ARM: implement workaround for Cortex-A9/PL310/PCIe deadlock
Get series with b4
b4 am 20140407111002.36488aed@skateVersions newest first
- v1 Latest0 of 3 patches 0 repliesNew
Patches in v1 No applies recorded yet
None of the 3 patches the cover letter announces are in this archive.
Reviews trailers per patch
No Reviewed-by, Acked-by or Tested-by trailers for v1 yet.
Cover letter [PATCH 0/3] ARM: implement workaround for Cortex-A9/PL310/PCIe deadlock
Dear Russell King - ARM Linux,
Quoted 7 lines · Russell King - ARM Linux
Quoted 5 lines
Any comments about the proposed patches? These are important for the recent Armada 375/38x platforms and I'm sure will require a bit of discussion. Moreover, one of the patch affects the L2 cache driver that Russell is currently working on, so it would be nice if we could get the discussion going soon.
Will is away for another week and a half.
Ok. However I believe Will and Catalin are the best placed to give all the fine details about this problem.
Quoted 7 lines
There is an important point to be made about the L2 cache though - it is not possible to disable the "sync" at the L2 cache - any register write automatically invokes a sync before it is actioned, so avoiding the explicit sync doesn't stop them from happening, it just reduces the number which occur.
Is it possible that you are hitting one of the PL310 errata?
As far as I'm aware, there is no PL310 errata registered for this
problem: at least I asked Will and Catalin about this, and they never came up with a PL310 errata. My understanding is that the problem here is not a deficiency of the PL310 itself, but rather an unfortunate interaction between the PL310 behavior, the hardware I/O coherency and the PCIe transactions.
The suggested fix to disable explicit outer cache sync, and map PCIe regions are strongly ordered was proposed by ARM as a solution to the deadlocks, and it was tested successfully.
I am hoping that Catalin and Will will enter the discussion and give the details you need to fully understand the problem.
Thanks,
Thomas
Signature · 3 lines
Thomas Petazzoni, CTO, Free Electrons Embedded Linux, Kernel and Android engineering http://free-electrons.com