[Intel-gfx] [RFC 01/11] drm/i915: Convert intel_rc6_residency_us to ns

[Chris Wilson]

Quoting Tvrtko Ursulin (2017-09-11 16:25:49)
> From: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> 
> Will be used for exposing the PMU counters.
> 
> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> ---
>  drivers/gpu/drm/i915/i915_drv.h |  8 +++++++-
>  drivers/gpu/drm/i915/intel_pm.c | 23 +++++++++--------------
>  2 files changed, 16 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index d07d1109e784..dbd054e88ca2 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -4114,9 +4114,15 @@ void vlv_phy_reset_lanes(struct intel_encoder *encoder);
>  
>  int intel_gpu_freq(struct drm_i915_private *dev_priv, int val);
>  int intel_freq_opcode(struct drm_i915_private *dev_priv, int val);
> -u64 intel_rc6_residency_us(struct drm_i915_private *dev_priv,
> +u64 intel_rc6_residency_ns(struct drm_i915_private *dev_priv,
>                            const i915_reg_t reg);
>  
> +static inline u64 intel_rc6_residency_us(struct drm_i915_private *dev_priv,
> +                                        const i915_reg_t reg)
> +{
> +       return DIV_ROUND_UP_ULL(intel_rc6_residency_ns(dev_priv, reg), 1000);
> +}
> +
>  #define I915_READ8(reg)                dev_priv->uncore.funcs.mmio_readb(dev_priv, (reg), true)
>  #define I915_WRITE8(reg, val)  dev_priv->uncore.funcs.mmio_writeb(dev_priv, (reg), (val), true)
>  
> diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> index fa9055a4f790..60461f49936b 100644
> --- a/drivers/gpu/drm/i915/intel_pm.c
> +++ b/drivers/gpu/drm/i915/intel_pm.c
> @@ -9343,10 +9343,10 @@ static u64 vlv_residency_raw(struct drm_i915_private *dev_priv,
>         return lower | (u64)upper << 8;
>  }
>  
> -u64 intel_rc6_residency_us(struct drm_i915_private *dev_priv,
> +u64 intel_rc6_residency_ns(struct drm_i915_private *dev_priv,
>                            const i915_reg_t reg)
>  {
> -       u64 time_hw, units, div;
> +       u64 res;
>  
>         if (!intel_enable_rc6())
>                 return 0;
> @@ -9355,22 +9355,17 @@ u64 intel_rc6_residency_us(struct drm_i915_private *dev_priv,
>  
>         /* On VLV and CHV, residency time is in CZ units rather than 1.28us */
>         if (IS_VALLEYVIEW(dev_priv) || IS_CHERRYVIEW(dev_priv)) {
> -               units = 1000;
> -               div = dev_priv->czclk_freq;
> +               res = vlv_residency_raw(dev_priv, reg);
> +               res = DIV_ROUND_UP_ULL(res * 1000000, dev_priv->czclk_freq);
>  
> -               time_hw = vlv_residency_raw(dev_priv, reg);
> -       } else if (IS_GEN9_LP(dev_priv)) {
> -               units = 1000;
> -               div = 1200;             /* 833.33ns */
> -
> -               time_hw = I915_READ(reg);
>         } else {
> -               units = 128000; /* 1.28us */
> -               div = 100000;
> +               /* 833.33ns units on Gen9LP, 1.28us elsewhere. */
> +               unsigned int unit = IS_GEN9_LP(dev_priv) ? 833 : 1280;
>  
> -               time_hw = I915_READ(reg);
> +               res = (u64)I915_READ(reg) * unit;
>         }
>  
>         intel_runtime_pm_put(dev_priv);

I was worried that you were going to assume that we took a wakeref in
pmu, but I see that it keeps the if (intel_rpm_get_if_in_use() {}

Should we push the rpm wakeref to the caller? intel_runtime_pm_get()
isn't as simple as a single atomic op you would like it to be...
-Chris