[Intel-gfx] [PATCH 28/67] drm/i915/cnl: Implement .get_display_clock_speed() for CNL

[Imre Deak]

On Thu, Apr 06, 2017 at 12:15:24PM -0700, Rodrigo Vivi wrote:
> From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> 
> Add support for reading out the cdclk frequency from the hardware on
> CNL. Very similar to BXT, with a few new twists and turns:
> * the PLL is now called CDCLK PLL, not DE PLL
> * reference clock can be 24 MHz in addition to the 19.2 MHz BXT had
> * the ratio now lives in the PLL enable register
> * Only 1x and 2x CD2X dividers are supported
> 
> v2: Deal with PLL lock bit the same way as BXT/SKL do now
> v3: DSSM refclk indicator is bit 31 not 24 (Ander)
> v4: Rebased by Rodrigo after Ville's cdclk rework.
> 
> Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
> Signed-off-by: Rodrigo Vivi <rodrigo.vivi at intel.com>
> ---
>  drivers/gpu/drm/i915/i915_reg.h    |  5 ++++
>  drivers/gpu/drm/i915/intel_cdclk.c | 54 +++++++++++++++++++++++++++++++++++++-
>  2 files changed, 58 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> index ac8a223..8353892 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -6557,6 +6557,9 @@ enum {
>  #define SKL_DFSM_PIPE_B_DISABLE		(1 << 21)
>  #define SKL_DFSM_PIPE_C_DISABLE		(1 << 28)
>  
> +#define SKL_DSSM			_MMIO(0x51004)
> +#define CNL_DSSM_CDCLK_PLL_REFCLK_24MHz	(1 << 31)
> +
>  #define GEN7_FF_SLICE_CS_CHICKEN1	_MMIO(0x20e0)
>  #define   GEN9_FFSC_PERCTX_PREEMPT_CTRL	(1<<14)
>  
> @@ -8130,6 +8133,8 @@ enum {
>  #define BXT_DE_PLL_ENABLE		_MMIO(0x46070)
>  #define   BXT_DE_PLL_PLL_ENABLE		(1 << 31)
>  #define   BXT_DE_PLL_LOCK		(1 << 30)
> +#define   CNL_CDCLK_PLL_RATIO(x)	(x)	/* {28,44} * 19.2 or 24MHz */

Nit: 35,55 are also valid for 19.2MHz.

> +#define   CNL_CDCLK_PLL_RATIO_MASK	0xff
>  
>  /* GEN9 DC */
>  #define DC_STATE_EN			_MMIO(0x45504)
> diff --git a/drivers/gpu/drm/i915/intel_cdclk.c b/drivers/gpu/drm/i915/intel_cdclk.c
> index 4745596..a4e2bd5 100644
> --- a/drivers/gpu/drm/i915/intel_cdclk.c
> +++ b/drivers/gpu/drm/i915/intel_cdclk.c
> @@ -1400,6 +1400,56 @@ void bxt_uninit_cdclk(struct drm_i915_private *dev_priv)
>  	bxt_set_cdclk(dev_priv, &cdclk_state);
>  }
>  
> +static void cnl_cdclk_pll_update(struct drm_i915_private *dev_priv,
> +				 struct intel_cdclk_state *cdclk_state)
> +{
> +	u32 val;
> +
> +	if (I915_READ(SKL_DSSM) & CNL_DSSM_CDCLK_PLL_REFCLK_24MHz)
> +		cdclk_state->ref = 24000;
> +	else
> +		cdclk_state->ref = 19200;
> +
> +	cdclk_state->vco = 0;
> +
> +	val = I915_READ(BXT_DE_PLL_ENABLE);
> +	if ((val & BXT_DE_PLL_PLL_ENABLE) == 0)
> +		return;
> +
> +	if (WARN_ON((val & BXT_DE_PLL_LOCK) == 0))
> +		return;
> +
> +	cdclk_state->vco = (val & CNL_CDCLK_PLL_RATIO_MASK) * cdclk_state->ref;
> +}
> +
> +static void cnl_get_cdclk(struct drm_i915_private *dev_priv,
> +			 struct intel_cdclk_state *cdclk_state)
> +{
> +	u32 divider;
> +	int div;
> +
> +	cnl_cdclk_pll_update(dev_priv, cdclk_state);

The other platforms set cdclk to the ref clock here, not sure
if it's ok to leave it uninited. With that change it looks ok:

Reviewed-by: Imre Deak <imre.deak at intel.com>

> +
> +	if (cdclk_state->vco == 0)
> +		return;
> +
> +	divider = I915_READ(CDCLK_CTL) & BXT_CDCLK_CD2X_DIV_SEL_MASK;
> +
> +	switch (divider) {
> +	case BXT_CDCLK_CD2X_DIV_SEL_1:
> +		div = 2;
> +		break;
> +	case BXT_CDCLK_CD2X_DIV_SEL_2:
> +		div = 4;
> +		break;
> +	default:
> +		MISSING_CASE(divider);
> +		return;
> +	}
> +
> +	cdclk_state->cdclk = DIV_ROUND_CLOSEST(cdclk_state->vco, div);
> +}
> +
>  /**
>   * intel_cdclk_state_compare - Determine if two CDCLK states differ
>   * @a: first CDCLK state
> @@ -1897,7 +1947,9 @@ void intel_init_cdclk_hooks(struct drm_i915_private *dev_priv)
>  			skl_modeset_calc_cdclk;
>  	}
>  
> -	if (IS_GEN9_BC(dev_priv))
> +	if (IS_CANNONLAKE(dev_priv))
> +		dev_priv->display.get_cdclk = cnl_get_cdclk;
> +	else if (IS_GEN9_BC(dev_priv))
>  		dev_priv->display.get_cdclk = skl_get_cdclk;
>  	else if (IS_GEN9_LP(dev_priv))
>  		dev_priv->display.get_cdclk = bxt_get_cdclk;
> -- 
> 1.9.1
> 
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