[Intel-gfx] [PATCH RESEND] drm/i915: disable CPU PWM also on LPT/SPT backlight disable

[Jani Nikula]

On Wed, 28 Oct 2015, Ville Syrjälä <ville.syrjala at linux.intel.com> wrote:
> On Wed, Oct 28, 2015 at 01:57:09PM +0200, Jani Nikula wrote:
>> 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 437b15b8017e0d946453c10794b0c5d4591cf180
>> Author: Jani Nikula <jani.nikula at 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 at intel.com>
>> Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
>> Reference: http://mid.gmane.org/87y4frhwsn.fsf@yhuang-dev.intel.com
>> Reported-by: kernel test robot <ying.huang at intel.com>
>> Signed-off-by: Jani Nikula <jani.nikula at intel.com>
>
> Not seeing the warning anymore during
> ./scripts/run-tests.sh -t basic -x reload -x suspend
> on my HSW-ULT
>
> Tested-by: Ville Syrjälä <ville.syrjala at linux.intel.com>

Thanks, pushed to drm-intel-next-fixes.

BR,
Jani.

>
>> ---
>>  drivers/gpu/drm/i915/intel_panel.c | 14 ++++++++++++++
>>  1 file changed, 14 insertions(+)
>> 
>> diff --git a/drivers/gpu/drm/i915/intel_panel.c b/drivers/gpu/drm/i915/intel_panel.c
>> index b05c6d9b3be7..a24df35e11e7 100644
>> --- a/drivers/gpu/drm/i915/intel_panel.c
>> +++ b/drivers/gpu/drm/i915/intel_panel.c
>> @@ -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);
>>  }
>> -- 
>> 2.1.4
>
> -- 
> Ville Syrjälä
> Intel OTC

-- 
Jani Nikula, Intel Open Source Technology Center