[Intel-gfx] [PATCH] drm/i915: do not expose a dysfunctional backlight interface to userspace
Jani Nikula
jani.nikula at intel.com
Mon Sep 3 15:25:12 CEST 2012
Previously intel_panel_setup_backlight() would create a sysfs backlight
interface with max brightness of 1 if it was unable to figure out the max
backlight brightness. This rendered the backlight interface useless.
Do not create a dysfunctional backlight interface to begin with.
Signed-off-by: Jani Nikula <jani.nikula at intel.com>
---
See https://bugzilla.redhat.com/show_bug.cgi?id=752595
There's still a bug somewhere in the userspace as well; it should always
prefer the platform backlight interface over the raw one. This patch might
have the effect of hiding that particular userspace issue, but we shouldn't
be exporting a backlight interface that's useless no matter what.
---
drivers/gpu/drm/i915/intel_panel.c | 31 ++++++++++++++++++++++---------
1 file changed, 22 insertions(+), 9 deletions(-)
diff --git a/drivers/gpu/drm/i915/intel_panel.c b/drivers/gpu/drm/i915/intel_panel.c
index 3df4f5f..e019b23 100644
--- a/drivers/gpu/drm/i915/intel_panel.c
+++ b/drivers/gpu/drm/i915/intel_panel.c
@@ -162,19 +162,12 @@ static u32 i915_read_blc_pwm_ctl(struct drm_i915_private *dev_priv)
return val;
}
-u32 intel_panel_get_max_backlight(struct drm_device *dev)
+static u32 _intel_panel_get_max_backlight(struct drm_device *dev)
{
struct drm_i915_private *dev_priv = dev->dev_private;
u32 max;
max = i915_read_blc_pwm_ctl(dev_priv);
- if (max == 0) {
- /* XXX add code here to query mode clock or hardware clock
- * and program max PWM appropriately.
- */
- pr_warn_once("fixme: max PWM is zero\n");
- return 1;
- }
if (HAS_PCH_SPLIT(dev)) {
max >>= 16;
@@ -188,6 +181,22 @@ u32 intel_panel_get_max_backlight(struct drm_device *dev)
max *= 0xff;
}
+ return max;
+}
+
+u32 intel_panel_get_max_backlight(struct drm_device *dev)
+{
+ u32 max;
+
+ max = _intel_panel_get_max_backlight(dev);
+ if (max == 0) {
+ /* XXX add code here to query mode clock or hardware clock
+ * and program max PWM appropriately.
+ */
+ pr_warn_once("fixme: max PWM is zero\n");
+ return 1;
+ }
+
DRM_DEBUG_DRIVER("max backlight PWM = %d\n", max);
return max;
}
@@ -424,7 +433,11 @@ int intel_panel_setup_backlight(struct drm_device *dev)
memset(&props, 0, sizeof(props));
props.type = BACKLIGHT_RAW;
- props.max_brightness = intel_panel_get_max_backlight(dev);
+ props.max_brightness = _intel_panel_get_max_backlight(dev);
+ if (props.max_brightness == 0) {
+ DRM_ERROR("Failed to get maximum backlight value\n");
+ return -ENODEV;
+ }
dev_priv->backlight =
backlight_device_register("intel_backlight",
&connector->kdev, dev,
--
1.7.9.5
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