I so totally suck.
This can cause a black screen if (for whatever reason) the bios
hasn't set this bit itself.
This regression has been introduced in
commit 7cf4160148136deb31ee5f2802857dd935a38529
Author: Daniel Vetter <daniel.vetter at ffwll.ch>
Date: Tue Jun 5 10:07:09 2012 +0200
drm/i915: clear up backlight #define confusion on gen4+
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=51463
Signed-Off-by: Daniel Vetter <daniel.vetter at ffwll.ch>
---
drivers/gpu/drm/i915/i915_reg.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index bd1cda2..45c6703 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -1921,7 +1921,7 @@
/* PCH CTL1 is totally different, all but the below bits are reserved. CTL2 is
* like the normal CTL from gen4 and earlier. Hooray for confusing naming. */
#define BLC_PWM_PCH_CTL1 0xc8250
-#define BLM_PCH_PWM_ENABLE (1 << 30)
+#define BLM_PCH_PWM_ENABLE (1 << 31)
#define BLM_PCH_OVERRIDE_ENABLE (1 << 30)
#define BLM_PCH_POLARITY (1 << 29)
#define BLC_PWM_PCH_CTL2 0xc8254
--
1.7.10.2
