drm/i915: Add option to support dynamic backlight via DPCD

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 <puthik@chromium.org>
Reviewed-by: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/20170622190339.142671-4-puthik@chromium.org

diff --git a/drivers/gpu/drm/i915/i915_params.c b/drivers/gpu/drm/i915/i915_params.c
index 5b5ab15..88b9d3e 100644 (file)
--- 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 = true,
 };
 
 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:true)");

diff --git a/drivers/gpu/drm/i915/i915_params.h b/drivers/gpu/drm/i915/i915_params.h
index 0d6cf91..057e203 100644 (file)
--- a/drivers/gpu/drm/i915/i915_params.h
+++ b/drivers/gpu/drm/i915/i915_params.h
@@ -67,7 +67,8 @@
        func(bool, verbose_state_checks); \
        func(bool, nuclear_pageflip); \
        func(bool, enable_dp_mst); \
-       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 fea1617..b25cd88 100644 (file)
--- a/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
+++ b/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
@@ -173,6 +173,24 @@ static bool intel_dp_aux_set_pwm_freq(struct intel_connector *connector)
        return true;
 }
 
+/*
+* Set minimum / maximum dynamic brightness percentage. This value is expressed
+* as the percentage of normal brightness in 5% increments.
+*/
+static bool
+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");
+               return false;
+       }
+       return true;
+}
+
 static void intel_dp_aux_enable_backlight(const struct intel_crtc_state *crtc_state,
                                          const struct drm_connector_state *conn_state)
 {
@@ -208,6 +226,14 @@ static void intel_dp_aux_enable_backlight(const struct intel_crtc_state *crtc_st
                if (intel_dp_aux_set_pwm_freq(connector))
                        new_dpcd_buf |= DP_EDP_BACKLIGHT_FREQ_AUX_SET_ENABLE;
 
+       if (i915.enable_dbc &&
+           (intel_dp->edp_dpcd[2] & DP_EDP_DYNAMIC_BACKLIGHT_CAP)) {
+               if(intel_dp_aux_set_dynamic_backlight_percent(intel_dp, 0, 100)) {
+                       new_dpcd_buf |= DP_EDP_DYNAMIC_BACKLIGHT_ENABLE;
+                       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) {