linux-kernel - Re: [PATCH v2 3/3] iommu/arm-smmu: re-enable context caching in smmu reset operation

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Date:   Wed, 15 Nov 2023 17:43:42 +0100
From:   Konrad Dybcio <konrad.dybcio@...aro.org>
To:     Bibek Kumar Patro <quic_bibekkum@...cinc.com>, will@...nel.org,
        robin.murphy@....com, joro@...tes.org, dmitry.baryshkov@...aro.org,
        a39.skl@...il.com, quic_pkondeti@...cinc.com,
        quic_molvera@...cinc.com
Cc:     linux-arm-msm@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, iommu@...ts.linux.dev,
        linux-kernel@...r.kernel.org, qipl.kernel.upstream@...cinc.com
Subject: Re: [PATCH v2 3/3] iommu/arm-smmu: re-enable context caching in smmu
 reset operation



On 11/14/23 14:56, Bibek Kumar Patro wrote:
> Context caching is re-enabled in the prefetch buffer for Qualcomm SoCs
> through SoC specific reset ops, which is disabled in the default MMU-500
> reset ops, but is expected for context banks using ACTLR register to
> retain the prefetch value during reset and runtime suspend.
> 
> Signed-off-by: Bibek Kumar Patro <quic_bibekkum@...cinc.com>
> ---
And I assume that goes for all SMMU500 implementations?

Looking at the 8550 ACTRL array from patch 2, CPRE is not enabled
at all times.. Is that because of performance, or some other
technical reason?

Will this regress platforms without ACTRL tables?

Konrad