[PATCH] drm/i915: Fix inconsistent backlight level during disabled

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?idA926
BugLink: https://bugs.launchpad.net/ubuntu/+...bug/872652

Tested-by: Kamal Mostafa <kamal@canonical.com>
Cc: Alex Davis <alex14641@yahoo.com>
Cc: <stable@kernel.org>
Signed-off-by: Takashi Iwai <tiwai@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

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