Re: [PATCH 4/4] drm/i915: Add support for VLV GPLL bypass

[Jesse Barnes <jbarnes@virtuousgeek.org>]

On Tue,  5 Nov 2013 22:42:31 +0200
ville.syrjala@linux.intel.com wrote:

> From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> 
> Supposedly all current SKUs use GPLL, but there could be ones in the
> future that do not. Add (at least theoretical) support for such things.
> 
> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> ---
>  drivers/gpu/drm/i915/i915_drv.h |  1 +
>  drivers/gpu/drm/i915/intel_pm.c | 24 +++++++++++++++++++++++-
>  2 files changed, 24 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index dd40925..d9b4c26 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -876,6 +876,7 @@ struct intel_gen6_power_mgmt {
>  	enum { LOW_POWER, BETWEEN, HIGH_POWER } power;
>  
>  	bool enabled;
> +	bool gpll_enabled;
>  	struct delayed_work delayed_resume_work;
>  
>  	/*
> diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> index f5bb9b3..caec9fe 100644
> --- a/drivers/gpu/drm/i915/intel_pm.c
> +++ b/drivers/gpu/drm/i915/intel_pm.c
> @@ -4064,7 +4064,9 @@ static void valleyview_enable_rps(struct drm_device *dev)
>  
>  	val = vlv_punit_read(dev_priv, PUNIT_REG_GPU_FREQ_STS);
>  
> -	DRM_DEBUG_DRIVER("GPLL enabled? %s\n", val & 0x10 ? "yes" : "no");
> +	dev_priv->rps.gpll_enabled = val & 0x10;
> +	DRM_DEBUG_DRIVER("GPLL enabled? %s\n",
> +			 dev_priv->rps.gpll_enabled ? "yes" : "no");
>  	DRM_DEBUG_DRIVER("GPU status: 0x%08x\n", val);
>  
>  	dev_priv->rps.cur_delay = (val >> 8) & 0xff;
> @@ -5943,6 +5945,17 @@ int vlv_gpu_freq(struct drm_i915_private *dev_priv, int val)
>  {
>  	int div;
>  
> +	if (!dev_priv->rps.gpll_enabled) {
> +		int hpll_freq = valleyview_get_vco(dev_priv);
> +
> +		div = 0xee + (10 << 1) - val;
> +
> +		if (WARN_ON(div == 0))
> +			return -1;
> +
> +		return DIV_ROUND_CLOSEST(hpll_freq << 1, div);
> +	}
> +
>  	/* 4 x czclk */
>  	switch (dev_priv->mem_freq) {
>  	case 800:
> @@ -5965,6 +5978,15 @@ int vlv_freq_opcode(struct drm_i915_private *dev_priv, int val)
>  {
>  	int mul;
>  
> +	if (!dev_priv->rps.gpll_enabled) {
> +		int hpll_freq = valleyview_get_vco(dev_priv);
> +
> +		if (WARN_ON(val == 0))
> +			return -1;
> +
> +		return 0xee + (10 << 1) - DIV_ROUND_CLOSEST(hpll_freq << 1, val);
> +	}
> +
>  	/* 4 x czclk */
>  	switch (dev_priv->mem_freq) {
>  	case 800:

I don't think we want to add this; even though it's a small amount of
code it's totally unnecessary on real hw, and will probably just bit
rot.

-- 
Jesse Barnes, Intel Open Source Technology Center
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