Fair enough. Will add kernel switch in next version.
On Wed, May 10, 2017 at 6:26 PM, Pandiyan, Dhinakaran <dhinakaran.pandiyan@xxxxxxxxx> wrote:
On Wed, 2017-05-03 at 17:28 -0700, Puthikorn Voravootivat 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.
I read the link that you shared last time, should there be a switch for
a feature like this that can affect image quality? Should this be a
decision in the kernel with no provision to turn off/on?
-DK
>
> Signed-off-by: Puthikorn Voravootivat <puthik@xxxxxxxxxxxx>
> ---
> drivers/gpu/drm/i915/intel_dp_aux_backlight.c | 39 ++++++++++++++++++++++-----
> 1 file changed, 33 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_dp_aux_backlight.c b/drivers/gpu/drm/i915/intel_ dp_aux_backlight.c
> index 5ef3ade7c40e..7d323af96636 100644
> --- a/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
> +++ b/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
> @@ -97,10 +97,27 @@ 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)
> +{
> + u8 dbc[] = { DIV_ROUND_CLOSEST(min, 5), DIV_ROUND_CLOSEST(max, 5) };
> +
> + if (drm_dp_dpcd_write(&intel_dp->aux, DP_EDP_DBC_MINIMUM_BRIGHTNESS_ SET,
> + dbc, sizeof(dbc) < 0)) {
> + DRM_DEBUG_KMS("Failed to write aux DBC brightness level\n");
> + }
> +}
> +
> 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;
>
> if (drm_dp_dpcd_readb(&intel_dp->aux,
> @@ -110,18 +127,15 @@ 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:
> case DP_EDP_BACKLIGHT_CONTROL_MODE_PRODUCT:
> - dpcd_buf &= ~DP_EDP_BACKLIGHT_CONTROL_MODE_MASK;
> - dpcd_buf |= DP_EDP_BACKLIGHT_CONTROL_MODE_DPCD;
> - if (drm_dp_dpcd_writeb(&intel_dp->aux,
> - DP_EDP_BACKLIGHT_MODE_SET_REGISTER, dpcd_buf) < 0) {
> - DRM_DEBUG_KMS("Failed to write aux backlight mode\n");
> - }
> + new_dpcd_buf &= ~DP_EDP_BACKLIGHT_CONTROL_MODE_MASK;
> + new_dpcd_buf |= DP_EDP_BACKLIGHT_CONTROL_MODE_DPCD;
> break;
>
> /* Do nothing when it is already DPCD mode */
> @@ -130,6 +144,19 @@ static void intel_dp_aux_enable_backlight(struct intel_connector *connector)
> 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);
> + DRM_DEBUG_KMS("Enable dynamic brightness.\n");
> + }
> +
> + if (new_dpcd_buf != dpcd_buf) {
> + if (drm_dp_dpcd_writeb(&intel_dp->aux,
> + DP_EDP_BACKLIGHT_MODE_SET_REGISTER, new_dpcd_buf) < 0) {
> + DRM_DEBUG_KMS("Failed to write aux backlight mode\n");
> + }
> + }
> +
> set_aux_backlight_enable(intel_dp, true);
> }
>
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