Re: [RFC 01/11] drm/i915: Convert intel_rc6_residency_us to ns

Chris Wilson
2017-09-14T19:49:28Z

Quoting Tvrtko Ursulin (2017-09-11 16:25:49)
> From: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
>
> Will be used for exposing the PMU counters.
>
> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@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