Re: [PATCH 1/2] drm/i915: Get CZ clock for VLV

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Mon, Aug 04, 2014 at 10:44:04PM +0530, Vandana Kannan wrote:
> CZ clock is related to data flow from memory to display plane. This is
> required for comparison with CD clock before programming PFI credits.
> 
> Signed-off-by: Vandana Kannan <vandana.kannan@intel.com>
> ---
>  drivers/gpu/drm/i915/i915_drv.h      |  2 ++
>  drivers/gpu/drm/i915/i915_reg.h      |  1 +
>  drivers/gpu/drm/i915/intel_display.c | 20 ++++++++++++++++++++
>  3 files changed, 23 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index 174a294..baeb56f 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -2764,6 +2764,8 @@ void vlv_flisdsi_write(struct drm_i915_private *dev_priv, u32 reg, u32 val);
>  int vlv_gpu_freq(struct drm_i915_private *dev_priv, int val);
>  int vlv_freq_opcode(struct drm_i915_private *dev_priv, int val);
>  
> +int valleyview_get_cz_clock_speed(struct drm_device *dev);
> +
>  #define FORCEWAKE_RENDER	(1 << 0)
>  #define FORCEWAKE_MEDIA		(1 << 1)
>  #define FORCEWAKE_ALL		(FORCEWAKE_RENDER | FORCEWAKE_MEDIA)
> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> index fe5c276..1b8f095 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -601,6 +601,7 @@ enum punit_power_well {
>  #define  DISPLAY_FREQUENCY_STATUS		(0x1f << 8)
>  #define  DISPLAY_FREQUENCY_STATUS_SHIFT		8
>  #define  DISPLAY_FREQUENCY_VALUES		(0x1f << 0)
> +#define CCK_CZ_CONTROL				0x62

Please move the reg define to just above DISPLAY_CLOCK_CONTROL to keep
things in neat order.

Also it might be a good idea to rename the DISPLAY_TRUNK_* and
DISPLAY_FREQUENCY_* bits to CCK_... instead of DISPLAY_... to make
it clear they apply to all CCK clock control registers.

>  
>  /**
>   * DOC: DPIO
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index 99eb7ca..56a8090 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -5278,6 +5278,26 @@ static int valleyview_get_display_clock_speed(struct drm_device *dev)
>  	return DIV_ROUND_CLOSEST(vco << 1, divider + 1);
>  }
>  
> +int valleyview_get_cz_clock_speed(struct drm_device *dev)
> +{
> +	struct drm_i915_private *dev_priv = dev->dev_private;
> +	int vco = valleyview_get_vco(dev_priv);
> +	u32 val;
> +	int divider;
> +
> +	mutex_lock(&dev_priv->dpio_lock);
> +	val = vlv_cck_read(dev_priv, CCK_CZ_CONTROL);
> +	mutex_unlock(&dev_priv->dpio_lock);
> +
> +	divider = val & DISPLAY_FREQUENCY_VALUES;
> +
> +	WARN((val & DISPLAY_FREQUENCY_STATUS) !=
> +	     (divider << DISPLAY_FREQUENCY_STATUS_SHIFT),
> +	     "czclk change in progress\n");
> +
> +	return DIV_ROUND_CLOSEST(vco << 1, divider + 1);
> +}

We might want to refactor this a bit. Eg.:

static int valleyview_get_cck_clock_speed(u32 reg, const char *name)
{
  ... do the cck read etc. from CCK clock control register 'reg'
}

static int valleyview_get_cz_clock_speed()
{
	return valleyview_get_cck_clock_speed(CCK_CZ_CLOCK_CONTROL, "czclk");
}

static int valleyview_get_display_clock_speed()
{
	...
	return valleyview_get_cck_clock_speed(CCK_DISPLAY_CLOCK_CONTROL, "cdclk");
}

> +
>  static int i945_get_display_clock_speed(struct drm_device *dev)
>  {
>  	return 400000;
> -- 
> 2.0.1
> 
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-- 
Ville Syrjälä
Intel OTC