[PATCH] iomm/arm-smmu: Add stall implementation hook

Robin Murphy robin.murphy at arm.com
Thu May 7 14:56:28 UTC 2020


On 2020-05-07 1:06 pm, Sai Prakash Ranjan wrote:
[...]
> We could have our own context fault handler in QCOM implementation,
> but that would just be duplicating things from arm-smmu context fault
> handler. So I did not think it makes much sense to have our own
> fault handler in qcom impl just for enabling stall model.

Hmm, it's probably worth thinking ahead a bit here, to the "actually 
doing things with stalls" plan. I don't have a clear picture off-hand of 
how well the new device fault handler API might fit into arm-smmu - at 
the very least trying to make it truly generic implies having to play 
nasty tricks with disable_irq() for the general case given the "IRQ may 
remain asserted while SS is active" possibility, and that isn't 
particularly inviting. Not to mention tying it into the 
pretend-auxdomain stuff that *is* rather dependent on the qcom impl. If 
it turns out that you'll eventually have to reimplement the IRQ handler 
anyway for all that, then starting off down that route *might* work out 
cleaner and less hassle overall.

Robin.


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