drm/i915/panel: Only record the backlight level when it is enabled

commit 47356eb67285014527a5ab87543ba1fae3d1e10a upstream.

By tracking the current status of the backlight we can prevent recording
the value of the current backlight when we have disabled it. And so
prevent restoring it to 'off' after an unbalanced sequence of
intel_lvds_disable/enable.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=22672
Tested-by: Alex Riesen <raa.lkml@gmail.com>
Tested-by: Larry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

5 files changed, 39 insertions, 8 deletions

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 409826da3099..d2896ebaba9f 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -329,6 +329,7 @@ typedef struct drm_i915_private {
 
 	/* LVDS info */
 	int backlight_level;  /* restore backlight to this value */
+	bool backlight_enabled;
 	struct drm_display_mode *panel_fixed_mode;
 	struct drm_display_mode *lfp_lvds_vbt_mode; /* if any */
 	struct drm_display_mode *sdvo_lvds_vbt_mode; /* if any */
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 394446d31691..3abd904ce435 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -5498,6 +5498,8 @@ static void intel_setup_outputs(struct drm_device *dev)
 		encoder->base.possible_clones =
 			intel_encoder_clones(dev, encoder->clone_mask);
 	}
+
+	intel_panel_setup_backlight(dev);
 }
 
 static void intel_user_framebuffer_destroy(struct drm_framebuffer *fb)
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index e52c6125bb1f..1e682938b9f9 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -256,6 +256,9 @@ extern void intel_pch_panel_fitting(struct drm_device *dev,
 extern u32 intel_panel_get_max_backlight(struct drm_device *dev);
 extern u32 intel_panel_get_backlight(struct drm_device *dev);
 extern void intel_panel_set_backlight(struct drm_device *dev, u32 level);
+extern void intel_panel_setup_backlight(struct drm_device *dev);
+extern void intel_panel_enable_backlight(struct drm_device *dev);
+extern void intel_panel_disable_backlight(struct drm_device *dev);
 
 extern void intel_crtc_load_lut(struct drm_crtc *crtc);
 extern void intel_encoder_prepare (struct drm_encoder *encoder);
diff --git a/drivers/gpu/drm/i915/intel_lvds.c b/drivers/gpu/drm/i915/intel_lvds.c
index 25bcedf386fd..3538e6babd0c 100644
--- a/drivers/gpu/drm/i915/intel_lvds.c
+++ b/drivers/gpu/drm/i915/intel_lvds.c
@@ -106,7 +106,7 @@ static void intel_lvds_enable(struct intel_lvds *intel_lvds)
 	I915_WRITE(ctl_reg, I915_READ(ctl_reg) | POWER_TARGET_ON);
 	POSTING_READ(lvds_reg);
 
-	intel_panel_set_backlight(dev, dev_priv->backlight_level);
+	intel_panel_enable_backlight(dev);
 }
 
 static void intel_lvds_disable(struct intel_lvds *intel_lvds)
@@ -123,8 +123,7 @@ static void intel_lvds_disable(struct intel_lvds *intel_lvds)
 		lvds_reg = LVDS;
 	}
 
-	dev_priv->backlight_level = intel_panel_get_backlight(dev);
-	intel_panel_set_backlight(dev, 0);
+	intel_panel_disable_backlight(dev);
 
 	I915_WRITE(ctl_reg, I915_READ(ctl_reg) & ~POWER_TARGET_ON);
 
@@ -395,8 +394,6 @@ static void intel_lvds_prepare(struct drm_encoder *encoder)
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	struct intel_lvds *intel_lvds = to_intel_lvds(encoder);
 
-	dev_priv->backlight_level = intel_panel_get_backlight(dev);
-
 	/* We try to do the minimum that is necessary in order to unlock
 	 * the registers for mode setting.
 	 *
@@ -427,9 +424,6 @@ static void intel_lvds_commit(struct drm_encoder *encoder)
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	struct intel_lvds *intel_lvds = to_intel_lvds(encoder);
 
-	if (dev_priv->backlight_level == 0)
-		dev_priv->backlight_level = intel_panel_get_max_backlight(dev);
-
 	/* Undo any unlocking done in prepare to prevent accidental
 	 * adjustment of the registers.
 	 */
diff --git a/drivers/gpu/drm/i915/intel_panel.c b/drivers/gpu/drm/i915/intel_panel.c
index 92ff8f385278..07014d96242b 100644
--- a/drivers/gpu/drm/i915/intel_panel.c
+++ b/drivers/gpu/drm/i915/intel_panel.c
@@ -218,3 +218,34 @@ void intel_panel_set_backlight(struct drm_device *dev, u32 level)
 		tmp &= ~BACKLIGHT_DUTY_CYCLE_MASK;
 	I915_WRITE(BLC_PWM_CTL, tmp | level);
 }
+
+void intel_panel_disable_backlight(struct drm_device *dev)
+{
+	struct drm_i915_private *dev_priv = dev->dev_private;
+
+	if (dev_priv->backlight_enabled) {
+		dev_priv->backlight_level = intel_panel_get_backlight(dev);
+		dev_priv->backlight_enabled = false;
+	}
+
+	intel_panel_set_backlight(dev, 0);
+}
+
+void intel_panel_enable_backlight(struct drm_device *dev)
+{
+	struct drm_i915_private *dev_priv = dev->dev_private;
+
+	if (dev_priv->backlight_level == 0)
+		dev_priv->backlight_level = intel_panel_get_max_backlight(dev);
+
+	intel_panel_set_backlight(dev, dev_priv->backlight_level);
+	dev_priv->backlight_enabled = true;
+}
+
+void intel_panel_setup_backlight(struct drm_device *dev)
+{
+	struct drm_i915_private *dev_priv = dev->dev_private;
+
+	dev_priv->backlight_level = intel_panel_get_max_backlight(dev);
+	dev_priv->backlight_enabled = dev_priv->backlight_level != 0;
+}