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.nik...@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.zan...@intel.com>
> Cc: Ville Syrjälä <ville.syrj...@linux.intel.com>
> Reference: http://mid.gmane.org/87y4frhwsn....@yhuang-dev.intel.com
> Reported-by: kernel test robot <ying.hu...@intel.com>
> Signed-off-by: Jani Nikula <jani.nik...@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.syrj...@linux.intel.com>
> ---
> 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
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