On Mon, 19 Sep 2016, "Lee, Shawn C" <shawn.c....@intel.com> wrote:
> PWM was enabled in bios. i915 driver will save max duty to 
> panel->backlight.max.
> So *_hz_to_pwm will not be called if backlight.max not zero. 

And what difference does it make?

BR,
Jani.

>
>       pch_ctl2 = I915_READ(BLC_PWM_PCH_CTL2);
>       panel->backlight.max = pch_ctl2 >> 16;
>
>       if (!panel->backlight.max)
>               panel->backlight.max = get_backlight_max_vbt(connector);
>
> -----Original Message-----
> From: Nikula, Jani 
> Sent: Monday, September 19, 2016 4:24 PM
> To: intel-gfx@lists.freedesktop.org
> Cc: Nikula, Jani <jani.nik...@intel.com>; Lee, Shawn C <shawn.c....@intel.com>
> Subject: [PATCH v2 1/2] drm/i915/backlight: setup and cache pwm alternate 
> increment value
>
> This will also be needed later on when setting up the alternate increment in 
> backlight enable.
>
> Cc: Shawn Lee <shawn.c....@intel.com>
> Signed-off-by: Jani Nikula <jani.nik...@intel.com>
> ---
>  drivers/gpu/drm/i915/intel_drv.h   |  1 +
>  drivers/gpu/drm/i915/intel_panel.c | 14 +++++++++++---
>  2 files changed, 12 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_drv.h 
> b/drivers/gpu/drm/i915/intel_drv.h
> index 8fd16adf069b..c3e65e515c9d 100644
> --- a/drivers/gpu/drm/i915/intel_drv.h
> +++ b/drivers/gpu/drm/i915/intel_drv.h
> @@ -263,6 +263,7 @@ struct intel_panel {
>               bool enabled;
>               bool combination_mode;  /* gen 2/4 only */
>               bool active_low_pwm;
> +             bool alternate_pwm_increment;   /* lpt+ */
>  
>               /* PWM chip */
>               bool util_pin_active_low;       /* bxt+ */
> diff --git a/drivers/gpu/drm/i915/intel_panel.c 
> b/drivers/gpu/drm/i915/intel_panel.c
> index c10e9b0405e8..8bc43205d6a0 100644
> --- a/drivers/gpu/drm/i915/intel_panel.c
> +++ b/drivers/gpu/drm/i915/intel_panel.c
> @@ -1242,10 +1242,10 @@ static u32 bxt_hz_to_pwm(struct intel_connector 
> *connector, u32 pwm_freq_hz)
>   */
>  static u32 spt_hz_to_pwm(struct intel_connector *connector, u32 pwm_freq_hz) 
>  {
> -     struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
> +     struct intel_panel *panel = &connector->panel;
>       u32 mul;
>  
> -     if (I915_READ(SOUTH_CHICKEN1) & SPT_PWM_GRANULARITY)
> +     if (panel->backlight.alternate_pwm_increment)
>               mul = 128;
>       else
>               mul = 16;
> @@ -1261,9 +1261,10 @@ static u32 spt_hz_to_pwm(struct intel_connector 
> *connector, u32 pwm_freq_hz)  static u32 lpt_hz_to_pwm(struct intel_connector 
> *connector, u32 pwm_freq_hz)  {
>       struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
> +     struct intel_panel *panel = &connector->panel;
>       u32 mul, clock;
>  
> -     if (I915_READ(SOUTH_CHICKEN2) & LPT_PWM_GRANULARITY)
> +     if (panel->backlight.alternate_pwm_increment)
>               mul = 16;
>       else
>               mul = 128;
> @@ -1414,6 +1415,13 @@ 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;
> +     bool alt;
> +
> +     if (HAS_PCH_LPT(dev_priv))
> +             alt = I915_READ(SOUTH_CHICKEN2) & LPT_PWM_GRANULARITY;
> +     else
> +             alt = I915_READ(SOUTH_CHICKEN1) & SPT_PWM_GRANULARITY;
> +     panel->backlight.alternate_pwm_increment = alt;
>  
>       pch_ctl1 = I915_READ(BLC_PWM_PCH_CTL1);
>       panel->backlight.active_low_pwm = pch_ctl1 & BLM_PCH_POLARITY;
> --
> 2.1.4
>

-- 
Jani Nikula, Intel Open Source Technology Center
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