On Fri, 2017-05-26 at 18:42 -0700, Puthikorn Voravootivat wrote:
> This patch adds option to enable dynamic backlight 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 <put...@chromium.org>
> ---
> drivers/gpu/drm/i915/i915_params.c | 5 ++++
> drivers/gpu/drm/i915/i915_params.h | 3 +-
> drivers/gpu/drm/i915/intel_dp_aux_backlight.c | 42
> ++++++++++++++++++++++-----
> 3 files changed, 41 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_params.c
> b/drivers/gpu/drm/i915/i915_params.c
> index 3758ae1f11b4..ce033d58134e 100644
> --- a/drivers/gpu/drm/i915/i915_params.c
> +++ b/drivers/gpu/drm/i915/i915_params.c
> @@ -65,6 +65,7 @@ struct i915_params i915 __read_mostly = {
> .inject_load_failure = 0,
> .enable_dpcd_backlight = -1,
> .enable_gvt = false,
> + .enable_dbc = false,
> };
>
> module_param_named(modeset, i915.modeset, int, 0400);
> @@ -254,3 +255,7 @@ MODULE_PARM_DESC(enable_dpcd_backlight,
> module_param_named(enable_gvt, i915.enable_gvt, bool, 0400);
> MODULE_PARM_DESC(enable_gvt,
> "Enable support for Intel GVT-g graphics virtualization host
> support(default:false)");
> +
> +module_param_named_unsafe(enable_dbc, i915.enable_dbc, bool, 0600);
> +MODULE_PARM_DESC(enable_dbc,
> + "Enable support for dynamic backlight control (default:false)");
> diff --git a/drivers/gpu/drm/i915/i915_params.h
> b/drivers/gpu/drm/i915/i915_params.h
> index ac02efce6e22..2de3e2850b54 100644
> --- a/drivers/gpu/drm/i915/i915_params.h
> +++ b/drivers/gpu/drm/i915/i915_params.h
> @@ -67,7 +67,8 @@
> func(bool, nuclear_pageflip); \
> func(bool, enable_dp_mst); \
> func(int, enable_dpcd_backlight); \
> - func(bool, enable_gvt)
> + func(bool, enable_gvt); \
> + func(bool, enable_dbc)
>
> #define MEMBER(T, member) T member
> struct i915_params {
> diff --git a/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
> b/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
> index c89aae804659..f55af41ce3bd 100644
> --- a/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
> +++ b/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
> @@ -100,11 +100,26 @@ 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 edp_backlight_mode = 0;
> + uint8_t dpcd_buf, new_dpcd_buf, edp_backlight_mode;
>
> if (drm_dp_dpcd_readb(&intel_dp->aux,
> DP_EDP_BACKLIGHT_MODE_SET_REGISTER, &dpcd_buf) != 1) {
> @@ -113,18 +128,15 @@ 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 */
> @@ -133,6 +145,20 @@ static void intel_dp_aux_enable_backlight(struct
> intel_connector *connector)
> break;
> }
>
> + if (i915.enable_dbc &&
> + (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");
> + }
> +
Just curious, does DBC require DP AUX brightness control?
-DK
> + 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);
> intel_dp_aux_set_backlight(connector, connector->panel.backlight.level);
> }
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