Re: [PATCH 1/3] drm/i915: Use GPLL ref clock to calculate GPU freqs on VLV/CHV

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

On Wed, Mar 16, 2016 at 07:17:51PM +0200, Imre Deak wrote:
> On Fri, 2016-03-04 at 21:43 +0200, ville.syrjala@linux.intel.com wrote:
> > From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > 
> > Extract the GPLL reference frequency from CCK and use it in the
> > GPU freq<->opcode conversions on VLV/CHV. This eliminates all the
> > assumptions we have about which divider is used for which czclk
> > frequency.
> > 
> > Note that unlike most clocks from CCK, the GPLL ref clock is a divided
> > down version of the CZ clock rather than the HPLL clock. CZ clock itself
> > is a divided down version of the HPLL clock though, so in effect it just
> > gets divided down twice.
> > 
> > While at it, throw in a few comments explaining the remaining constants
> > for anyone who later wants to compare this to the spreadsheets.
> > 
> > Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> 
> Looks ok. The relevant info is spread across multiple documents but
> based on what I gathered this is ok and the old and new way of
> calculation matches, so:
> Reviewed-by: Imre Deak <imre.deak@intel.com>
> 
> Some notes:
> For clarity, I'd rename *_gpu_freq to *_gpu_opcode_to_freq and
> *_freq_opcode to *_gpu_freq_to_opcode and mention that the CHV CU/CU2X
> clocks are also known as slow/fast clock, so it better matches the VLV
> code.

Well I think the slow/fast names might be more of a leftover from VLV,
ie. someone just forgot to update the names in bunch of the docs for
CHV. But adding a note might be prudent to avoid people having to
wonder about it.

> 
> The entries for VLV 320/400MHz CZ clock are missing from the tables
> that I saw, which is one justification for this change, since we don't
> know if vlv_gpu_freq_div() was correct.

I don't think VLV had 320 or 400 SKUs.

> 
> --Imre
> 
> 
> 
> > ---
> >  drivers/gpu/drm/i915/i915_drv.h      |  1 +
> >  drivers/gpu/drm/i915/i915_reg.h      |  1 +
> >  drivers/gpu/drm/i915/intel_display.c | 19 ++++++---
> >  drivers/gpu/drm/i915/intel_drv.h     |  2 +
> >  drivers/gpu/drm/i915/intel_pm.c      | 74 +++++++++++++-----------------------
> >  5 files changed, 44 insertions(+), 53 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> > index f37ac120a29d..95f77cd0ce17 100644
> > --- a/drivers/gpu/drm/i915/i915_drv.h
> > +++ b/drivers/gpu/drm/i915/i915_drv.h
> > @@ -1166,6 +1166,7 @@ struct intel_gen6_power_mgmt {
> >  	u8 efficient_freq;	/* AKA RPe. Pre-determined balanced frequency */
> >  	u8 rp1_freq;		/* "less than" RP0 power/freqency */
> >  	u8 rp0_freq;		/* Non-overclocked max frequency. */
> > +	u16 gpll_ref_freq;	/* vlv/chv GPLL reference frequency */
> >  
> >  	u8 up_threshold; /* Current %busy required to uplock */
> >  	u8 down_threshold; /* Current %busy required to downclock */
> > diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> > index 7dfc4007f3fa..aa21bfc06a24 100644
> > --- a/drivers/gpu/drm/i915/i915_reg.h
> > +++ b/drivers/gpu/drm/i915/i915_reg.h
> > @@ -785,6 +785,7 @@ enum skl_disp_power_wells {
> >  #define  DSI_PLL_M1_DIV_SHIFT			0
> >  #define  DSI_PLL_M1_DIV_MASK			(0x1ff << 0)
> >  #define CCK_CZ_CLOCK_CONTROL			0x62
> > +#define CCK_GPLL_CLOCK_CONTROL			0x67
> >  #define CCK_DISPLAY_CLOCK_CONTROL		0x6b
> >  #define CCK_DISPLAY_REF_CLOCK_CONTROL		0x6c
> >  #define  CCK_TRUNK_FORCE_ON			(1 << 17)
> > diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> > index 62d36a7b3398..ba50de534f9a 100644
> > --- a/drivers/gpu/drm/i915/intel_display.c
> > +++ b/drivers/gpu/drm/i915/intel_display.c
> > @@ -147,15 +147,12 @@ static int valleyview_get_vco(struct drm_i915_private *dev_priv)
> >  	return vco_freq[hpll_freq] * 1000;
> >  }
> >  
> > -static int vlv_get_cck_clock_hpll(struct drm_i915_private *dev_priv,
> > -				  const char *name, u32 reg)
> > +int vlv_get_cck_clock(struct drm_i915_private *dev_priv,
> > +		      const char *name, u32 reg, int ref_freq)
> >  {
> >  	u32 val;
> >  	int divider;
> >  
> > -	if (dev_priv->hpll_freq == 0)
> > -		dev_priv->hpll_freq = valleyview_get_vco(dev_priv);
> > -
> >  	mutex_lock(&dev_priv->sb_lock);
> >  	val = vlv_cck_read(dev_priv, reg);
> >  	mutex_unlock(&dev_priv->sb_lock);
> > @@ -166,7 +163,17 @@ static int vlv_get_cck_clock_hpll(struct drm_i915_private *dev_priv,
> >  	     (divider << CCK_FREQUENCY_STATUS_SHIFT),
> >  	     "%s change in progress\n", name);
> >  
> > -	return DIV_ROUND_CLOSEST(dev_priv->hpll_freq << 1, divider + 1);
> > +	return DIV_ROUND_CLOSEST(ref_freq << 1, divider + 1);
> > +}
> > +
> > +static int vlv_get_cck_clock_hpll(struct drm_i915_private *dev_priv,
> > +				  const char *name, u32 reg)
> > +{
> > +	if (dev_priv->hpll_freq == 0)
> > +		dev_priv->hpll_freq = valleyview_get_vco(dev_priv);
> > +
> > +	return vlv_get_cck_clock(dev_priv, name, reg,
> > +				 dev_priv->hpll_freq);
> >  }
> >  
> >  static int
> > diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
> > index cd0b4eacbddf..c416f0adae48 100644
> > --- a/drivers/gpu/drm/i915/intel_drv.h
> > +++ b/drivers/gpu/drm/i915/intel_drv.h
> > @@ -1116,6 +1116,8 @@ void i915_audio_component_init(struct drm_i915_private *dev_priv);
> >  void i915_audio_component_cleanup(struct drm_i915_private *dev_priv);
> >  
> >  /* intel_display.c */
> > +int vlv_get_cck_clock(struct drm_i915_private *dev_priv,
> > +		      const char *name, u32 reg, int ref_freq);
> >  extern const struct drm_plane_funcs intel_plane_funcs;
> >  unsigned int intel_rotation_info_size(const struct intel_rotation_info *rot_info);
> >  bool intel_has_pending_fb_unpin(struct drm_device *dev);
> > diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> > index f65e84137060..c53b8c4d381c 100644
> > --- a/drivers/gpu/drm/i915/intel_pm.c
> > +++ b/drivers/gpu/drm/i915/intel_pm.c
> > @@ -5364,6 +5364,17 @@ static void valleyview_cleanup_pctx(struct drm_device *dev)
> >  	dev_priv->vlv_pctx = NULL;
> >  }
> >  
> > +static void vlv_init_gpll_ref_freq(struct drm_i915_private *dev_priv)
> > +{
> > +	dev_priv->rps.gpll_ref_freq =
> > +		vlv_get_cck_clock(dev_priv, "GPLL ref",
> > +				  CCK_GPLL_CLOCK_CONTROL,
> > +				  dev_priv->czclk_freq);
> > +
> > +	DRM_DEBUG_DRIVER("GPLL reference freq: %d kHz\n",
> > +			 dev_priv->rps.gpll_ref_freq);
> > +}
> > +
> >  static void valleyview_init_gt_powersave(struct drm_device *dev)
> >  {
> >  	struct drm_i915_private *dev_priv = dev->dev_private;
> > @@ -5371,6 +5382,8 @@ static void valleyview_init_gt_powersave(struct drm_device *dev)
> >  
> >  	valleyview_setup_pctx(dev);
> >  
> > +	vlv_init_gpll_ref_freq(dev_priv);
> > +
> >  	mutex_lock(&dev_priv->rps.hw_lock);
> >  
> >  	val = vlv_punit_read(dev_priv, PUNIT_REG_GPU_FREQ_STS);
> > @@ -5428,6 +5441,8 @@ static void cherryview_init_gt_powersave(struct drm_device *dev)
> >  
> >  	cherryview_setup_pctx(dev);
> >  
> > +	vlv_init_gpll_ref_freq(dev_priv);
> > +
> >  	mutex_lock(&dev_priv->rps.hw_lock);
> >  
> >  	mutex_lock(&dev_priv->sb_lock);
> > @@ -7261,68 +7276,33 @@ int sandybridge_pcode_write(struct drm_i915_private *dev_priv, u32 mbox, u32 val
> >  	return 0;
> >  }
> >  
> > -static int vlv_gpu_freq_div(unsigned int czclk_freq)
> > -{
> > -	switch (czclk_freq) {
> > -	case 200:
> > -		return 10;
> > -	case 267:
> > -		return 12;
> > -	case 320:
> > -	case 333:
> > -		return 16;
> > -	case 400:
> > -		return 20;
> > -	default:
> > -		return -1;
> > -	}
> > -}
> > -
> >  static int byt_gpu_freq(struct drm_i915_private *dev_priv, int val)
> >  {
> > -	int div, czclk_freq = DIV_ROUND_CLOSEST(dev_priv->czclk_freq, 1000);
> > -
> > -	div = vlv_gpu_freq_div(czclk_freq);
> > -	if (div < 0)
> > -		return div;
> > -
> > -	return DIV_ROUND_CLOSEST(czclk_freq * (val + 6 - 0xbd), div);
> > +	/*
> > +	 * N = val - 0xb7
> > +	 * Slow = Fast = GPLL ref * N
> > +	 */
> > +	return DIV_ROUND_CLOSEST(dev_priv->rps.gpll_ref_freq * (val - 0xb7), 1000);
> >  }
> >  
> >  static int byt_freq_opcode(struct drm_i915_private *dev_priv, int val)
> >  {
> > -	int mul, czclk_freq = DIV_ROUND_CLOSEST(dev_priv->czclk_freq, 1000);
> > -
> > -	mul = vlv_gpu_freq_div(czclk_freq);
> > -	if (mul < 0)
> > -		return mul;
> > -
> > -	return DIV_ROUND_CLOSEST(mul * val, czclk_freq) + 0xbd - 6;
> > +	return DIV_ROUND_CLOSEST(1000 * val, dev_priv->rps.gpll_ref_freq) + 0xb7;
> >  }
> >  
> >  static int chv_gpu_freq(struct drm_i915_private *dev_priv, int val)
> >  {
> > -	int div, czclk_freq = DIV_ROUND_CLOSEST(dev_priv->czclk_freq, 1000);
> > -
> > -	div = vlv_gpu_freq_div(czclk_freq);
> > -	if (div < 0)
> > -		return div;
> > -	div /= 2;
> > -
> > -	return DIV_ROUND_CLOSEST(czclk_freq * val, 2 * div) / 2;
> > +	/*
> > +	 * N = val / 2
> > +	 * CU = CU2x / 2 = GPLL ref * N / 2
> > +	 */
> > +	return DIV_ROUND_CLOSEST(dev_priv->rps.gpll_ref_freq * val, 2 * 2 * 1000);
> >  }
> >  
> >  static int chv_freq_opcode(struct drm_i915_private *dev_priv, int val)
> >  {
> > -	int mul, czclk_freq = DIV_ROUND_CLOSEST(dev_priv->czclk_freq, 1000);
> > -
> > -	mul = vlv_gpu_freq_div(czclk_freq);
> > -	if (mul < 0)
> > -		return mul;
> > -	mul /= 2;
> > -
> >  	/* CHV needs even values */
> > -	return DIV_ROUND_CLOSEST(val * 2 * mul, czclk_freq) * 2;
> > +	return DIV_ROUND_CLOSEST(2 * 1000 * val, dev_priv->rps.gpll_ref_freq) * 2;
> >  }
> >  
> >  int intel_gpu_freq(struct drm_i915_private *dev_priv, int val)

-- 
Ville Syrjälä
Intel OTC
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