lkml.org 
[lkml]   [2020]   [Apr]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCHv3 4/6] iommu/arm-smmu-qcom: Request direct mapping for modem device
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

--
QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a
member
of Code Aurora Forum, hosted by The Linux Foundation

\
 
 \ /
  Last update: 2020-04-20 20:11    [W:0.059 / U:0.592 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site