Quoting Sagar Arun Kamble (2018-03-16 04:58:22) > > > On 3/14/2018 3:07 PM, Chris Wilson wrote: > > Currently Ironlake operates under the assumption that rpm awake (and its > > error checking is disabled). As such, we have missed a few places where we > > access registers without taking the rpm wakeref and thus trigger > > warnings. intel_ips being one culprit. > > > > As this involved adding a potentially sleeping rpm_get, we have to > > rearrange the spinlocks slightly and so switch to acquiring a device-ref > > under the spinlock rather than hold the spinlock for the whole > > operation. To be consistent, we make the change in pattern common to the > > intel_ips interface even though this adds a few more atomic operations > > than necessary in a few cases. > > > > Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> > > --- > > drivers/gpu/drm/i915/i915_drv.c | 3 + > > drivers/gpu/drm/i915/intel_pm.c | 138 ++++++++++++++++++++-------------------- > > 2 files changed, 73 insertions(+), 68 deletions(-) > > > > diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c > > index 3d0b7353fb09..5c28990aab7f 100644 > > --- a/drivers/gpu/drm/i915/i915_drv.c > > +++ b/drivers/gpu/drm/i915/i915_drv.c > > @@ -1440,6 +1440,9 @@ void i915_driver_unload(struct drm_device *dev) > > > > i915_driver_unregister(dev_priv); > > > > + /* Flush any external code that still may be under the RCU lock */ > > + synchronize_rcu(); > > + > Hi Chris, > > Will this rcu change be equivalent to > > rcu_assign_pointer(i915_mch_dev, dev_priv) in gpu_ips_init > rcu_assign_pointer(i915_mch_dev, NULL) in gpu_ips_teardown > > eliminating smp_store_mb from init/teardown and synchronize_rcu here. We still have to go through the RCU period on teardown to be sure we flush all readers, but yes, the store_mb can be reduce to RCU_INIT_POINTER() and the mb are overkill as all we really need is the ordering on init, and the explicit rcu sync on teardown. -Chris _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
