[PATCH backport to 3.5.y] drm/i915: quirk no PCH_PWM_ENABLE for Dell XPS13 backlight

[Luis Henriques]

Kamal Mostafa <kamal at canonical.com> writes:

> Hi Luis-
>
> Please consider this backport for 3.5.y-stable.  Thanks,
>
>  -Kamal

Thanks Kamal, I'll queue it for the 3.5 kernel.  The reason I had
dropped it initially was that it was tagged to stable v3.8+.

Cheers,
-- 
Luis


>
> ---------- >8 ----------
> commit e85843bec6c2ea7c10ec61238396891cc2b753a9 upstream.
>
> 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 at gmail.com>
> Tested-by: Kent Baxley <kent.baxley at canonical.com>
> Signed-off-by: Kamal Mostafa <kamal at canonical.com>
> Signed-off-by: Daniel Vetter <daniel.vetter at ffwll.ch>
> [ kamal: backport to 3.5 ]
> ---
>  drivers/gpu/drm/i915/i915_drv.h      |  1 +
>  drivers/gpu/drm/i915/intel_display.c | 16 ++++++++++++++++
>  drivers/gpu/drm/i915/intel_lvds.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 d85db22..bb95eda 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -329,6 +329,7 @@ enum intel_pch {
>  #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 290d89d..05f75ff 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -6874,6 +6874,17 @@ 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;
> @@ -6949,6 +6960,11 @@ static struct intel_quirk intel_quirks[] = {
>  
>  	/* Acer/Packard Bell NCL20 */
>  	{ 0x2a42, 0x1025, 0x034b, 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_lvds.c b/drivers/gpu/drm/i915/intel_lvds.c
> index d18c49a..440ed88 100644
> --- a/drivers/gpu/drm/i915/intel_lvds.c
> +++ b/drivers/gpu/drm/i915/intel_lvds.c
> @@ -1097,7 +1097,8 @@ bool intel_lvds_init(struct drm_device *dev)
>  		goto failed;
>  
>  out:
> -	if (HAS_PCH_SPLIT(dev)) {
> +	if (HAS_PCH_SPLIT(dev) &&
> +	    !(dev_priv->quirks & QUIRK_NO_PCH_PWM_ENABLE)) {
>  		u32 pwm;
>  
>  		pipe = (I915_READ(PCH_LVDS) & LVDS_PIPEB_SELECT) ? 1 : 0;