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 <[email protected]> Date: Fri Sep 4 16:55:13 2015 +0300 drm/i915: use pch backlight override on hsw too Reference: http://mid.gmane.org/[email protected] Reported-by: kernel test robot <[email protected]> Signed-off-by: Jani Nikula <[email protected]> --- 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 dd71e7f139e3..c9c94d05f3dd 100644 --- a/drivers/gpu/drm/i915/intel_panel.c +++ b/drivers/gpu/drm/i915/intel_panel.c @@ -731,6 +731,20 @@ 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
