Re: [PATCH 3/3] drm/i915/dp: limit DP link rate based on VBT on CNL+

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Thu, Feb 01, 2018 at 01:03:43PM +0200, Jani Nikula wrote:
> We have the max DP link rate info available in VBT since BDB version
> 216, included in child device config since commit c4fb60b9aba9
> ("drm/i915/bios: add DP max link rate to VBT child device
> struct"). Parse it and use it.
> 
> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
> Cc: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
> Signed-off-by: Jani Nikula <jani.nikula@intel.com>
> ---
>  drivers/gpu/drm/i915/i915_drv.h       |  1 +
>  drivers/gpu/drm/i915/intel_bios.c     | 21 +++++++++++++++++++++
>  drivers/gpu/drm/i915/intel_dp.c       |  9 ++++++++-
>  drivers/gpu/drm/i915/intel_vbt_defs.h |  5 +++++
>  4 files changed, 35 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index c676269ed843..26b91c25b8a0 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -1282,6 +1282,7 @@ struct ddi_vbt_port_info {
>  
>  	uint8_t dp_boost_level;
>  	uint8_t hdmi_boost_level;
> +	int dp_max_link_rate;		/* 0 for not limited by VBT */
>  };
>  
>  enum psr_lines_to_wait {
> diff --git a/drivers/gpu/drm/i915/intel_bios.c b/drivers/gpu/drm/i915/intel_bios.c
> index cf3f8f1ba6f7..4e74aa2f16bc 100644
> --- a/drivers/gpu/drm/i915/intel_bios.c
> +++ b/drivers/gpu/drm/i915/intel_bios.c
> @@ -1274,6 +1274,27 @@ static void parse_ddi_port(struct drm_i915_private *dev_priv, enum port port,
>  		DRM_DEBUG_KMS("VBT HDMI boost level for port %c: %d\n",
>  			      port_name(port), info->hdmi_boost_level);
>  	}
> +
> +	/* DP max link rate for CNL+ */
> +	if (bdb_version >= 216) {
> +		switch (child->dp_max_link_rate) {
> +		default:
> +		case VBT_DP_MAX_LINK_RATE_HBR3:
> +			info->dp_max_link_rate = 810000;
> +			break;
> +		case VBT_DP_MAX_LINK_RATE_HBR2:
> +			info->dp_max_link_rate = 540000;
> +			break;
> +		case VBT_DP_MAX_LINK_RATE_HBR:
> +			info->dp_max_link_rate = 270000;
> +			break;
> +		case VBT_DP_MAX_LINK_RATE_LBR:
> +			info->dp_max_link_rate = 162000;
> +			break;
> +		}
> +		DRM_DEBUG_KMS("VBT DP max link rate for port %c: %d\n",
> +			      port_name(port), info->dp_max_link_rate);
> +	}
>  }
>  
>  static void parse_ddi_ports(struct drm_i915_private *dev_priv, u8 bdb_version)
> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> index 8bef858919c8..9a610d4783d8 100644
> --- a/drivers/gpu/drm/i915/intel_dp.c
> +++ b/drivers/gpu/drm/i915/intel_dp.c
> @@ -270,8 +270,10 @@ intel_dp_set_source_rates(struct intel_dp *intel_dp)
>  {
>  	struct intel_digital_port *dig_port = dp_to_dig_port(intel_dp);
>  	struct drm_i915_private *dev_priv = to_i915(dig_port->base.base.dev);
> +	const struct ddi_vbt_port_info *info =
> +		&dev_priv->vbt.ddi_port_info[dig_port->base.port];
>  	const int *source_rates;
> -	int size, max_rate = 0;
> +	int size, max_rate = 0, vbt_max_rate = info->dp_max_link_rate;
>  
>  	/* This should only be done once */
>  	WARN_ON(intel_dp->source_rates || intel_dp->num_source_rates);
> @@ -295,6 +297,11 @@ intel_dp_set_source_rates(struct intel_dp *intel_dp)
>  		size = ARRAY_SIZE(default_rates) - 1;
>  	}
>  
> +	if (max_rate && vbt_max_rate)
> +		max_rate = min(max_rate, vbt_max_rate);
> +	else if (vbt_max_rate)
> +		max_rate = vbt_max_rate;

I kinda wish this would look exactly like the hdmi version, but
can't do that without populating max_rate for every platform. So
I guess we'll go with this.

Series looks good to me:
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

> +
>  	if (max_rate)
>  		size = intel_dp_rate_limit_len(source_rates, size, max_rate);
>  
> diff --git a/drivers/gpu/drm/i915/intel_vbt_defs.h b/drivers/gpu/drm/i915/intel_vbt_defs.h
> index 3d3feee9b5dd..458468237b5f 100644
> --- a/drivers/gpu/drm/i915/intel_vbt_defs.h
> +++ b/drivers/gpu/drm/i915/intel_vbt_defs.h
> @@ -320,6 +320,11 @@ enum vbt_gmbus_ddi {
>  	DDC_BUS_DDI_F,
>  };
>  
> +#define VBT_DP_MAX_LINK_RATE_HBR3	0
> +#define VBT_DP_MAX_LINK_RATE_HBR2	1
> +#define VBT_DP_MAX_LINK_RATE_HBR	2
> +#define VBT_DP_MAX_LINK_RATE_LBR	3
> +
>  /*
>   * The child device config, aka the display device data structure, provides a
>   * description of a port and its configuration on the platform.
> -- 
> 2.11.0

-- 
Ville Syrjälä
Intel OTC
_______________________________________________
Intel-gfx mailing list
Intel-gfx@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/intel-gfx