Re: [PATCH v2] drm/i915/mst: Use MST sideband message transactions for dpms control

[Lyude Paul <lyude@redhat.com>]

Reviewed-by: Lyude Paul <lyude@redhat.com>

On Wed, 2017-09-13 at 13:06 -0700, Dhinakaran Pandiyan wrote:
> Use the POWER_DOWN_PHY and POWER_UP_PHY sideband message transactions to
> set power states for downstream sinks. Apart from giving us the ability
> to set power state for individual sinks, this fixes the below test for
> me.
> 
> $ xrandr --display :0 --output DP-2-2-8 --off
> $ xrandr --display :0 --output DP-2-2-1 --off
> $ xrandr --display :0 --output DP-2-2-8 --auto #Black screen
> $ xrandr --display :0 --output DP-2-2-1 --auto
> 
> v2: Modify and document the dpms and port disable order (Ville)
>     Add comment explaining is_mst = !crtc_state equivalence(Ville, Maarten)
> 
> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> Cc: Lyude <lyude@redhat.com>
> Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> Signed-off-by: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
> ---
>  drivers/gpu/drm/i915/intel_ddi.c    | 18 ++++++++++++++----
>  drivers/gpu/drm/i915/intel_dp_mst.c | 13 +++++++++----
>  2 files changed, 23 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_ddi.c
> b/drivers/gpu/drm/i915/intel_ddi.c
> index 1da3bb2cc4b4..0053d66393f8 100644
> --- a/drivers/gpu/drm/i915/intel_ddi.c
> +++ b/drivers/gpu/drm/i915/intel_ddi.c
> @@ -2161,7 +2161,8 @@ static void intel_ddi_pre_enable_dp(struct
> intel_encoder *encoder,
>  		intel_prepare_dp_ddi_buffers(encoder);
>  
>  	intel_ddi_init_dp_buf_reg(encoder);
> -	intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_ON);
> +	if (!link_mst)
> +		intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_ON);
>  	intel_dp_start_link_train(intel_dp);
>  	if (port != PORT_A || INTEL_GEN(dev_priv) >= 9)
>  		intel_dp_stop_link_train(intel_dp);
> @@ -2235,12 +2236,21 @@ static void intel_ddi_post_disable(struct
> intel_encoder *intel_encoder,
>  	uint32_t val;
>  	bool wait = false;
>  
> -	/* old_crtc_state and old_conn_state are NULL when called from
> DP_MST */
> -
>  	if (type == INTEL_OUTPUT_DP || type == INTEL_OUTPUT_EDP) {
> +		/*
> +		 * old_crtc_state and old_conn_state are NULL when called
> from
> +		 * DP_MST. The main connector associated with this port is
> never
> +		 * bound to a crtc for MST.
> +		 */
> +		bool is_mst = !old_crtc_state;
>  		struct intel_dp *intel_dp = enc_to_intel_dp(encoder);
>  
> -		intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_OFF);
> +		/*
> +		 * Power down sink before disabling the port, otherwise we
> end
> +		 * up getting interrupts from the sink on detecting link
> loss.
> +		 */
> +		if (!is_mst)
> +			intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_OFF);
>  	}
>  
>  	val = I915_READ(DDI_BUF_CTL(port));
> diff --git a/drivers/gpu/drm/i915/intel_dp_mst.c
> b/drivers/gpu/drm/i915/intel_dp_mst.c
> index 8e3aad0ea60b..187f3f05a828 100644
> --- a/drivers/gpu/drm/i915/intel_dp_mst.c
> +++ b/drivers/gpu/drm/i915/intel_dp_mst.c
> @@ -164,15 +164,19 @@ static void intel_mst_post_disable_dp(struct
> intel_encoder *encoder,
>  
>  	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_dp->active_mst_links--;
>  
>  	intel_mst->connector = NULL;
> -	if (intel_dp->active_mst_links == 0) {
> +	if (intel_dp->active_mst_links == 0)
>  		intel_dig_port->base.post_disable(&intel_dig_port->base,
>  						  NULL, NULL);
> -
> -		intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_OFF);
> -	}
>  }
>  
>  static void intel_mst_pre_enable_dp(struct intel_encoder *encoder,
> @@ -197,6 +201,7 @@ static void intel_mst_pre_enable_dp(struct intel_encoder
> *encoder,
>  
>  	DRM_DEBUG_KMS("%d\n", intel_dp->active_mst_links);
>  
> +	drm_dp_send_power_updown_phy(&intel_dp->mst_mgr, connector->port,
> true);
>  	if (intel_dp->active_mst_links == 0)
>  		intel_dig_port->base.pre_enable(&intel_dig_port->base,
>  						pipe_config, NULL);
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