drm/i915/bxt: backlight clock gating workaround
Per bspec, "Backlight PWM may stop in the asserted state, causing
backlight to stay fully on. WA: Before disabling PWM, set CLKGATE_DIS_0
0x46530 bit 13 PWM1 Gating Dis (for PWM1) or bit 14 PWM2 Gating Dis (for
PWM2). The bits can remain set without harm." (There's no workaround
name for this.)
This fixes some Broxton backlight issues.
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
[Jani: cleanup & commit message]
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1448958232-26520-3-git-send-email-jani.nikula@intel.com
diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index 1a12d44..04439e8 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -2973,6 +2973,13 @@
#define OGAMC0 _MMIO(0x30024)
/*
+ * GEN9 clock gating regs
+ */
+#define GEN9_CLKGATE_DIS_0 _MMIO(0x46530)
+#define PWM2_GATING_DIS (1 << 14)
+#define PWM1_GATING_DIS (1 << 13)
+
+/*
* Display engine regs
*/