Messages in this thread | | | Date | Mon, 14 Nov 2022 14:09:04 +0000 | From | Will Deacon <> | Subject | Re: [GIT PULL] arm64 updates for 6.1-rc1 |
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On Sat, Nov 12, 2022 at 12:48:20AM +0530, Manivannan Sadhasivam wrote: > On Fri, Nov 11, 2022 at 11:10:01PM +0530, Manivannan Sadhasivam wrote: > > On Fri, Nov 11, 2022 at 11:15:11AM +0000, Catalin Marinas wrote: > > > On Tue, Nov 08, 2022 at 10:58:16PM +0530, Amit Pundir wrote: > > > > On Tue, 25 Oct 2022 at 18:08, Amit Pundir <amit.pundir@linaro.org> wrote: > > > > > On Wed, 12 Oct 2022 at 17:24, Catalin Marinas <catalin.marinas@arm.com> wrote: > > > > > > On Sat, Oct 08, 2022 at 08:28:26PM +0530, Amit Pundir wrote: > > > > > > > On Wed, 5 Oct 2022 at 20:11, Catalin Marinas <catalin.marinas@arm.com> wrote: > > > > > > > > Will Deacon (2): > > > > > > > > arm64: dma: Drop cache invalidation from arch_dma_prep_coherent() > > > > > > > > > > > > > > This patch broke AOSP on Dragonboard 845c (SDM845). I don't see any > > > > > > > relevant crash in the attached log and device silently reboots into > > > > > > > USB crash dump mode. The crash is fairly reproducible on db845c. I > > > > > > > could trigger it twice in 5 reboots and it always crash at the same > > > > > > > point during the boot process. Reverting this patch fixes the crash. > > > > > > > > > > > > > > I'm happy to test run any debug patche(s), that would help narrow > > > > > > > down this breakage. > > > [...] > > > > > Further narrowed down the breakage to the userspace daemon rmtfs > > > > > https://github.com/andersson/rmtfs. Is there anything specific in the > > > > > userspace code that I should be paying attention to? > > > > > > Since you don't see anything in the logs like a crash and the system > > > restarts, I suspect it's some deadlock and that's triggering the > > > watchdog. We have an erratum (826319) but that's for Cortex-A53. IIUC > > > SDM845 has Kryo 3xx series which based on some random google searches is > > > derived from A75/A55. Unfortunately the MIDR_EL1 register doesn't match > > > the Arm Ltd numbering, so I have no idea what CPUs these are by looking > > > at the boot log. > > > > > > I wouldn't be surprised if you hit a similar bug, though I couldn't find > > > anything close in the A55 errata notice. > > > > > > While we could revert commit c44094eee32f ("arm64: dma: Drop cache > > > invalidation from arch_dma_prep_coherent()"), if you hit a real hardware > > > issue it may trigger in other scenario where we only do cache cleaning > > > (without invalidate), like arch_sync_dma_for_device(). So I'd rather get > > > to the bottom of this and potentially enable the workaround for this > > > chipset. > > > > > > You could give it a quick try to by adding the MIDR ranges for SDM845 to > > > struct midr_range workaround_clean_cache[]. > > > > > > > I gave it a shot and indeed it fixes the crash on DB845. > > > > > After that I suggest you raise it with Qualcomm to investigate. Normally > > > we ask for an erratum number to enable a workaround and it's only > > > Qualcomm that can provide one here. > > > > > > > I will check with Qualcomm folks and update. > > > > I digged a little further and found that the crash was due to the secure > processor (XPU) violation. It happens because, CPU tried acccessing the memory > after sharing it with the modem for firmware metadata validation.
Can you share more details about this violation, please? For example, is it s read or a write, what size is it, how is it detected?
> Sibi tried fixing this problem earlier by using a hack in the remoteproc driver > [1], but I guess that got negated due to c44094eee32f?
Performing a clean rather than a clean+invalidate when the buffer is allocated (which is what is achieved by c44094eee32f) shouldn't affect this afaict.
> This is a common issue for other Qcom remoteproc drivers as well where CPU > shares a chunk of memory with the modem. There is one more hack in place where > the a chunk of memory is reserved and the driver will do memremap/copy the > data/memunmap using it and share it with modem. > > But is there a better solution overall that you could advise?
I think we need a better understanding of what Qualcomm's SCM firmware is expecting about the state of the buffer pages being shared with the modem before we can suggest other solutions.
Will
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