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
