Messages in this thread | | | Date | Mon, 20 Apr 2020 23:40:42 +0530 | From | Sai Prakash Ranjan <> | Subject | Re: [PATCHv3 4/6] iommu/arm-smmu-qcom: Request direct mapping for modem device |
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Hi Robin,
On 2020-04-20 22:39, Robin Murphy wrote: > On 2020-04-20 5:42 pm, Sai Prakash Ranjan wrote: >> From: Sibi Sankar <sibis@codeaurora.org> >> >> Request direct mapping for modem on platforms which don't have >> TrustZone >> (which programs the modem SIDs) to prevent the following global faults >> seen >> on Cheza/Trogdor: > > Not strictly true - it's patch #6/6 that prevents *those* faults (and > these days the driver should be reporting unmatched streams a little > more helpfully). This change would resolve the context faults and/or > weird memory corruption that might result from applying patch #6 alone > - this is the crazy thing where transactions sometimes go directly to > DRAM round the side of the SMMU so we can never safely remap anything, > right? >
True this doesnt prevent global faults, the fault details should go to patch6. I'll update the commit msg something like below:
The Q6 modem sub-system has direct access to DDR through memnoc. Also SMMU is not expected to provide access control/translation for these SIDs (sandboxing of the modem is achieved through XPUs engaged using SMC calls).
Thanks, Sai
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