From 6675bce251b6ec20ec09c07e941d9f664be4ae58 Mon Sep 17 00:00:00 2001 From: Jani Nikula Date: Wed, 28 Oct 2015 13:57:09 +0200 Subject: [PATCH] drm/i915: disable CPU PWM also on LPT/SPT backlight disable MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit 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 Date: Fri Sep 4 16:55:13 2015 +0300 drm/i915: use pch backlight override on hsw too Cc: Paulo Zanoni Cc: Ville Syrjälä Reference: http://mid.gmane.org/87y4frhwsn.fsf@yhuang-dev.intel.com Reported-by: kernel test robot Tested-by: Ville Syrjälä Signed-off-by: Jani Nikula Link: http://patchwork.freedesktop.org/patch/msgid/1446033429-8006-1-git-send-email-jani.nikula@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); } -- 2.20.1