Re: [Intel-gfx] [PATCH] drm/i915/display: Remove check for low voltage sku for max dp source rate

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

On Tue, 05 Oct 2021, Ankit Nautiyal <ankit.k.nautiyal@intel.com> wrote:
> The low voltage sku check can be ignored as OEMs need to consider that
> when designing the board and then put any limits in VBT.

"can" or "must"?

VBT has been notoriously buggy over the years, and we need to safeguard
against that. Are there any cases where having these checks are wrong?

BR,
Jani.

> Same is now changed in Bspec (53720).
>
> Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_dp.c | 32 +++----------------------
>  1 file changed, 3 insertions(+), 29 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
> index 74a657ae131a..75c364c3c88e 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> @@ -297,23 +297,13 @@ static int dg2_max_source_rate(struct intel_dp *intel_dp)
>  	return intel_dp_is_edp(intel_dp) ? 810000 : 1350000;
>  }
>  
> -static bool is_low_voltage_sku(struct drm_i915_private *i915, enum phy phy)
> -{
> -	u32 voltage;
> -
> -	voltage = intel_de_read(i915, ICL_PORT_COMP_DW3(phy)) & VOLTAGE_INFO_MASK;
> -
> -	return voltage == VOLTAGE_INFO_0_85V;
> -}
> -
>  static int icl_max_source_rate(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);
>  	enum phy phy = intel_port_to_phy(dev_priv, dig_port->base.port);
>  
> -	if (intel_phy_is_combo(dev_priv, phy) &&
> -	    (is_low_voltage_sku(dev_priv, phy) || !intel_dp_is_edp(intel_dp)))
> +	if (intel_phy_is_combo(dev_priv, phy) && !intel_dp_is_edp(intel_dp))
>  		return 540000;
>  
>  	return 810000;
> @@ -321,23 +311,7 @@ static int icl_max_source_rate(struct intel_dp *intel_dp)
>  
>  static int ehl_max_source_rate(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);
> -	enum phy phy = intel_port_to_phy(dev_priv, dig_port->base.port);
> -
> -	if (intel_dp_is_edp(intel_dp) || is_low_voltage_sku(dev_priv, phy))
> -		return 540000;
> -
> -	return 810000;
> -}
> -
> -static int dg1_max_source_rate(struct intel_dp *intel_dp)
> -{
> -	struct intel_digital_port *dig_port = dp_to_dig_port(intel_dp);
> -	struct drm_i915_private *i915 = to_i915(dig_port->base.base.dev);
> -	enum phy phy = intel_port_to_phy(i915, dig_port->base.port);
> -
> -	if (intel_phy_is_combo(i915, phy) && is_low_voltage_sku(i915, phy))
> +	if (intel_dp_is_edp(intel_dp))
>  		return 540000;
>  
>  	return 810000;
> @@ -380,7 +354,7 @@ intel_dp_set_source_rates(struct intel_dp *intel_dp)
>  			max_rate = dg2_max_source_rate(intel_dp);
>  		else if (IS_ALDERLAKE_P(dev_priv) || IS_ALDERLAKE_S(dev_priv) ||
>  			 IS_DG1(dev_priv) || IS_ROCKETLAKE(dev_priv))
> -			max_rate = dg1_max_source_rate(intel_dp);
> +			max_rate = 810000;
>  		else if (IS_JSL_EHL(dev_priv))
>  			max_rate = ehl_max_source_rate(intel_dp);
>  		else

-- 
Jani Nikula, Intel Open Source Graphics Center