Re: BACKLIGHT_CONTROL and xrandr

[Matthew Garrett <mjg59@srcf.ucam.org>]

On Mon, Apr 12, 2010 at 06:19:20PM +0100, Matthew Garrett wrote:
> Can you give this patch a try? It's not ready for upstream yet, but 
> ought to work.

It would, of course, be more useful if I included the patch.

commit bd599ffa48a679679434109ead29fcdf108ccc77
Author: Matthew Garrett <mjg@redhat.com>
Date:   Wed Mar 31 16:36:00 2010 -0400

    intel: Add native backlight control

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index aba8260..40f6684 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -33,6 +33,7 @@
 #include "i915_reg.h"
 #include "intel_bios.h"
 #include <linux/io-mapping.h>
+#include <linux/backlight.h>
 
 /* General customization:
  */
@@ -628,6 +629,8 @@ typedef struct drm_i915_private {
 	u8 max_delay;
 
 	enum no_fbc_reason no_fbc_reason;
+
+	struct backlight_device *backlight;
 } drm_i915_private_t;
 
 /** driver private structure attached to each drm_gem_object */
diff --git a/drivers/gpu/drm/i915/i915_opregion.c b/drivers/gpu/drm/i915/i915_opregion.c
index 7cc8410..ea71e65 100644
--- a/drivers/gpu/drm/i915/i915_opregion.c
+++ b/drivers/gpu/drm/i915/i915_opregion.c
@@ -31,9 +31,9 @@
 #include "drmP.h"
 #include "i915_drm.h"
 #include "i915_drv.h"
+#include "intel_drv.h"
 
 #define PCI_ASLE 0xe4
-#define PCI_LBPC 0xf4
 #define PCI_ASLS 0xfc
 
 #define OPREGION_SZ            (8*1024)
@@ -151,37 +151,10 @@ static u32 asle_set_backlight(struct drm_device *dev, u32 bclp)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	struct opregion_asle *asle = dev_priv->opregion.asle;
-	u32 blc_pwm_ctl, blc_pwm_ctl2;
-	u32 max_backlight, level, shift;
-
-	if (!(bclp & ASLE_BCLP_VALID))
-		return ASLE_BACKLIGHT_FAIL;
-
-	bclp &= ASLE_BCLP_MSK;
-	if (bclp < 0 || bclp > 255)
-		return ASLE_BACKLIGHT_FAIL;
-
-	blc_pwm_ctl = I915_READ(BLC_PWM_CTL);
-	blc_pwm_ctl2 = I915_READ(BLC_PWM_CTL2);
-
-	if (IS_I965G(dev) && (blc_pwm_ctl2 & BLM_COMBINATION_MODE))
-		pci_write_config_dword(dev->pdev, PCI_LBPC, bclp);
-	else {
-		if (IS_PINEVIEW(dev)) {
-			blc_pwm_ctl &= ~(BACKLIGHT_DUTY_CYCLE_MASK - 1);
-			max_backlight = (blc_pwm_ctl & BACKLIGHT_MODULATION_FREQ_MASK) >> 
-					BACKLIGHT_MODULATION_FREQ_SHIFT;
-			shift = BACKLIGHT_DUTY_CYCLE_SHIFT + 1;
-		} else {
-			blc_pwm_ctl &= ~BACKLIGHT_DUTY_CYCLE_MASK;
-			max_backlight = ((blc_pwm_ctl & BACKLIGHT_MODULATION_FREQ_MASK) >> 
-					BACKLIGHT_MODULATION_FREQ_SHIFT) * 2;
-			shift = BACKLIGHT_DUTY_CYCLE_SHIFT;
-		}
-		level = (bclp * max_backlight) / 255;
-		I915_WRITE(BLC_PWM_CTL, blc_pwm_ctl | (level << shift));
-	}
-	asle->cblv = (bclp*0x64)/0xff | ASLE_CBLV_VALID;
+	u32 max = intel_lvds_get_max_backlight(dev);
+
+	asle->cblv = (bclp * 100 / 255) | ASLE_CBLV_VALID;
+	intel_lvds_set_backlight(dev, max * bclp / 255);
 
 	return 0;
 }
@@ -247,36 +220,6 @@ void opregion_asle_intr(struct drm_device *dev)
 	asle->aslc = asle_stat;
 }
 
-static u32 asle_set_backlight_ironlake(struct drm_device *dev, u32 bclp)
-{
-	struct drm_i915_private *dev_priv = dev->dev_private;
-	struct opregion_asle *asle = dev_priv->opregion.asle;
-	u32 cpu_pwm_ctl, pch_pwm_ctl2;
-	u32 max_backlight, level;
-
-	if (!(bclp & ASLE_BCLP_VALID))
-		return ASLE_BACKLIGHT_FAILED;
-
-	bclp &= ASLE_BCLP_MSK;
-	if (bclp < 0 || bclp > 255)
-		return ASLE_BACKLIGHT_FAILED;
-
-	cpu_pwm_ctl = I915_READ(BLC_PWM_CPU_CTL);
-	pch_pwm_ctl2 = I915_READ(BLC_PWM_PCH_CTL2);
-	/* get the max PWM frequency */
-	max_backlight = (pch_pwm_ctl2 >> 16) & BACKLIGHT_DUTY_CYCLE_MASK;
-	/* calculate the expected PMW frequency */
-	level = (bclp * max_backlight) / 255;
-	/* reserve the high 16 bits */
-	cpu_pwm_ctl &= ~(BACKLIGHT_DUTY_CYCLE_MASK);
-	/* write the updated PWM frequency */
-	I915_WRITE(BLC_PWM_CPU_CTL, cpu_pwm_ctl | level);
-
-	asle->cblv = (bclp*0x64)/0xff | ASLE_CBLV_VALID;
-
-	return 0;
-}
-
 void ironlake_opregion_gse_intr(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
@@ -300,7 +243,7 @@ void ironlake_opregion_gse_intr(struct drm_device *dev)
 	}
 
 	if (asle_req & ASLE_SET_BACKLIGHT)
-		asle_stat |= asle_set_backlight_ironlake(dev, asle->bclp);
+		asle_stat |= asle_set_backlight(dev, asle->bclp);
 
 	if (asle_req & ASLE_SET_PFIT) {
 		DRM_DEBUG_DRIVER("Pfit is not supported\n");
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index 3a467ca..1c35f67 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -171,6 +171,9 @@ extern void intel_dvo_init(struct drm_device *dev);
 extern void intel_tv_init(struct drm_device *dev);
 extern void intel_mark_busy(struct drm_device *dev, struct drm_gem_object *obj);
 extern void intel_lvds_init(struct drm_device *dev);
+extern u32 intel_lvds_get_max_backlight(struct drm_device *dev);
+extern u32 intel_lvds_get_backlight(struct drm_device *dev);
+extern void intel_lvds_set_backlight(struct drm_device *dev, int level);
 extern void intel_dp_init(struct drm_device *dev, int dp_reg);
 void
 intel_dp_set_m_n(struct drm_crtc *crtc, struct drm_display_mode *mode,
diff --git a/drivers/gpu/drm/i915/intel_lvds.c b/drivers/gpu/drm/i915/intel_lvds.c
index 2b3fa7a..ee2a06f 100644
--- a/drivers/gpu/drm/i915/intel_lvds.c
+++ b/drivers/gpu/drm/i915/intel_lvds.c
@@ -38,6 +38,7 @@
 #include "i915_drm.h"
 #include "i915_drv.h"
 #include <linux/acpi.h>
+#include <linux/backlight.h>
 
 /* Private structure for the integrated LVDS support */
 struct intel_lvds_priv {
@@ -47,43 +48,174 @@ struct intel_lvds_priv {
 };
 
 /**
- * Sets the backlight level.
- *
- * \param level backlight level, from 0 to intel_lvds_get_max_backlight().
+ * Returns the maximum level of the backlight duty cycle field.
  */
-static void intel_lvds_set_backlight(struct drm_device *dev, int level)
+u32 intel_lvds_get_max_backlight(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
-	u32 blc_pwm_ctl, reg;
+	u32 reg;
+	int value;
+	bool combo;
 
-	if (HAS_PCH_SPLIT(dev))
-		reg = BLC_PWM_CPU_CTL;
+	if (IS_I965G(dev))
+		combo = I915_READ(BLC_PWM_CTL2) & BLM_COMBINATION_MODE;
+	else
+		combo = I915_READ(BLC_PWM_CTL) & BLM_LEGACY_MODE;
+
+	if (IS_IRONLAKE(dev))
+		reg = BLC_PWM_PCH_CTL2;
 	else
 		reg = BLC_PWM_CTL;
 
-	blc_pwm_ctl = I915_READ(reg) & ~BACKLIGHT_DUTY_CYCLE_MASK;
-	I915_WRITE(reg, (blc_pwm_ctl |
-				 (level << BACKLIGHT_DUTY_CYCLE_SHIFT)));
+	value = ((I915_READ(reg) & BACKLIGHT_MODULATION_FREQ_MASK) >>
+		 BACKLIGHT_MODULATION_FREQ_SHIFT);
+
+	if (!IS_PINEVIEW(dev))
+		value *= 2;
+
+	if (combo) {
+		value *= 0xff;
+		value /= 2;
+	}
+
+	return value;
 }
 
 /**
- * Returns the maximum level of the backlight duty cycle field.
+ * Returns the level of the backlight duty cycle field.
  */
-static u32 intel_lvds_get_max_backlight(struct drm_device *dev)
+u32 intel_lvds_get_backlight(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	u32 reg;
+	u8 lbpc;
+	int value;
+	bool combo;
 
-	if (HAS_PCH_SPLIT(dev))
-		reg = BLC_PWM_PCH_CTL2;
+	if (IS_I965G(dev))
+		combo = I915_READ(BLC_PWM_CTL2) & BLM_COMBINATION_MODE;
+	else
+		combo = I915_READ(BLC_PWM_CTL) & BLM_LEGACY_MODE;
+
+	if (IS_IRONLAKE(dev))
+		reg = BLC_PWM_CPU_CTL;
 	else
 		reg = BLC_PWM_CTL;
 
-	return ((I915_READ(reg) & BACKLIGHT_MODULATION_FREQ_MASK) >>
-		BACKLIGHT_MODULATION_FREQ_SHIFT) * 2;
+	value = I915_READ(reg) & BACKLIGHT_DUTY_CYCLE_MASK;
+
+	if (IS_PINEVIEW(dev))
+		value /= 2;
+
+	if (combo) {
+		value &= ~0x1;
+		pci_read_config_byte(dev->pdev, LBB, &lbpc);
+		value *= lbpc;
+		value /= 2;
+	}
+
+	return value;
 }
 
 /**
+ * Sets the backlight level.
+  *
+  * \param level backlight level, from 0 to intel_lvds_get_max_backlight().
+  */
+void intel_lvds_set_backlight(struct drm_device *dev, int level)
+{
+        struct drm_i915_private *dev_priv = dev->dev_private;
+        u32 blc_pwm_ctl, reg;
+	bool combo;
+	u8 lbpc;
+
+	if (IS_I965G(dev))
+		combo = I915_READ(BLC_PWM_CTL2) & BLM_COMBINATION_MODE;
+	else
+		combo = I915_READ(BLC_PWM_CTL) & BLM_LEGACY_MODE;
+
+	if (IS_IRONLAKE(dev))
+		reg = BLC_PWM_CPU_CTL;
+	else
+		reg = BLC_PWM_CTL;
+
+	if (combo) {
+		int maximum = intel_lvds_get_max_backlight(dev);
+		lbpc = level * 0xfe / maximum;
+		lbpc += 1;
+		pci_write_config_byte(dev->pdev, LBB, lbpc);
+		level /= lbpc;
+		level <<= 1;
+	}
+
+	if (IS_PINEVIEW(dev)) {
+		blc_pwm_ctl = I915_READ(reg) & ~(BACKLIGHT_DUTY_CYCLE_MASK - 1);
+		I915_WRITE(reg, (blc_pwm_ctl |
+				 (level << (BACKLIGHT_DUTY_CYCLE_SHIFT + 1))));
+	} else {
+		blc_pwm_ctl = I915_READ(reg) & ~BACKLIGHT_DUTY_CYCLE_MASK;
+		I915_WRITE(reg, blc_pwm_ctl |
+			   (level << BACKLIGHT_DUTY_CYCLE_SHIFT));
+	}
+}
+
+#ifdef CONFIG_BACKLIGHT_CLASS_DEVICE
+static int intel_lvds_update_status(struct backlight_device *bd)
+{
+	struct drm_device *dev = bl_get_data(bd);
+	intel_lvds_set_backlight(dev, bd->props.brightness);
+	return 0;
+}
+
+static int intel_lvds_get_brightness(struct backlight_device *bd)
+{
+	struct drm_device *dev = bl_get_data(bd);
+	return intel_lvds_get_backlight(dev);
+}
+
+static const struct backlight_ops intel_lvds_bl_ops = {
+	.update_status = intel_lvds_update_status,
+	.get_brightness = intel_lvds_get_brightness,
+};
+
+static int intel_lvds_backlight_setup(struct drm_device *dev)
+{
+        struct drm_i915_private *dev_priv = dev->dev_private;
+	struct backlight_properties props;
+
+	props.max_brightness = intel_lvds_get_max_backlight(dev);
+	dev_priv->backlight = backlight_device_register("intel_backlight",
+							&dev->pdev->dev, dev,
+							&intel_lvds_bl_ops,
+							&props);
+	if (IS_ERR(dev_priv->backlight)) {
+		DRM_ERROR("Failed to register backlight: %ld\n",
+			  PTR_ERR(dev_priv->backlight));
+		dev_priv->backlight = NULL;
+		return -ENODEV;
+	}
+	dev_priv->backlight->props.brightness = intel_lvds_get_backlight(dev);
+	return 0;
+}
+
+static void intel_lvds_backlight_destroy(struct drm_device *dev) {
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	if (dev_priv->backlight)
+		backlight_device_unregister(dev_priv->backlight);
+}
+#else
+static int intel_lvds_backlight_setup(struct drm_device *dev)
+{
+	return 0;
+}
+
+static void intel_lvds_backlight_destroy(struct drm_device *dev)
+{
+	return;
+}
+#endif
+
+/**
  * Sets the power state for the panel.
  */
 static void intel_lvds_set_power(struct drm_device *dev, bool on)
@@ -164,8 +296,7 @@ static void intel_lvds_save(struct drm_connector *connector)
 	dev_priv->savePP_CONTROL = I915_READ(pp_ctl_reg);
 	dev_priv->savePP_DIVISOR = I915_READ(pp_div_reg);
 	dev_priv->saveBLC_PWM_CTL = I915_READ(pwm_ctl_reg);
-	dev_priv->backlight_duty_cycle = (dev_priv->saveBLC_PWM_CTL &
-				       BACKLIGHT_DUTY_CYCLE_MASK);
+	dev_priv->backlight_duty_cycle = intel_lvds_get_backlight(dev);
 
 	/*
 	 * If the light is off at server startup, just make it full brightness
@@ -562,8 +693,7 @@ static void intel_lvds_prepare(struct drm_encoder *encoder)
 		reg = BLC_PWM_CTL;
 
 	dev_priv->saveBLC_PWM_CTL = I915_READ(reg);
-	dev_priv->backlight_duty_cycle = (dev_priv->saveBLC_PWM_CTL &
-				       BACKLIGHT_DUTY_CYCLE_MASK);
+	dev_priv->backlight_duty_cycle = intel_lvds_get_backlight(dev);
 
 	intel_lvds_set_power(dev, false);
 }
@@ -717,6 +847,8 @@ static void intel_lvds_destroy(struct drm_connector *connector)
 	struct intel_output *intel_output = to_intel_output(connector);
 	struct drm_i915_private *dev_priv = dev->dev_private;
 
+	intel_lvds_backlight_destroy(dev);
+
 	if (intel_output->ddc_bus)
 		intel_i2c_destroy(intel_output->ddc_bus);
 	if (dev_priv->lid_notifier.notifier_call)
@@ -1128,6 +1260,9 @@ out:
 	/* keep the LVDS connector */
 	dev_priv->int_lvds_connector = connector;
 	drm_sysfs_connector_add(connector);
+
+	intel_lvds_backlight_setup(dev);
+
 	return;
 
 failed:

-- 
Matthew Garrett | mjg59@srcf.ucam.org