Messages in this thread | | | Date | Wed, 03 Jun 2020 19:21:04 +0530 | From | Sai Prakash Ranjan <> | Subject | Re: [PATCH 2/2] coresight: tmc: Add shutdown callback for TMC ETR/ETF |
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Hi Robin,
On 2020-06-03 19:10, Robin Murphy wrote: > On 2020-06-03 13:26, Sai Prakash Ranjan wrote: >> Hi Robin, >> >> On 2020-06-03 17:51, Robin Murphy wrote: >>> On 2020-06-03 13:00, Sai Prakash Ranjan wrote: >>>> Hi Robin, Mathieu >>>> >>>> On 2020-06-03 17:07, Robin Murphy wrote: >>>>> On 2020-06-01 22:28, Mathieu Poirier wrote: >>>>>> That being said I'm sure that dependencies on an IOMMU isn't a >>>>>> problem confined >>>>>> to coresight. I am adding Robin Murphy, who added this commit [1], >>>>>> to the thread >>>>>> in the hope that he can provide guidance on the right way to do >>>>>> this. >>>>> >>>>> Right, it's not specific to CoreSight, and it's not even specific >>>>> to >>>>> IOMMUs really. In short, blame kexec ;) >>>>> >>>> >>>> Yes it is not specific to coresight, we are targeting this for all >>>> consumers/clients of SMMU(atleast on SC7180 SoC). We have display >>>> throwing >>>> NoC/interconnect errors[1] during reboot after SMMU is disabled. >>>> This is also not specific to kexec either as you explained here [2] >>>> about >>>> a case with display which is exacly what is happening in our system >>>> [1]. >>> >>> Sure, but those instances are begging the question of why the SMMU is >>> disabled at reboot in the first place ;) >>> >> >> That is what happens in SMMU shutdown callback right? It is the >> reboot/shutdown flow. > > Yes, that's where it happens, but my point is *why* it happens at all. > > hint: `git log --grep=shutdown drivers/iommu/` >
Ah my change :)
> If we could assume the system is always about to be powered off or > reset, we wouldn't need to do anything to the SMMU either ;) >
Are you hinting at removing SMMU shutdown callback altogether ;)
Thanks, Sai
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