[Intel-gfx] [PATCH] drm/i915: Save/restore irq state for vlv_residency_raw()

[Tvrtko Ursulin]

On 22/11/2017 22:25, Chris Wilson wrote:
> Since commit 6060b6aec03c ("drm/i915/pmu: Add RC6 residency metrics"),
> vlv_residency_raw() may be called from an irq-disabled context (via perf
> event sampling on remote cpu). As such, we can no longer assume that we
> are called from process context and must save/restore the irq state for
> the spinlock.
> 
> Fixes: 6060b6aec03c ("drm/i915/pmu: Add RC6 residency metrics")
> Testcase: igt/perf_pmu/other-init-3
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Chris Wilson <chris at chris-wilson.co.uk>
> ---
>   drivers/gpu/drm/i915/intel_pm.c | 6 +++---
>   1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> index 7d41aad79166..03d67d8ab647 100644
> --- a/drivers/gpu/drm/i915/intel_pm.c
> +++ b/drivers/gpu/drm/i915/intel_pm.c
> @@ -9396,12 +9396,13 @@ static u64 vlv_residency_raw(struct drm_i915_private *dev_priv,
>   			     const i915_reg_t reg)
>   {
>   	u32 lower, upper, tmp;
> +	unsigned long flags;
>   	int loop = 2;
>   
>   	/* The register accessed do not need forcewake. We borrow
>   	 * uncore lock to prevent concurrent access to range reg.
>   	 */
> -	spin_lock_irq(&dev_priv->uncore.lock);
> +	spin_lock_irqsave(&dev_priv->uncore.lock, flags);
>   
>   	/* vlv and chv residency counters are 40 bits in width.
>   	 * With a control bit, we can choose between upper or lower
> @@ -9432,7 +9433,7 @@ static u64 vlv_residency_raw(struct drm_i915_private *dev_priv,
>   	 * now.
>   	 */
>   
> -	spin_unlock_irq(&dev_priv->uncore.lock);
> +	spin_unlock_irqrestore(&dev_priv->uncore.lock, flags);
>   
>   	return lower | (u64)upper << 8;
>   }
> @@ -9451,7 +9452,6 @@ u64 intel_rc6_residency_ns(struct drm_i915_private *dev_priv,
>   		mul = 1000000;
>   		div = dev_priv->czclk_freq;
>   		time_hw = vlv_residency_raw(dev_priv, reg);
> -
>   	} else {
>   		/* 833.33ns units on Gen9LP, 1.28us elsewhere. */
>   		if (IS_GEN9_LP(dev_priv)) {
> 

Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>

Regards,

Tvrtko