[Raring SRU][PULL] fix XPS13-FHD backlight regression

Kamal Mostafa kamal at canonical.com
Fri Apr 19 16:41:38 UTC 2013

Bug reference:

	XPS13 backlight stopped working after update 3.8.0-18.28


My recent sauce patch for LP: #1162026 (Raring 9742db3) applied a quirk to
fix the backlight controls on two variants of the Dell XPS13, but it turns
out that the quirk is only appropriate for the original 768p model (there
was some misunderstanding about which models needed it).

The new Dell XPS13 "FHD" 1080p model is actually adversely affected by the
quirk, yielding dark screen on boot and no backlight controls.  This patch
removes the 1080p model from the dmi quirk table, restoring its backlight
behavior to normal functionality.


The bug reporter in LP: #1169376 has confirmed that a test kernel with the
patch applied fixes it for his 1080p model.  I have confirmed that the
original quirk patch still works on my 768p model.

[Regression Potential]

Low regression potential: the change only affects the Dell XPS 13 "FHD" 1080p
model, returning its i915 backlight controls to the standard mainline
(pre 3.8.0-18.28) behavior.



-------- >8 ----------------------------------------------------

The following changes since commit 10e251b7b13b2c727d58a7d3ed4451667366ad12:

  UBUNTU: SAUCE: (no-up) ACPI: Disable Windows 8 compatibility for some Lenovo ThinkPads (2013-04-19 07:29:30 -0700)

are available in the git repository at:

  git://kernel.ubuntu.com/kamal/ubuntu-raring.git lp1169376-xps13-fhd

for you to fetch changes up to ba44c190aafad79f11e6b5477de26f81b8fdb3ac:

  UBUNTU: SAUCE: (no-up) drm/i915: quirk no PCH_PWM_ENABLE only Dell XPS13 SandyBridge (2013-04-19 08:52:52 -0700)

Kamal Mostafa (1):
      UBUNTU: SAUCE: (no-up) drm/i915: quirk no PCH_PWM_ENABLE only Dell XPS13 SandyBridge

 drivers/gpu/drm/i915/intel_display.c |    3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index d7231cb..b56b846 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -8893,9 +8893,8 @@ static const struct intel_dmi_quirk intel_dmi_quirks[] = {
 static struct intel_quirk intel_quirks[] = {
-	/* Dell XPS13 models */
+	/* Dell XPS13 SandyBridge */
 	{ 0x0116, 0x1028, 0x052e, quirk_no_pcm_pwm_enable },
-	{ 0x0166, 0x1028, 0x058b, quirk_no_pcm_pwm_enable },
 	/* HP Mini needs pipe A force quirk (LP: #322104) */
 	{ 0x27ae, 0x103c, 0x361a, quirk_pipea_force },

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