Re: [PATCH 3/6] drm/i915: Add support for DRRS to switch RR

[Jani Nikula <jani.nikula@linux.intel.com>]

On Fri, 28 Mar 2014, Vandana Kannan <vandana.kannan@intel.com> wrote:
> From: Pradeep Bhat <pradeep.bhat@intel.com>
>
> This patch computes and stored 2nd M/N/TU for switching to different
> refresh rate dynamically. PIPECONF_EDP_RR_MODE_SWITCH bit helps toggle
> between alternate refresh rates programmed in 2nd M/N/TU registers.
>
> v2: Daniel's review comments
> Computing M2/N2 in compute_config and storing it in crtc_config
>
> v3: Modified reference to edp_downclock and edp_downclock_avail based on the
> changes made to move them from dev_private to intel_panel.
>
> v4: Modified references to is_drrs_supported based on the changes made to
> rename it to drrs_support.
>
> v5: Jani's review comments
> Removed superfluous return statements. Changed support for Gen 7 and above.
> Corrected indentation. Re-structured the code which finds crtc and connector
> from encoder. Changed some logs to be less verbose.
>
> v6: Modifying i915_drrs to include only intel connector as intel_dp can be
> derived from intel connector when required.
>
> v7: As per internal review comments, acquiring mutex just before accessing
> drrs RR. As per Chris's review comments, added documentation about the use
> of locking in the function.
>
> v8: Incorporated Jani's review comments.
> Removed reference to edp_downclock.
>
> Signed-off-by: Pradeep Bhat <pradeep.bhat@intel.com>
> Signed-off-by: Vandana Kannan <vandana.kannan@intel.com>
> Cc: Jani Nikula <jani.nikula@linux.intel.com>
> ---
>  drivers/gpu/drm/i915/i915_drv.h  |    5 ++
>  drivers/gpu/drm/i915/i915_reg.h  |    1 +
>  drivers/gpu/drm/i915/intel_dp.c  |  108 ++++++++++++++++++++++++++++++++++++++
>  drivers/gpu/drm/i915/intel_drv.h |    6 ++-
>  4 files changed, 119 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index cd73a33..1c9d5cf 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -794,6 +794,10 @@ struct i915_fbc {
>  	} no_fbc_reason;
>  };
>  
> +struct i915_drrs {
> +	struct intel_connector *connector;
> +};
> +
>  struct i915_psr {
>  	bool sink_support;
>  	bool source_ok;
> @@ -1497,6 +1501,7 @@ typedef struct drm_i915_private {
>  	struct timer_list hotplug_reenable_timer;
>  
>  	struct i915_fbc fbc;
> +	struct i915_drrs drrs;
>  	struct intel_opregion opregion;
>  	struct intel_vbt_data vbt;
>  
> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> index 74f7d85..04fc64a 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -3255,6 +3255,7 @@ enum punit_power_well {
>  #define   PIPECONF_INTERLACED_DBL_ILK		(4 << 21) /* ilk/snb only */
>  #define   PIPECONF_PFIT_PF_INTERLACED_DBL_ILK	(5 << 21) /* ilk/snb only */
>  #define   PIPECONF_INTERLACE_MODE_MASK		(7 << 21)
> +#define   PIPECONF_EDP_RR_MODE_SWITCH		(1 << 20)
>  #define   PIPECONF_CXSR_DOWNCLOCK	(1<<16)
>  #define   PIPECONF_COLOR_RANGE_SELECT	(1 << 13)
>  #define   PIPECONF_BPC_MASK	(0x7 << 5)
> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> index f2735de..9640df1 100644
> --- a/drivers/gpu/drm/i915/intel_dp.c
> +++ b/drivers/gpu/drm/i915/intel_dp.c
> @@ -736,6 +736,20 @@ intel_dp_set_clock(struct intel_encoder *encoder,
>  	}
>  }
>  
> +static void
> +intel_dp_set_m2_n2(struct intel_crtc *crtc, struct intel_link_m_n *m_n)
> +{
> +	struct drm_device *dev = crtc->base.dev;
> +	struct drm_i915_private *dev_priv = dev->dev_private;
> +	enum transcoder transcoder = crtc->config.cpu_transcoder;
> +
> +	I915_WRITE(PIPE_DATA_M2(transcoder),
> +		TU_SIZE(m_n->tu) | m_n->gmch_m);
> +	I915_WRITE(PIPE_DATA_N2(transcoder), m_n->gmch_n);
> +	I915_WRITE(PIPE_LINK_M2(transcoder), m_n->link_m);
> +	I915_WRITE(PIPE_LINK_N2(transcoder), m_n->link_n);
> +}
> +
>  bool
>  intel_dp_compute_config(struct intel_encoder *encoder,
>  			struct intel_crtc_config *pipe_config)
> @@ -840,6 +854,15 @@ found:
>  			       pipe_config->port_clock,
>  			       &pipe_config->dp_m_n);
>  
> +	if (intel_connector->panel.downclock_mode != NULL &&
> +		intel_dp->drrs_state.type == SEAMLESS_DRRS_SUPPORT) {
> +			intel_link_compute_m_n(bpp, lane_count,
> +				intel_connector->panel.downclock_mode->clock,
> +				pipe_config->port_clock,
> +				&pipe_config->dp_m2_n2);
> +	}
> +
> +
>  	intel_dp_set_clock(encoder, pipe_config, intel_dp->link_bw);
>  
>  	return true;
> @@ -3611,6 +3634,87 @@ intel_dp_init_panel_power_sequencer_registers(struct drm_device *dev,
>  		      I915_READ(pp_div_reg));
>  }
>  
> +void intel_dp_set_drrs_state(struct drm_device *dev, int refresh_rate)
> +{
> +	struct drm_i915_private *dev_priv = dev->dev_private;
> +	struct intel_encoder *encoder;
> +	struct intel_dp *intel_dp = NULL;
> +	struct intel_crtc_config *config = NULL;
> +	struct intel_crtc *intel_crtc = NULL;
> +	struct intel_connector *intel_connector = dev_priv->drrs.connector;
> +	u32 reg, val;
> +	int index = 0;

enum edp_drrs_refresh_rate.

> +
> +	if (refresh_rate <= 0) {
> +		DRM_DEBUG_KMS("Refresh rate should be positive non-zero.\n");
> +		return;
> +	}
> +
> +	if (intel_connector == NULL) {
> +		DRM_DEBUG_KMS("DRRS supported for eDP only.\n");
> +		return;
> +	}
> +
> +	encoder = intel_attached_encoder(&intel_connector->base);
> +	intel_dp = enc_to_intel_dp(&encoder->base);
> +	intel_crtc = encoder->new_crtc;
> +
> +	if (!intel_crtc) {
> +		DRM_DEBUG_KMS("DRRS: intel_crtc not initialized\n");
> +		return;
> +	}
> +
> +	config = &intel_crtc->config;
> +
> +	if (intel_dp->drrs_state.type < SEAMLESS_DRRS_SUPPORT) {
> +		DRM_DEBUG_KMS("Seamless DRRS not supported.\n");

Isn't seamless the only thing that *is* supported?

> +		return;
> +	}
> +
> +	if (intel_connector->panel.fixed_mode->vrefresh == refresh_rate)
> +		index = DRRS_HIGH_RR;
> +	else
> +		index = DRRS_LOW_RR;
> +
> +	if (index == intel_dp->drrs_state.refresh_rate_type) {
> +		DRM_DEBUG_KMS(
> +			"DRRS requested for previously set RR...ignoring\n");
> +		return;
> +	}
> +
> +	if (!intel_crtc->active) {
> +		DRM_DEBUG_KMS("eDP encoder disabled. CRTC not Active\n");
> +		return;
> +	}
> +
> +	if (INTEL_INFO(dev)->gen > 6 && INTEL_INFO(dev)->gen < 8) {

Can we end up here when drrs is not supported by the platform?

> +		reg = PIPECONF(intel_crtc->config.cpu_transcoder);
> +		val = I915_READ(reg);
> +		if (index > DRRS_HIGH_RR) {
> +			val |= PIPECONF_EDP_RR_MODE_SWITCH;
> +			intel_dp_set_m2_n2(intel_crtc, &config->dp_m2_n2);
> +		} else {
> +			val &= ~PIPECONF_EDP_RR_MODE_SWITCH;
> +		}
> +		I915_WRITE(reg, val);
> +	}
> +
> +	/*
> +	 * mutex taken to ensure that there is no race between differnt
> +	 * drrs calls trying to update refresh rate. This scenario may occur
> +	 * in future when idleness detection based DRRS in kernel and
> +	 * possible calls from user space to set differnt RR are made.
> +	 */
> +
> +	mutex_lock(&intel_dp->drrs_state.mutex);
> +
> +	intel_dp->drrs_state.refresh_rate_type = index;
> +
> +	mutex_unlock(&intel_dp->drrs_state.mutex);
> +
> +	DRM_DEBUG_KMS("eDP Refresh Rate set to : %dHz\n", refresh_rate);
> +}
> +
>  static struct drm_display_mode *
>  intel_dp_drrs_init(struct intel_digital_port *intel_dig_port,
>  			struct intel_connector *intel_connector,
> @@ -3647,6 +3751,10 @@ intel_dp_drrs_init(struct intel_digital_port *intel_dig_port,
>  
>  	if (downclock_mode != NULL &&
>  		dev_priv->vbt.drrs_type == SEAMLESS_DRRS_SUPPORT) {
> +		dev_priv->drrs.connector = intel_connector;
> +
> +		mutex_init(&intel_dp->drrs_state.mutex);
> +
>  		intel_dp->drrs_state.type = dev_priv->vbt.drrs_type;
>  
>  		intel_dp->drrs_state.refresh_rate_type = DRRS_HIGH_RR;
> diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
> index d781165..46fc8b3 100644
> --- a/drivers/gpu/drm/i915/intel_drv.h
> +++ b/drivers/gpu/drm/i915/intel_drv.h
> @@ -305,6 +305,9 @@ struct intel_crtc_config {
>  	int pipe_bpp;
>  	struct intel_link_m_n dp_m_n;
>  
> +	/* m2_n2 for eDP downclock */
> +	struct intel_link_m_n dp_m2_n2;
> +
>  	/*
>  	 * Frequence the dpll for the port should run at. Differs from the
>  	 * adjusted dotclock e.g. for DP or 12bpc hdmi mode. This is also
> @@ -535,6 +538,7 @@ struct intel_dp {
>  	struct {
>  		enum drrs_support_type type;
>  		enum edp_drrs_refresh_rate_type refresh_rate_type;
> +		struct mutex mutex;
>  	} drrs_state;
>  
>  };
> @@ -789,7 +793,7 @@ void intel_edp_panel_off(struct intel_dp *intel_dp);
>  void intel_edp_psr_enable(struct intel_dp *intel_dp);
>  void intel_edp_psr_disable(struct intel_dp *intel_dp);
>  void intel_edp_psr_update(struct drm_device *dev);
> -
> +void intel_dp_set_drrs_state(struct drm_device *dev, int refresh_rate);
>  
>  /* intel_dsi.c */
>  bool intel_dsi_init(struct drm_device *dev);
> -- 
> 1.7.9.5
>

-- 
Jani Nikula, Intel Open Source Technology Center