Also adding Cc: intel-gfx, please include that in follow-ups. Thanks, Jani.
On Tue, 29 Sep 2015, Jani Nikula <[email protected]> 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 <[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 > -- Jani Nikula, Intel Open Source Technology Center -- 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/
