[Intel-gfx] [PATCH] drm/i915 : Restore PWM_GRANULARITY after resume

[Jani Nikula]

On Mon, 19 Sep 2016, "Lee, Shawn C" <shawn.c.lee at intel.com> wrote:
> From: "Lee, Shawn C" <shawn.c.lee at intel.com>
>
> SPT_PWM_GRANULARITY (SOUTH_CHICKEN1, bit 0) controls the granularity
> (minimum increment) of the PWM backlight control counter. PWM frequency
> adjustment on 128 clock increments when this bit was 1. And 16 clock
> increments when it was 0.
>
> PWM frequency multiple octuple (from 200Hz to 1.6KHz) due to
> SPT_PWM_GRANULARITY was clear to 0 after S3. This patch save
> SOUTH_CHICKEN1 register value before suspend. And will restore
> it after i915 resume.
>
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=97486

Shawn, I already updated the patch. Perhaps I jumped the gun but I was
expecting an update and didn't get one and wanted to move this forward.
That patch still has your authorship [1]. This one still has issues.

BR,
Jani.

[1] http://patchwork.freedesktop.org/patch/msgid/1474273457-31680-2-git-send-email-jani.nikula@intel.com

>
> Cc: Jani Nikula <jani.nikula at intel.com>
> Reviewed-by: Cooper Chiou <cooper.chiou at intel.com>
> Reviewed-by: Wei Shun Chen <wei.shun.chang at intel.com>
> Reviewed-by: Gary C Wang <gary.c.wang at intel.com>
> Signed-off-by: Shawn Lee <shawn.c.lee at intel.com>
> ---
>  drivers/gpu/drm/i915/intel_drv.h   |    1 +
>  drivers/gpu/drm/i915/intel_panel.c |   30 ++++++++++++++++++++++++++++--
>  2 files changed, 29 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
> index 570a7ca..c4bc690 100644
> --- a/drivers/gpu/drm/i915/intel_drv.h
> +++ b/drivers/gpu/drm/i915/intel_drv.h
> @@ -256,6 +256,7 @@ struct intel_panel {
>  		u32 level;
>  		u32 min;
>  		u32 max;
> +		bool pwm_alternate_increment;
>  		bool enabled;
>  		bool combination_mode;	/* gen 2/4 only */
>  		bool active_low_pwm;
> diff --git a/drivers/gpu/drm/i915/intel_panel.c b/drivers/gpu/drm/i915/intel_panel.c
> index c10e9b0..6f8469b 100644
> --- a/drivers/gpu/drm/i915/intel_panel.c
> +++ b/drivers/gpu/drm/i915/intel_panel.c
> @@ -841,7 +841,7 @@ static void lpt_enable_backlight(struct intel_connector *connector)
>  {
>  	struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
>  	struct intel_panel *panel = &connector->panel;
> -	u32 pch_ctl1, pch_ctl2;
> +	u32 pch_ctl1, pch_ctl2, mul;
>  
>  	pch_ctl1 = I915_READ(BLC_PWM_PCH_CTL1);
>  	if (pch_ctl1 & BLM_PCH_PWM_ENABLE) {
> @@ -867,6 +867,22 @@ static void lpt_enable_backlight(struct intel_connector *connector)
>  
>  	/* This won't stick until the above enable. */
>  	intel_panel_actually_set_backlight(connector, panel->backlight.level);
> +	
> +	if (HAS_PCH_LPT(dev_priv)) {
> +		mul = I915_READ(SOUTH_CHICKEN2);
> +		if (panel->backlight.pwm_alternate_increment)
> +			mul |= LPT_PWM_GRANULARITY;
> +		else
> +			mul &= ~LPT_PWM_GRANULARITY;
> +		I915_WRITE(SOUTH_CHICKEN2, mul);
> +	} else {
> +		mul = I915_READ(SOUTH_CHICKEN1);
> +		if (panel->backlight.pwm_alternate_increment)
> +			mul |= SPT_PWM_GRANULARITY;
> +		else
> +			mul &= ~SPT_PWM_GRANULARITY;
> +		I915_WRITE(SOUTH_CHICKEN1, mul);
> +	}
>  }
>  
>  static void pch_enable_backlight(struct intel_connector *connector)
> @@ -1413,7 +1429,7 @@ static int lpt_setup_backlight(struct intel_connector *connector, enum pipe unus
>  {
>  	struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
>  	struct intel_panel *panel = &connector->panel;
> -	u32 pch_ctl1, pch_ctl2, val;
> +	u32 pch_ctl1, pch_ctl2, val, mul;
>  
>  	pch_ctl1 = I915_READ(BLC_PWM_PCH_CTL1);
>  	panel->backlight.active_low_pwm = pch_ctl1 & BLM_PCH_POLARITY;
> @@ -1436,6 +1452,16 @@ static int lpt_setup_backlight(struct intel_connector *connector, enum pipe unus
>  
>  	panel->backlight.enabled = pch_ctl1 & BLM_PCH_PWM_ENABLE;
>  
> +	if (HAS_PCH_LPT(dev_priv))
> +		mul = I915_READ(SOUTH_CHICKEN2) & LPT_PWM_GRANULARITY;
> +	else
> +		mul = I915_READ(SOUTH_CHICKEN1) & SPT_PWM_GRANULARITY;
> +
> +	if ( mul )
> +		panel->backlight.pwm_alternate_increment = true;
> +	else
> +		panel->backlight.pwm_alternate_increment = false;
> +
>  	return 0;
>  }

-- 
Jani Nikula, Intel Open Source Technology Center