linux-kernel - Re: [Patch V3] memory: tegra: Remove clients SID override programming

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Date:   Fri, 25 Nov 2022 16:57:56 +0100
From:   Thierry Reding <thierry.reding@...il.com>
To:     Ashish Mhetre <amhetre@...dia.com>
Cc:     krzysztof.kozlowski@...aro.org, jonathanh@...dia.com,
        dmitry.osipenko@...labora.com, linux-kernel@...r.kernel.org,
        linux-tegra@...r.kernel.org
Subject: Re: [Patch V3] memory: tegra: Remove clients SID override programming

On Fri, Nov 25, 2022 at 09:37:52AM +0530, Ashish Mhetre wrote:
> On newer Tegra releases, early boot SID override programming and SID
> override programming during resume is handled by bootloader.
> In the function tegra186_mc_program_sid() which is getting removed, SID
> override register of all clients is written without checking if secure
> firmware has allowed write on it or not. If write is disabled by secure
> firmware then it can lead to errors coming from secure firmware and hang
> in kernel boot.
> Also, SID override is programmed on-demand during probe_finalize() call
> of IOMMU which is done in tegra186_mc_client_sid_override() in this same
> file. This function does it correctly by checking if write is permitted
> on SID override register. It also checks if SID override register is
> already written with correct value and skips re-writing it in that case.
> 
> Fixes: 393d66fd2cac ("memory: tegra: Implement SID override programming")
> Signed-off-by: Ashish Mhetre <amhetre@...dia.com>
> ---
> Changes in v3:
> - Updated the commit message to point out the bug fix.
> 
> Changes in v2:
> - After offline discussions with Thierry and Jonathan, removed SID
>   override programming during resume as well.
> 
> 
>  drivers/memory/tegra/tegra186.c | 36 ---------------------------------
>  1 file changed, 36 deletions(-)

Acked-by: Thierry Reding <treding@...dia.com>

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