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From: Vivek Gautam <vivek.gautam@codeaurora.org>
To: Will Deacon <will.deacon@arm.com>, robdclark@gmail.com
Cc: joro@8bytes.org, andy.gross@linaro.org, robin.murphy@arm.com,
	bjorn.andersson@linaro.org, iommu@lists.linux-foundation.org,
	mark.rutland@arm.com, david.brown@linaro.org, tfiga@chromium.org,
	swboyd@chromium.org, linux-kernel@vger.kernel.org,
	linux-arm-msm@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 0/5] Qcom smmu-500 TLB invalidation errata for sdm845
Date: Wed, 5 Sep 2018 14:52:21 +0530	[thread overview]
Message-ID: <3f74124c-b09f-a92d-117d-a747d33a4561@codeaurora.org> (raw)
In-Reply-To: <ad4e9f85-ff57-ad26-fb25-7b4c08683a52@codeaurora.org>


On 8/14/2018 5:54 PM, Vivek Gautam wrote:
> Hi Will,
>
>
> On 8/14/2018 5:10 PM, Will Deacon wrote:
>> Hi Vivek,
>>
>> On Tue, Aug 14, 2018 at 04:25:23PM +0530, Vivek Gautam wrote:
>>> Qcom's implementation of arm,mmu-500 on sdm845 has a 
>>> functional/performance
>>> errata [1] because of which the TCU cache look ups are stalled during
>>> invalidation cycle. This is mitigated by serializing all the 
>>> invalidation
>>> requests coming to the smmu.
>> How does this implementation differ from the one supported by 
>> qcom_iommu.c?
>> I notice you're adding firmware hooks here, which we avoided by 
>> having the
>> extra driver. Please help me understand which devices exist, how they
>> differ, and which drivers are intended to support them!
>
> IIRC, the qcom_iommu driver was intended to support the static context 
> bank - SID
> mapping, and is very specific to the smmu-v2 version present on 
> msm8916 soc.
> However, this is the qcom's mmu-500 implementation specific errata. 
> qcom_iommu
> will not be able to support mmu-500 configurations.
> Rob Clark can add more.
> Let you know what you suggest.

Rob, can you please comment about how qcom-smmu driver has different 
implementation
from arm-smmu driver?
Will, in case we would want to use arm-smmu driver, what would you 
suggest for
having the firmware hooks?
Thanks.

Best regards
Vivek
>
>>
>> Also -- you didn't CC all the maintainers for the firmware bits, so 
>> adding
>> Andy here for that, and Rob for the previous question.
>
> I added Andy to the series, would you want me to add Rob H also?
>
> Best regards
> Vivek
>
>>
>> Thanks,
>>
>> Will
>


  reply	other threads:[~2018-09-05  9:22 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-08-14 10:55 [PATCH 0/5] Qcom smmu-500 TLB invalidation errata for sdm845 Vivek Gautam
2018-08-14 10:55 ` [PATCH 1/5] firmware: qcom_scm-64: Add atomic version of qcom_scm_call Vivek Gautam
2018-08-14 10:55 ` [PATCH 2/5] firmware/qcom_scm: Add atomic version of io read/write APIs Vivek Gautam
2018-08-14 10:55 ` [PATCH 3/5] firmware/qcom_scm: Add scm call to handle smmu errata Vivek Gautam
2018-08-14 10:55 ` [PATCH 4/5] iommu/arm-smmu: Make way to add Qcom's smmu-500 errata handling Vivek Gautam
2018-08-14 11:40   ` Will Deacon
2018-08-14 12:28     ` Vivek Gautam
2018-08-14 16:59   ` Robin Murphy
2018-08-28  6:59     ` Vivek Gautam
2018-08-14 10:55 ` [PATCH 5/5] iommu/arm-smmu: Add support to handle Qcom's TLBI serialization errata Vivek Gautam
2018-08-14 11:40 ` [PATCH 0/5] Qcom smmu-500 TLB invalidation errata for sdm845 Will Deacon
2018-08-14 12:24   ` Vivek Gautam
2018-09-05  9:22     ` Vivek Gautam [this message]
2018-09-05 10:04       ` Rob Clark
2018-09-05 11:25         ` Vivek Gautam

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