drm/i915: quirk no PCH_PWM_ENABLE for Dell XPS13 backlight
BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=47941
BugLink: https://bugs.launchpad.net/bugs/1163720
BugLink: https://bugs.launchpad.net/bugs/1162026
Some machines suffer from non-functional backlight controls if
BLM_PCH_PWM_ENABLE is set, so provide a quirk to avoid doing so.
Apply this quirk to Dell XPS 13 models.
Tested-by: Eric Griffith <EGriffith92@gmail.com>
Tested-by: Kent Baxley <kent.baxley@canonical.com>
Cc: <stable@vger.kernel.org> # v3.8+
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
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 45010bb..67e2c1f 100644
--- a/drivers/gpu/drm/i915/intel_panel.c
+++ b/drivers/gpu/drm/i915/intel_panel.c
@@ -583,7 +583,8 @@
POSTING_READ(reg);
I915_WRITE(reg, tmp | BLM_PWM_ENABLE);
- if (HAS_PCH_SPLIT(dev)) {
+ if (HAS_PCH_SPLIT(dev) &&
+ !(dev_priv->quirks & QUIRK_NO_PCH_PWM_ENABLE)) {
tmp = I915_READ(BLC_PWM_PCH_CTL1);
tmp |= BLM_PCH_PWM_ENABLE;
tmp &= ~BLM_PCH_OVERRIDE_ENABLE;