drm/i915/bxt: backlight clock gating workaround
authorImre Deak <imre.deak@intel.com>
Tue, 1 Dec 2015 08:23:52 +0000 (10:23 +0200)
committerJani Nikula <jani.nikula@intel.com>
Wed, 2 Dec 2015 08:10:39 +0000 (10:10 +0200)
commitd965e7ac7a196c27e299c598bcb678ab71132dc1
treef61597b1defdafd0319ece60f218ca6f44676978
parent5075222b04a28bff6bf1c66a7baced787be6b6de
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
drivers/gpu/drm/i915/i915_reg.h
drivers/gpu/drm/i915/intel_pm.c