4 files changed, 269 insertions, 31 deletions

diff --git a/drivers/gpu/drm/i915/display/intel_display_types.h b/drivers/gpu/drm/i915/display/intel_display_types.h
index e472127db4a9..d03b030f8797 100644
--- a/drivers/gpu/drm/i915/display/intel_display_types.h
+++ b/drivers/gpu/drm/i915/display/intel_display_types.h
@@ -261,7 +261,14 @@ struct intel_panel {
 		struct pwm_state pwm_state;
 
 		/* DPCD backlight */
-		u8 pwmgen_bit_count;
+		union {
+			struct {
+				u8 pwmgen_bit_count;
+			} vesa;
+			struct {
+				bool sdr_uses_aux;
+			} intel;
+		} edp;
 
 		struct backlight_device *device;
 
diff --git a/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c b/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
index de764dae1e66..9b0589cf8d17 100644
--- a/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
@@ -22,8 +22,26 @@
  *
  */
 
+/*
+ * Laptops with Intel GPUs which have panels that support controlling the
+ * backlight through DP AUX can actually use two different interfaces: Intel's
+ * proprietary DP AUX backlight interface, and the standard VESA backlight
+ * interface. Unfortunately, at the time of writing this a lot of laptops will
+ * advertise support for the standard VESA backlight interface when they
+ * don't properly support it. However, on these systems the Intel backlight
+ * interface generally does work properly. Additionally, these systems will
+ * usually just indicate that they use PWM backlight controls in their VBIOS
+ * for some reason.
+ */
+
 #include "intel_display_types.h"
 #include "intel_dp_aux_backlight.h"
+#include "intel_panel.h"
+
+/* TODO:
+ * Implement HDR, right now we just implement the bare minimum to bring us back into SDR mode so we
+ * can make people's backlights work in the mean time
+ */
 
 /*
  * DP AUX registers for Intel's proprietary HDR backlight interface. We define
@@ -77,6 +95,178 @@
 
 #define INTEL_EDP_BRIGHTNESS_OPTIMIZATION_1                            0x359
 
+/* Intel EDP backlight callbacks */
+static bool
+intel_dp_aux_supports_hdr_backlight(struct intel_connector *connector)
+{
+	struct drm_i915_private *i915 = to_i915(connector->base.dev);
+	struct intel_dp *intel_dp = enc_to_intel_dp(connector->encoder);
+	struct drm_dp_aux *aux = &intel_dp->aux;
+	struct intel_panel *panel = &connector->panel;
+	int ret;
+	u8 tcon_cap[4];
+
+	ret = drm_dp_dpcd_read(aux, INTEL_EDP_HDR_TCON_CAP0, tcon_cap, sizeof(tcon_cap));
+	if (ret < 0)
+		return false;
+
+	if (!(tcon_cap[1] & INTEL_EDP_HDR_TCON_BRIGHTNESS_NITS_CAP))
+		return false;
+
+	if (tcon_cap[0] >= 1) {
+		drm_dbg_kms(&i915->drm, "Detected Intel HDR backlight interface version %d\n",
+			    tcon_cap[0]);
+	} else {
+		drm_dbg_kms(&i915->drm, "Detected unsupported HDR backlight interface version %d\n",
+			    tcon_cap[0]);
+		return false;
+	}
+
+	panel->backlight.edp.intel.sdr_uses_aux =
+		tcon_cap[2] & INTEL_EDP_SDR_TCON_BRIGHTNESS_AUX_CAP;
+
+	return true;
+}
+
+static u32
+intel_dp_aux_hdr_get_backlight(struct intel_connector *connector, enum pipe pipe)
+{
+	struct drm_i915_private *i915 = to_i915(connector->base.dev);
+	struct intel_panel *panel = &connector->panel;
+	struct intel_dp *intel_dp = enc_to_intel_dp(connector->encoder);
+	u8 tmp;
+	u8 buf[2] = { 0 };
+
+	if (drm_dp_dpcd_readb(&intel_dp->aux, INTEL_EDP_HDR_GETSET_CTRL_PARAMS, &tmp) < 0) {
+		drm_err(&i915->drm, "Failed to read current backlight mode from DPCD\n");
+		return 0;
+	}
+
+	if (!(tmp & INTEL_EDP_HDR_TCON_BRIGHTNESS_AUX_ENABLE)) {
+		if (!panel->backlight.edp.intel.sdr_uses_aux) {
+			u32 pwm_level = panel->backlight.pwm_funcs->get(connector, pipe);
+
+			return intel_panel_backlight_level_from_pwm(connector, pwm_level);
+		}
+
+		/* Assume 100% brightness if backlight controls aren't enabled yet */
+		return panel->backlight.max;
+	}
+
+	if (drm_dp_dpcd_read(&intel_dp->aux, INTEL_EDP_BRIGHTNESS_NITS_LSB, buf, sizeof(buf)) < 0) {
+		drm_err(&i915->drm, "Failed to read brightness from DPCD\n");
+		return 0;
+	}
+
+	return (buf[1] << 8 | buf[0]);
+}
+
+static void
+intel_dp_aux_hdr_set_aux_backlight(const struct drm_connector_state *conn_state, u32 level)
+{
+	struct intel_connector *connector = to_intel_connector(conn_state->connector);
+	struct drm_device *dev = connector->base.dev;
+	struct intel_dp *intel_dp = enc_to_intel_dp(connector->encoder);
+	u8 buf[4] = { 0 };
+
+	buf[0] = level & 0xFF;
+	buf[1] = (level & 0xFF00) >> 8;
+
+	if (drm_dp_dpcd_write(&intel_dp->aux, INTEL_EDP_BRIGHTNESS_NITS_LSB, buf, 4) < 0)
+		drm_err(dev, "Failed to write brightness level to DPCD\n");
+}
+
+static void
+intel_dp_aux_hdr_set_backlight(const struct drm_connector_state *conn_state, u32 level)
+{
+	struct intel_connector *connector = to_intel_connector(conn_state->connector);
+	struct intel_panel *panel = &connector->panel;
+
+	if (panel->backlight.edp.intel.sdr_uses_aux) {
+		intel_dp_aux_hdr_set_aux_backlight(conn_state, level);
+	} else {
+		const u32 pwm_level = intel_panel_backlight_level_to_pwm(connector, level);
+
+		intel_panel_set_pwm_level(conn_state, pwm_level);
+	}
+}
+
+static void
+intel_dp_aux_hdr_enable_backlight(const struct intel_crtc_state *crtc_state,
+				  const struct drm_connector_state *conn_state, u32 level)
+{
+	struct intel_connector *connector = to_intel_connector(conn_state->connector);
+	struct intel_panel *panel = &connector->panel;
+	struct drm_i915_private *i915 = to_i915(connector->base.dev);
+	struct intel_dp *intel_dp = enc_to_intel_dp(connector->encoder);
+	int ret;
+	u8 old_ctrl, ctrl;
+
+	ret = drm_dp_dpcd_readb(&intel_dp->aux, INTEL_EDP_HDR_GETSET_CTRL_PARAMS, &old_ctrl);
+	if (ret < 0) {
+		drm_err(&i915->drm, "Failed to read current backlight control mode: %d\n", ret);
+		return;
+	}
+
+	ctrl = old_ctrl;
+	if (panel->backlight.edp.intel.sdr_uses_aux) {
+		ctrl |= INTEL_EDP_HDR_TCON_BRIGHTNESS_AUX_ENABLE;
+		intel_dp_aux_hdr_set_aux_backlight(conn_state, level);
+	} else {
+		u32 pwm_level = intel_panel_backlight_level_to_pwm(connector, level);
+
+		panel->backlight.pwm_funcs->enable(crtc_state, conn_state, pwm_level);
+
+		ctrl &= ~INTEL_EDP_HDR_TCON_BRIGHTNESS_AUX_ENABLE;
+	}
+
+	if (ctrl != old_ctrl)
+		if (drm_dp_dpcd_writeb(&intel_dp->aux, INTEL_EDP_HDR_GETSET_CTRL_PARAMS, ctrl) < 0)
+			drm_err(&i915->drm, "Failed to configure DPCD brightness controls\n");
+}
+
+static void
+intel_dp_aux_hdr_disable_backlight(const struct drm_connector_state *conn_state, u32 level)
+{
+	struct intel_connector *connector = to_intel_connector(conn_state->connector);
+	struct intel_panel *panel = &connector->panel;
+
+	/* Nothing to do for AUX based backlight controls */
+	if (panel->backlight.edp.intel.sdr_uses_aux)
+		return;
+
+	/* Note we want the actual pwm_level to be 0, regardless of pwm_min */
+	panel->backlight.pwm_funcs->disable(conn_state, intel_panel_invert_pwm_level(connector, 0));
+}
+
+static int
+intel_dp_aux_hdr_setup_backlight(struct intel_connector *connector, enum pipe pipe)
+{
+	struct drm_i915_private *i915 = to_i915(connector->base.dev);
+	struct intel_panel *panel = &connector->panel;
+	int ret;
+
+	if (panel->backlight.edp.intel.sdr_uses_aux) {
+		drm_dbg_kms(&i915->drm, "SDR backlight is controlled through DPCD\n");
+	} else {
+		drm_dbg_kms(&i915->drm, "SDR backlight is controlled through PWM\n");
+
+		ret = panel->backlight.pwm_funcs->setup(connector, pipe);
+		if (ret < 0) {
+			drm_err(&i915->drm,
+				"Failed to setup SDR backlight controls through PWM: %d\n", ret);
+			return ret;
+		}
+	}
+
+	panel->backlight.max = 512;
+	panel->backlight.min = 0;
+	panel->backlight.level = intel_dp_aux_hdr_get_backlight(connector, pipe);
+	panel->backlight.enabled = panel->backlight.level != 0;
+
+	return 0;
+}
+
 /* VESA backlight callbacks */
 static void set_vesa_backlight_enable(struct intel_dp *intel_dp, bool enable)
 {
@@ -195,7 +385,7 @@ static bool intel_dp_aux_vesa_set_pwm_freq(struct intel_connector *connector)
 {
 	struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
 	struct intel_dp *intel_dp = intel_attached_dp(connector);
-	const u8 pn = connector->panel.backlight.pwmgen_bit_count;
+	const u8 pn = connector->panel.backlight.edp.vesa.pwmgen_bit_count;
 	int freq, fxp, f, fxp_actual, fxp_min, fxp_max;
 
 	freq = dev_priv->vbt.backlight.pwm_freq_hz;
@@ -236,6 +426,7 @@ intel_dp_aux_vesa_enable_backlight(const struct intel_crtc_state *crtc_state,
 	struct drm_i915_private *i915 = dp_to_i915(intel_dp);
 	struct intel_panel *panel = &connector->panel;
 	u8 dpcd_buf, new_dpcd_buf, edp_backlight_mode;
+	u8 pwmgen_bit_count = panel->backlight.edp.vesa.pwmgen_bit_count;
 
 	if (drm_dp_dpcd_readb(&intel_dp->aux,
 			DP_EDP_BACKLIGHT_MODE_SET_REGISTER, &dpcd_buf) != 1) {
@@ -256,7 +447,7 @@ intel_dp_aux_vesa_enable_backlight(const struct intel_crtc_state *crtc_state,
 
 		if (drm_dp_dpcd_writeb(&intel_dp->aux,
 				       DP_EDP_PWMGEN_BIT_COUNT,
-				       panel->backlight.pwmgen_bit_count) < 0)
+				       pwmgen_bit_count) < 0)
 			drm_dbg_kms(&i915->drm,
 				    "Failed to write aux pwmgen bit count\n");
 
@@ -364,7 +555,7 @@ static u32 intel_dp_aux_vesa_calc_max_backlight(struct intel_connector *connecto
 			    "Failed to write aux pwmgen bit count\n");
 		return max_backlight;
 	}
-	panel->backlight.pwmgen_bit_count = pn;
+	panel->backlight.edp.vesa.pwmgen_bit_count = pn;
 
 	max_backlight = (1 << pn) - 1;
 
@@ -405,6 +596,14 @@ intel_dp_aux_supports_vesa_backlight(struct intel_connector *connector)
 	return false;
 }
 
+static const struct intel_panel_bl_funcs intel_dp_hdr_bl_funcs = {
+	.setup = intel_dp_aux_hdr_setup_backlight,
+	.enable = intel_dp_aux_hdr_enable_backlight,
+	.disable = intel_dp_aux_hdr_disable_backlight,
+	.set = intel_dp_aux_hdr_set_backlight,
+	.get = intel_dp_aux_hdr_get_backlight,
+};
+
 static const struct intel_panel_bl_funcs intel_dp_vesa_bl_funcs = {
 	.setup = intel_dp_aux_vesa_setup_backlight,
 	.enable = intel_dp_aux_vesa_enable_backlight,
@@ -413,36 +612,34 @@ static const struct intel_panel_bl_funcs intel_dp_vesa_bl_funcs = {
 	.get = intel_dp_aux_vesa_get_backlight,
 };
 
-int intel_dp_aux_init_backlight_funcs(struct intel_connector *intel_connector)
+int intel_dp_aux_init_backlight_funcs(struct intel_connector *connector)
 {
-	struct intel_panel *panel = &intel_connector->panel;
-	struct intel_dp *intel_dp = enc_to_intel_dp(intel_connector->encoder);
+	struct drm_device *dev = connector->base.dev;
+	struct intel_panel *panel = &connector->panel;
+	struct intel_dp *intel_dp = enc_to_intel_dp(connector->encoder);
 	struct drm_i915_private *i915 = dp_to_i915(intel_dp);
 
-	if (i915->params.enable_dpcd_backlight == 0 ||
-	    !intel_dp_aux_supports_vesa_backlight(intel_connector))
+	if (i915->params.enable_dpcd_backlight == 0)
 		return -ENODEV;
 
 	/*
-	 * There are a lot of machines that don't advertise the backlight
-	 * control interface to use properly in their VBIOS, :\
+	 * A lot of eDP panels in the wild will report supporting both the
+	 * Intel proprietary backlight control interface, and the VESA
+	 * backlight control interface. Many of these panels are liars though,
+	 * and will only work with the Intel interface. So, always probe for
+	 * that first.
 	 */
-	if (i915->vbt.backlight.type !=
-	    INTEL_BACKLIGHT_VESA_EDP_AUX_INTERFACE &&
-	    i915->params.enable_dpcd_backlight != 1 &&
-	    !drm_dp_has_quirk(&intel_dp->desc, intel_dp->edid_quirks,
-			      DP_QUIRK_FORCE_DPCD_BACKLIGHT)) {
-		drm_info(&i915->drm,
-			 "Panel advertises DPCD backlight support, but "
-			 "VBT disagrees. If your backlight controls "
-			 "don't work try booting with "
-			 "i915.enable_dpcd_backlight=1. If your machine "
-			 "needs this, please file a _new_ bug report on "
-			 "drm/i915, see " FDO_BUG_URL " for details.\n");
-		return -ENODEV;
+	if (intel_dp_aux_supports_hdr_backlight(connector)) {
+		drm_dbg_kms(dev, "Using Intel proprietary eDP backlight controls\n");
+		panel->backlight.funcs = &intel_dp_hdr_bl_funcs;
+		return 0;
 	}
 
-	panel->backlight.funcs = &intel_dp_vesa_bl_funcs;
+	if (intel_dp_aux_supports_vesa_backlight(connector)) {
+		drm_dbg_kms(dev, "Using VESA eDP backlight controls\n");
+		panel->backlight.funcs = &intel_dp_vesa_bl_funcs;
+		return 0;
+	}
 
-	return 0;
+	return -ENODEV;
 }
diff --git a/drivers/gpu/drm/i915/display/intel_panel.c b/drivers/gpu/drm/i915/display/intel_panel.c
index 79e73e3f700c..5fdf52643150 100644
--- a/drivers/gpu/drm/i915/display/intel_panel.c
+++ b/drivers/gpu/drm/i915/display/intel_panel.c
@@ -511,7 +511,7 @@ static u32 scale_hw_to_user(struct intel_connector *connector,
 		     0, user_max);
 }
 
-static u32 intel_panel_invert_pwm_level(struct intel_connector *connector, u32 val)
+u32 intel_panel_invert_pwm_level(struct intel_connector *connector, u32 val)
 {
 	struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
 	struct intel_panel *panel = &connector->panel;
@@ -539,6 +539,36 @@ void intel_panel_set_pwm_level(const struct drm_connector_state *conn_state, u32
 	panel->backlight.pwm_funcs->set(conn_state, val);
 }
 
+u32 intel_panel_backlight_level_to_pwm(struct intel_connector *connector, u32 val)
+{
+	struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
+	struct intel_panel *panel = &connector->panel;
+
+	drm_WARN_ON_ONCE(&dev_priv->drm,
+			 panel->backlight.max == 0 || panel->backlight.pwm_level_max == 0);
+
+	val = scale(val, panel->backlight.min, panel->backlight.max,
+		    panel->backlight.pwm_level_min, panel->backlight.pwm_level_max);
+
+	return intel_panel_invert_pwm_level(connector, val);
+}
+
+u32 intel_panel_backlight_level_from_pwm(struct intel_connector *connector, u32 val)
+{
+	struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
+	struct intel_panel *panel = &connector->panel;
+
+	drm_WARN_ON_ONCE(&dev_priv->drm,
+			 panel->backlight.max == 0 || panel->backlight.pwm_level_max == 0);
+
+	if (dev_priv->params.invert_brightness > 0 ||
+	    (dev_priv->params.invert_brightness == 0 && dev_priv->quirks & QUIRK_INVERT_BRIGHTNESS))
+		val = panel->backlight.pwm_level_max - (val - panel->backlight.pwm_level_min);
+
+	return scale(val, panel->backlight.pwm_level_min, panel->backlight.pwm_level_max,
+		     panel->backlight.min, panel->backlight.max);
+}
+
 static u32 lpt_get_backlight(struct intel_connector *connector, enum pipe unused)
 {
 	struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
@@ -2127,10 +2157,6 @@ intel_panel_init_backlight_funcs(struct intel_panel *panel)
 		container_of(panel, struct intel_connector, panel);
 	struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
 
-	if (connector->base.connector_type == DRM_MODE_CONNECTOR_eDP &&
-	    intel_dp_aux_init_backlight_funcs(connector) == 0)
-		return;
-
 	if (connector->base.connector_type == DRM_MODE_CONNECTOR_DSI &&
 	    intel_dsi_dcs_init_backlight_funcs(connector) == 0)
 		return;
@@ -2158,6 +2184,10 @@ intel_panel_init_backlight_funcs(struct intel_panel *panel)
 		panel->backlight.pwm_funcs = &i9xx_pwm_funcs;
 	}
 
+	if (connector->base.connector_type == DRM_MODE_CONNECTOR_eDP &&
+	    intel_dp_aux_init_backlight_funcs(connector) == 0)
+		return;
+
 	/* We're using a standard PWM backlight interface */
 	panel->backlight.funcs = &pwm_bl_funcs;
 }
diff --git a/drivers/gpu/drm/i915/display/intel_panel.h b/drivers/gpu/drm/i915/display/intel_panel.h
index 5b813fe90557..1d340f77bffc 100644
--- a/drivers/gpu/drm/i915/display/intel_panel.h
+++ b/drivers/gpu/drm/i915/display/intel_panel.h
@@ -49,6 +49,10 @@ struct drm_display_mode *
 intel_panel_edid_fixed_mode(struct intel_connector *connector);
 struct drm_display_mode *
 intel_panel_vbt_fixed_mode(struct intel_connector *connector);
+void intel_panel_set_pwm_level(const struct drm_connector_state *conn_state, u32 level);
+u32 intel_panel_invert_pwm_level(struct intel_connector *connector, u32 level);
+u32 intel_panel_backlight_level_to_pwm(struct intel_connector *connector, u32 level);
+u32 intel_panel_backlight_level_from_pwm(struct intel_connector *connector, u32 val);
 
 #if IS_ENABLED(CONFIG_BACKLIGHT_CLASS_DEVICE)
 int intel_backlight_device_register(struct intel_connector *connector);