On Fri, Jul 19, 2013 at 03:02:01PM -0700, Kamal Mostafa wrote:

BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=47941 BugLink: https://bugs.launchpad.net/bugs/1163720 BugLink: https://bugs.launchpad.net/bugs/1162026

Some machines suffer from non-functional backlight controls if BLM_PCH_PWM_ENABLE is set, so provide a quirk to avoid doing so. Apply this quirk to Dell XPS 13 models.

Tested-by: Eric Griffith EGriffith92@gmail.com Tested-by: Kent Baxley kent.baxley@canonical.com Cc: stable@vger.kernel.org # v3.8+ Signed-off-by: Kamal Mostafa kamal@canonical.com

I still wonder what exactly's going on here, but for backlight stuff I've given up on avoiding quirks ;-) Thanks for digging into this, patch applied to -fixes. -Daniel

---

drivers/gpu/drm/i915/i915_drv.h | 1 + drivers/gpu/drm/i915/intel_display.c | 16 ++++++++++++++++ drivers/gpu/drm/i915/intel_panel.c | 3 ++- 3 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h index a416645..204c3ec 100644 --- a/drivers/gpu/drm/i915/i915_drv.h +++ b/drivers/gpu/drm/i915/i915_drv.h @@ -555,6 +555,7 @@ enum intel_sbi_destination { #define QUIRK_PIPEA_FORCE (1<<0) #define QUIRK_LVDS_SSC_DISABLE (1<<1) #define QUIRK_INVERT_BRIGHTNESS (1<<2) +#define QUIRK_NO_PCH_PWM_ENABLE (1<<3)

struct intel_fbdev; struct intel_fbc_work; diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c index 85f3eb7..42e207e 100644 --- a/drivers/gpu/drm/i915/intel_display.c +++ b/drivers/gpu/drm/i915/intel_display.c @@ -9398,6 +9398,17 @@ static void quirk_invert_brightness(struct drm_device *dev) DRM_INFO("applying inverted panel brightness quirk\n"); }

+/*

• • Some machines (Dell XPS13) suffer broken backlight controls if
• • BLM_PCH_PWM_ENABLE is set.
• */

+static void quirk_no_pcm_pwm_enable(struct drm_device *dev) +{

• struct drm_i915_private *dev_priv = dev->dev_private;
• dev_priv->quirks |= QUIRK_NO_PCH_PWM_ENABLE;
• DRM_INFO("applying no-PCH_PWM_ENABLE quirk\n");

+}

struct intel_quirk { int device; int subsystem_vendor; @@ -9467,6 +9478,11 @@ static struct intel_quirk intel_quirks[] = {

/* Acer Aspire 4736Z */ { 0x2a42, 0x1025, 0x0260, quirk_invert_brightness },

• /* Dell XPS13 HD Sandy Bridge */
• { 0x0116, 0x1028, 0x052e, quirk_no_pcm_pwm_enable },
• /* Dell XPS13 HD and XPS13 FHD Ivy Bridge */
• { 0x0166, 0x1028, 0x058b, quirk_no_pcm_pwm_enable },

};

static void intel_init_quirks(struct drm_device *dev) diff --git a/drivers/gpu/drm/i915/intel_panel.c b/drivers/gpu/drm/i915/intel_panel.c index 80bea1d..01b5a51 100644 --- a/drivers/gpu/drm/i915/intel_panel.c +++ b/drivers/gpu/drm/i915/intel_panel.c @@ -580,7 +580,8 @@ void intel_panel_enable_backlight(struct drm_device *dev, POSTING_READ(reg); I915_WRITE(reg, tmp | BLM_PWM_ENABLE);

• if (HAS_PCH_SPLIT(dev)) {
  

• if (HAS_PCH_SPLIT(dev) &&
  

•     !(dev_priv->quirks & QUIRK_NO_PCH_PWM_ENABLE)) {
  tmp = I915_READ(BLC_PWM_PCH_CTL1);
  tmp |= BLM_PCH_PWM_ENABLE;
  tmp &= ~BLM_PCH_OVERRIDE_ENABLE;
  

-- 1.8.1.2