[Intel-gfx] [PATCH] drm/i915: Add the ddi get cdclk code for BXT (v3)

[Ville Syrjälä]

On Tue, Jun 23, 2015 at 02:14:26PM -0700, Bob Paauwe wrote:
> The registers and process differ from other platforms. If the hardware
> was programmed incorrectly, this will return invalid cdclk values, which
> should then cause reprogramming of the hardware.
> 
> v2(Matt): Return 19.2 MHz when DE PLL is disabled (Ville)
> v3: Make less assumptions about the hardware state (Ville)
> 
> Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
> Cc: Imre Deak <imre.deak at intel.com>
> Cc: Matt Roper <matthew.d.roper at intel.com>
> Signed-off-by: Bob Paauwe <bob.j.paauwe at intel.com>
> Signed-off-by: Matt Roper <matthew.d.roper at intel.com>

Reviewed-by: Ville Syrjälä <ville.syrjala at linux.intel.com>

> ---
>  drivers/gpu/drm/i915/intel_display.c | 31 +++++++++++++++++++++++++++++++
>  1 file changed, 31 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index c38c297..201826e 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -6687,6 +6687,34 @@ static int skylake_get_display_clock_speed(struct drm_device *dev)
>  	return 24000;
>  }
>  
> +static int broxton_get_display_clock_speed(struct drm_device *dev)
> +{
> +	struct drm_i915_private *dev_priv = to_i915(dev);
> +	uint32_t cdctl = I915_READ(CDCLK_CTL);
> +	uint32_t pll_ratio = I915_READ(BXT_DE_PLL_CTL) & BXT_DE_PLL_RATIO_MASK;
> +	uint32_t pll_enab = I915_READ(BXT_DE_PLL_ENABLE);
> +	int cdclk;
> +
> +	if (!(pll_enab & BXT_DE_PLL_PLL_ENABLE))
> +		return 19200;
> +
> +	cdclk = 19200 * pll_ratio / 2;
> +
> +	switch (cdctl & BXT_CDCLK_CD2X_DIV_SEL_MASK) {
> +	case BXT_CDCLK_CD2X_DIV_SEL_1:
> +		return cdclk;  /* 576MHz or 624MHz */
> +	case BXT_CDCLK_CD2X_DIV_SEL_1_5:
> +		return cdclk * 2 / 3; /* 384MHz */
> +	case BXT_CDCLK_CD2X_DIV_SEL_2:
> +		return cdclk / 2; /* 288MHz */
> +	case BXT_CDCLK_CD2X_DIV_SEL_4:
> +		return cdclk / 4; /* 144MHz */
> +	}
> +
> +	/* error case, do as if DE PLL isn't enabled */
> +	return 19200;
> +}
> +
>  static int broadwell_get_display_clock_speed(struct drm_device *dev)
>  {
>  	struct drm_i915_private *dev_priv = dev->dev_private;
> @@ -14649,6 +14677,9 @@ static void intel_init_display(struct drm_device *dev)
>  	if (IS_SKYLAKE(dev))
>  		dev_priv->display.get_display_clock_speed =
>  			skylake_get_display_clock_speed;
> +	else if (IS_BROXTON(dev))
> +		dev_priv->display.get_display_clock_speed =
> +			broxton_get_display_clock_speed;
>  	else if (IS_BROADWELL(dev))
>  		dev_priv->display.get_display_clock_speed =
>  			broadwell_get_display_clock_speed;
> -- 
> 2.1.0

-- 
Ville Syrjälä
Intel OTC