commit 46e69f3982f6ed0f2575ee11649bc77b7a89fd3e
author Jani Nikula <jani.nikula@intel.com> Tue Aug 23 10:10:05 2016 +0200
committer Maarten Lankhorst <maarten.lankhorst@linux.intel.com> Mon Aug 29 13:59:05 2016 +0200
tree 2399aa0464ba1faf1419aa5918730140b261b61f
parent ce5e2ac1a47ee4a13a05e2400c520f7de9b4becd

drm/i915/backlight: handle enabled but zero duty cycle at module load

Don't consider enabled but zero duty cycle backlight disabled. Clamp
level between min and max for sanity.

Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1471939811-9817-1-git-send-email-maarten.lankhorst@linux.intel.com
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>

drivers/gpu/drm/i915/intel_panel.c

diff --git a/drivers/gpu/drm/i915/intel_panel.c b/drivers/gpu/drm/i915/intel_panel.c
index 96c65d7..c10e9b0 100644
--- a/drivers/gpu/drm/i915/intel_panel.c
+++ b/drivers/gpu/drm/i915/intel_panel.c
@@ -1430,10 +1430,11 @@
 	panel->backlight.min = get_backlight_min_vbt(connector);
 
 	val = lpt_get_backlight(connector);
-	panel->backlight.level = intel_panel_compute_brightness(connector, val);
+	val = intel_panel_compute_brightness(connector, val);
+	panel->backlight.level = clamp(val, panel->backlight.min,
+				       panel->backlight.max);
 
-	panel->backlight.enabled = (pch_ctl1 & BLM_PCH_PWM_ENABLE) &&
-		panel->backlight.level != 0;
+	panel->backlight.enabled = pch_ctl1 & BLM_PCH_PWM_ENABLE;
 
 	return 0;
 }
@@ -1459,11 +1460,13 @@
 	panel->backlight.min = get_backlight_min_vbt(connector);
 
 	val = pch_get_backlight(connector);
-	panel->backlight.level = intel_panel_compute_brightness(connector, val);
+	val = intel_panel_compute_brightness(connector, val);
+	panel->backlight.level = clamp(val, panel->backlight.min,
+				       panel->backlight.max);
 
 	cpu_ctl2 = I915_READ(BLC_PWM_CPU_CTL2);
 	panel->backlight.enabled = (cpu_ctl2 & BLM_PWM_ENABLE) &&
-		(pch_ctl1 & BLM_PCH_PWM_ENABLE) && panel->backlight.level != 0;
+		(pch_ctl1 & BLM_PCH_PWM_ENABLE);
 
 	return 0;
 }
@@ -1498,9 +1501,11 @@
 	panel->backlight.min = get_backlight_min_vbt(connector);
 
 	val = i9xx_get_backlight(connector);
-	panel->backlight.level = intel_panel_compute_brightness(connector, val);
+	val = intel_panel_compute_brightness(connector, val);
+	panel->backlight.level = clamp(val, panel->backlight.min,
+				       panel->backlight.max);
 
-	panel->backlight.enabled = panel->backlight.level != 0;
+	panel->backlight.enabled = val != 0;
 
 	return 0;
 }
@@ -1530,10 +1535,11 @@
 	panel->backlight.min = get_backlight_min_vbt(connector);
 
 	val = i9xx_get_backlight(connector);
-	panel->backlight.level = intel_panel_compute_brightness(connector, val);
+	val = intel_panel_compute_brightness(connector, val);
+	panel->backlight.level = clamp(val, panel->backlight.min,
+				       panel->backlight.max);
 
-	panel->backlight.enabled = (ctl2 & BLM_PWM_ENABLE) &&
-		panel->backlight.level != 0;
+	panel->backlight.enabled = ctl2 & BLM_PWM_ENABLE;
 
 	return 0;
 }
@@ -1562,10 +1568,11 @@
 	panel->backlight.min = get_backlight_min_vbt(connector);
 
 	val = _vlv_get_backlight(dev_priv, pipe);
-	panel->backlight.level = intel_panel_compute_brightness(connector, val);
+	val = intel_panel_compute_brightness(connector, val);
+	panel->backlight.level = clamp(val, panel->backlight.min,
+				       panel->backlight.max);
 
-	panel->backlight.enabled = (ctl2 & BLM_PWM_ENABLE) &&
-		panel->backlight.level != 0;
+	panel->backlight.enabled = ctl2 & BLM_PWM_ENABLE;
 
 	return 0;
 }
@@ -1607,10 +1614,11 @@
 		return -ENODEV;
 
 	val = bxt_get_backlight(connector);
-	panel->backlight.level = intel_panel_compute_brightness(connector, val);
+	val = intel_panel_compute_brightness(connector, val);
+	panel->backlight.level = clamp(val, panel->backlight.min,
+				       panel->backlight.max);
 
-	panel->backlight.enabled = (pwm_ctl & BXT_BLC_PWM_ENABLE) &&
-		panel->backlight.level != 0;
+	panel->backlight.enabled = pwm_ctl & BXT_BLC_PWM_ENABLE;
 
 	return 0;
 }