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From: Sibi Sankar <>
To: Joerg Roedel <>
Subject: Re: [PATCH 0/3] Request direct mapping for modem firmware subdevice
Date: Tue, 10 Mar 2020 19:30:50 +0530
Message-ID: <> (raw)
In-Reply-To: <>

Hey Joerg,
Thanks for taking time to review
the series!

On 2020-03-10 16:53, Joerg Roedel wrote:
> On Mon, Mar 09, 2020 at 11:52:52PM +0530, Sibi Sankar wrote:
>> The Q6 modem sub-system has direct access to DDR through memnoc and
>> an indirect access routed through a SMMU which MSS CE (crypto engine
>> sub-component of MSS) uses during out of reset sequence. Request 
>> direct
>> mapping for the modem-firmware subdevice since smmu is not expected
>> to provide access control/translation for these SIDs (sandboxing of 
>> the
>> modem is achieved through XPUs engaged using SMC calls).
> So the DMA accesses are initiated by the firmware and need to be direct
> mapped? Which memory region do they access?

The accesses are initiated by the firmware
and they access modem reserved regions.
However as explained in ^^ any accesses
outside the region will result in a violation
and is controlled through XPUs (protection units).

the firmware SIDs will explicitly need to
be directly mapped to avoid observing
global faults in the absence of secure
firmware (TrustZone) programming the modem
SIDs as S2CR-Bypass.

> Regards,
> 	Joerg

Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project.

  reply index

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-09 18:22 Sibi Sankar
2020-03-09 18:22 ` [PATCH 1/3] iommu: Export "iommu_request_dm_for_dev" Sibi Sankar
2020-03-09 18:22 ` [PATCH 2/3] dt-bindings: remoteproc: qcom: Add modem-firmware bindings Sibi Sankar
2020-03-09 18:22 ` [PATCH 3/3] remoteproc: qcom_q6v5_mss: Request direct mapping for firmware subdevice Sibi Sankar
2020-03-10 11:23 ` [PATCH 0/3] Request direct mapping for modem " Joerg Roedel
2020-03-10 14:00   ` Sibi Sankar [this message]
2020-03-10 16:23     ` Joerg Roedel
2020-03-10 16:44       ` Robin Murphy
2020-03-12  6:28         ` Sai Prakash Ranjan
2020-03-12 12:05           ` Robin Murphy
2020-03-23  9:43             ` Sai Prakash Ranjan
2020-03-16 15:50 ` Christoph Hellwig
2020-03-16 16:37   ` Sibi Sankar

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