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

[Chris Wilson]

Quoting Tvrtko Ursulin (2017-11-23 06:56:49)
> 
> 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>

Ta, pushed this patch. Thanks for the review,
-Chris