On Wed, 08 Mar 2017, Puthikorn Voravootivat <[email protected]> wrote:
> This patch enables dynamic backlight by default for eDP
> panel that supports this feature via DPCD register and
> set minimum / maximum brightness to 0% and 100% of the
> normal brightness.
>
> Signed-off-by: Puthikorn Voravootivat <[email protected]>
> ---
>  drivers/gpu/drm/i915/intel_dp_aux_backlight.c | 31 
> +++++++++++++++++++++++----
>  1 file changed, 27 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_dp_aux_backlight.c 
> b/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
> index 16cd1265d264..643b604be2de 100644
> --- a/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
> +++ b/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
> @@ -97,10 +97,24 @@ intel_dp_aux_set_backlight(struct intel_connector 
> *connector, u32 level)
>       }
>  }
>  
> +/*
> + * Set minimum / maximum dynamic brightness percentage. This value is 
> expressed
> + * as the percentage of normal brightness in 5% increments.
> + */
> +static void intel_dp_aux_set_dynamic_backlight_percent(
> +             struct intel_dp *intel_dp, u32 min, u32 max)

static void
intel_dp_aux_set_dynamic_backlight_percent(struct intel_dp *intel_dp,
                                           u32 min, u32 max)

would be preferable indentation.

> +{

        u8 dbc[] = { DIV_ROUND_CLOSEST(min, 5), DIV_ROUND_CLOSEST(max, 5)};

        drm_dp_dpcd_write(&intel_dp->aux, DP_EDP_DBC_MINIMUM_BRIGHTNESS_SET,
                          dbc, sizeof(dbc));

> +     drm_dp_dpcd_writeb(&intel_dp->aux,
> +             DP_EDP_DBC_MINIMUM_BRIGHTNESS_SET, min / 5);
> +     drm_dp_dpcd_writeb(&intel_dp->aux,
> +             DP_EDP_DBC_MAXIMUM_BRIGHTNESS_SET, max / 5);
> +}
> +
>  static void intel_dp_aux_enable_backlight(struct intel_connector *connector)
>  {
>       struct intel_dp *intel_dp = enc_to_intel_dp(&connector->encoder->base);
>       uint8_t dpcd_buf = 0;
> +     uint8_t new_dpcd_buf = 0;
>       uint8_t edp_backlight_mode = 0;
>  
>       set_aux_backlight_enable(intel_dp, true);
> @@ -110,15 +124,14 @@ static void intel_dp_aux_enable_backlight(struct 
> intel_connector *connector)
>               return;
>       }
>  
> +     new_dpcd_buf = dpcd_buf;
>       edp_backlight_mode = dpcd_buf & DP_EDP_BACKLIGHT_CONTROL_MODE_MASK;
>  
>       switch (edp_backlight_mode) {
>       case DP_EDP_BACKLIGHT_CONTROL_MODE_PWM:
>       case DP_EDP_BACKLIGHT_CONTROL_MODE_PRESET:
> -             dpcd_buf &= ~DP_EDP_BACKLIGHT_CONTROL_MODE_MASK;
> -             dpcd_buf |= DP_EDP_BACKLIGHT_CONTROL_MODE_DPCD;
> -             drm_dp_dpcd_writeb(&intel_dp->aux,
> -                     DP_EDP_BACKLIGHT_MODE_SET_REGISTER, dpcd_buf);
> +             new_dpcd_buf &= ~DP_EDP_BACKLIGHT_CONTROL_MODE_MASK;
> +             new_dpcd_buf |= DP_EDP_BACKLIGHT_CONTROL_MODE_DPCD;
>               break;
>  
>       /* Do nothing in these cases */
> @@ -127,6 +140,16 @@ static void intel_dp_aux_enable_backlight(struct 
> intel_connector *connector)
>       default:
>               break;
>       }
> +
> +     if (intel_dp->edp_dpcd[2] & DP_EDP_DYNAMIC_BACKLIGHT_CAP) {
> +             new_dpcd_buf |= DP_EDP_DYNAMIC_BACKLIGHT_ENABLE;
> +             intel_dp_aux_set_dynamic_backlight_percent(intel_dp, 0, 100);
> +     }
> +
> +     if (new_dpcd_buf != dpcd_buf) {
> +             drm_dp_dpcd_writeb(&intel_dp->aux,
> +                     DP_EDP_BACKLIGHT_MODE_SET_REGISTER, new_dpcd_buf);
> +     }
>  }
>  
>  static void intel_dp_aux_disable_backlight(struct intel_connector *connector)

-- 
Jani Nikula, Intel Open Source Technology Center
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