp_mst.c | 16 +++++++++++++---
>  2 files changed, 17 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_ddi.c
> b/drivers/gpu/drm/i915/display/intel_ddi.c
> index fed7fc56dd92..2ce998529d08 100644
> --- a/drivers/gpu/drm/i915/display/intel_ddi.c
> +++ b/drivers/gpu/drm/i915/display/intel_ddi.c
> @@ -3462,9 +3462,10 @@ static void tgl_ddi_pre_enable_dp(struct
> intel_encoder *encoder,
>  	icl_program_mg_dp_mode(dig_port, crtc_state);
>  
>  	/*
> -	 * 7.a - Steps in this function should only be executed over
> MST
> -	 * master, what will be taken in care by MST hook
> -	 * intel_mst_pre_enable_dp()
> +	 * 7.a - single stream or multi-stream master transcoder:
> Configure
> +	 * Transcoder Clock Select. For additional MST streams this
> will be done
> +	 * by intel_mst_pre_enable_dp() after programming VC Payload ID
> through
> +	 * AUX.
>  	 */
>  	intel_ddi_enable_pipe_clock(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 a9962846a503..ad54618f6142 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp_mst.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp_mst.c
> @@ -299,21 +299,23 @@ static void intel_mst_pre_enable_dp(struct
> intel_encoder *encoder,
>  		to_intel_connector(conn_state->connector);
>  	int ret;
>  	u32 temp;
> +	bool first_mst_stream;
>  
>  	/* MST encoders are bound to a crtc, not to a connector,
>  	 * force the mapping here for get_hw_state.
>  	 */
>  	connector->encoder = encoder;
>  	intel_mst->connector = connector;
> +	first_mst_stream = intel_dp->active_mst_links == 0;
>  
>  	DRM_DEBUG_KMS("active links %d\n", intel_dp->active_mst_links);
>  
> -	if (intel_dp->active_mst_links == 0)
> +	if (first_mst_stream)
>  		intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_ON);
>  
>  	drm_dp_send_power_updown_phy(&intel_dp->mst_mgr, connector-
> >port, true);
>  
> -	if (intel_dp->active_mst_links == 0)
> +	if (first_mst_stream)
>  		intel_dig_port->base.pre_enable(&intel_dig_port->base,
>  						pipe_config, NULL);
>  
> @@ -330,7 +332,15 @@ static void intel_mst_pre_enable_dp(struct
> intel_encoder *encoder,
>  
>  	ret = drm_dp_update_payload_part1(&intel_dp->mst_mgr);
>  
> -	intel_ddi_enable_pipe_clock(pipe_config);
> +	/*
> +	 * Before Gen 12 this is not done as part of
> +	 * intel_dig_port->base.pre_enable() and should be done here.
> For
> +	 * Gen 12+ the step in which this should be done is different
> for the
> +	 * first MST stream, so it's done on the DDI for the first
> stream and
> +	 * here for the following ones.
> +	 */
> +	if (INTEL_GEN(dev_priv) < 12 || !first_mst_stream)
> +		intel_ddi_enable_pipe_clock(pipe_config);
>  }
>  
>  static void intel_mst_enable_dp(struct intel_encoder *encoder,
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