When the brightness property is inquired while the backlight is disabled, the driver returns a wrong value (zero) because it probes the value after the backlight was turned off. This caused a black screen even after the backlight is enabled again. It should return the internal backlight_level instead, so that it won't be influenced by the backlight-enable state. BugLink: https://bugs.freedesktop.org/show_bug.cgi?id=41926 BugLink: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/872652 Tested-by: Kamal Mostafa <kamal at canonical.com> Cc: Alex Davis <alex14641 at yahoo.com> Cc: <stable at kernel.org> Signed-off-by: Takashi Iwai <tiwai at suse.de> --- drivers/gpu/drm/i915/intel_panel.c | 3 ++- 1 files changed, 2 insertions(+), 1 deletions(-) diff --git a/drivers/gpu/drm/i915/intel_panel.c b/drivers/gpu/drm/i915/intel_panel.c index 499d4c0..21f60b7 100644 --- a/drivers/gpu/drm/i915/intel_panel.c +++ b/drivers/gpu/drm/i915/intel_panel.c @@ -326,7 +326,8 @@ static int intel_panel_update_status(struct backlight_device *bd) static int intel_panel_get_brightness(struct backlight_device *bd) { struct drm_device *dev = bl_get_data(bd); - return intel_panel_get_backlight(dev); + struct drm_i915_private *dev_priv = dev->dev_private; + return dev_priv->backlight_level; } static const struct backlight_ops intel_panel_bl_ops = { -- 1.7.7
