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drm/i915: disable CPU PWM also on LPT/SPT backlight disable 

Although we don't support or enable CPU PWM with LPT/SPT based systems,
it may have been enabled prior to loading the driver. Disable the CPU
PWM on LPT/SPT backlight disable to avoid warnings on LCPLL disable.

The issue has been present on BDW since BDW enabling, but was recently
introduced on HSW with

commit 437b15b801
Author: Jani Nikula <jani.nikula@intel.com>
Date:   Fri Sep 4 16:55:13 2015 +0300

    drm/i915: use pch backlight override on hsw too

Cc: Paulo Zanoni <paulo.r.zanoni@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reference: http://mid.gmane.org/87y4frhwsn.fsf@yhuang-dev.intel.com
Reported-by: kernel test robot <ying.huang@intel.com>
Tested-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1446033429-8006-1-git-send-email-jani.nikula@intel.com
hifive-unleashed-5.1
Jani Nikula 2015-10-28 13:57:09 +02:00
parent 5a37ed0a9e
commit 6675bce251
1 changed files with 14 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

14
drivers/gpu/drm/i915/intel_panel.c
View File

@ -732,6 +732,20 @@ static void lpt_disable_backlight(struct intel_connector *connector)
intel_panel_actually_set_backlight(connector, 0);
/*
* Although we don't support or enable CPU PWM with LPT/SPT based
* systems, it may have been enabled prior to loading the
* driver. Disable to avoid warnings on LCPLL disable.
*
* This needs rework if we need to add support for CPU PWM on PCH split
* platforms.
*/
tmp = I915_READ(BLC_PWM_CPU_CTL2);
if (tmp & BLM_PWM_ENABLE) {
DRM_DEBUG_KMS("cpu backlight was enabled, disabling\n");
I915_WRITE(BLC_PWM_CPU_CTL2, tmp & ~BLM_PWM_ENABLE);
}
tmp = I915_READ(BLC_PWM_PCH_CTL1);
I915_WRITE(BLC_PWM_PCH_CTL1, tmp & ~BLM_PCH_PWM_ENABLE);
}