Re: [PATCH 1/1] iommu/arm-smmu-v3: replace writel with writel_relaxed in queue_inc_prod

2017-06-26 Thread Leizhen (ThunderTown)
On 2017/6/26 21:29, Leizhen (ThunderTown) wrote: > > > On 2017/6/21 17:08, Will Deacon wrote: >> On Wed, Jun 21, 2017 at 09:28:23AM +0800, Leizhen (ThunderTown) wrote: >>> On 2017/6/20 19:35, Robin Murphy wrote: On 20/06/17 12:04, Zhen Lei wrote: > This function is protected by

Re: [PATCH 1/1] iommu/arm-smmu-v3: replace writel with writel_relaxed in queue_inc_prod

2017-06-26 Thread Leizhen (ThunderTown)
On 2017/6/21 17:08, Will Deacon wrote: > On Wed, Jun 21, 2017 at 09:28:23AM +0800, Leizhen (ThunderTown) wrote: >> On 2017/6/20 19:35, Robin Murphy wrote: >>> On 20/06/17 12:04, Zhen Lei wrote: This function is protected by spinlock, and the latter will do memory barrier implicitly. So

Re: [PATCH 1/1] iommu/arm-smmu-v3: replace writel with writel_relaxed in queue_inc_prod

2017-06-21 Thread Will Deacon
On Wed, Jun 21, 2017 at 09:28:23AM +0800, Leizhen (ThunderTown) wrote: > On 2017/6/20 19:35, Robin Murphy wrote: > > On 20/06/17 12:04, Zhen Lei wrote: > >> This function is protected by spinlock, and the latter will do memory > >> barrier implicitly. So that we can safely use writel_relaxed. In

Re: [PATCH 1/1] iommu/arm-smmu-v3: replace writel with writel_relaxed in queue_inc_prod

2017-06-20 Thread Leizhen (ThunderTown)
On 2017/6/20 19:35, Robin Murphy wrote: > On 20/06/17 12:04, Zhen Lei wrote: >> This function is protected by spinlock, and the latter will do memory >> barrier implicitly. So that we can safely use writel_relaxed. In fact, the >> dmb operation will lengthen the time protected by lock, which

Re: [PATCH 1/1] iommu/arm-smmu-v3: replace writel with writel_relaxed in queue_inc_prod

2017-06-20 Thread Robin Murphy
On 20/06/17 12:04, Zhen Lei wrote: > This function is protected by spinlock, and the latter will do memory > barrier implicitly. So that we can safely use writel_relaxed. In fact, the > dmb operation will lengthen the time protected by lock, which indirectly > increase the locking confliction in

[PATCH 1/1] iommu/arm-smmu-v3: replace writel with writel_relaxed in queue_inc_prod

2017-06-20 Thread Zhen Lei
This function is protected by spinlock, and the latter will do memory barrier implicitly. So that we can safely use writel_relaxed. In fact, the dmb operation will lengthen the time protected by lock, which indirectly increase the locking confliction in the stress scene. Signed-off-by: Zhen Lei