drm/i915: do not expose a dysfunctional backlight interface to userspace
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@intel.com>
Tested-by: David Woodhouse <David.Woodhouse@intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
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 @@
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 @@
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 @@
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,