Messages in this thread | | | Date | Fri, 25 Nov 2022 09:19:49 +0530 | Subject | Re: [Patch V2] memory: tegra: Remove clients SID override programming | From | Ashish Mhetre <> |
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On 11/24/2022 5:04 PM, Krzysztof Kozlowski wrote: > External email: Use caution opening links or attachments > > > On 24/11/2022 11:20, Ashish Mhetre wrote: >> On 11/22/2022 4:44 PM, Krzysztof Kozlowski wrote: >>> External email: Use caution opening links or attachments >>> >>> >>> On 22/11/2022 06:31, Ashish Mhetre wrote: >>>> On newer Tegra releases, early boot SID override programming and SID >>>> override programming during resume is handled by bootloader. >>>> 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 more 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. >>>> Hence, removing the SID override programming of all clients. >>>> >>>> Fixes: 393d66fd2cac ("memory: tegra: Implement SID override programming") >>> I could not get from commit msg what is the bug being fixed. You just >>> said "more correctly", but usually things are either correct or not. >>> What are visible effects of the bug? >>> >>> Otherwise it sounds more like optimization or a bit better approach, but >>> not a bugfix. >>> >>> Best regards, >>> Krzysztof >> Thanks for the review. 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. So, that's a possible bug. > Please add it to commit msg, because it justifies Fixes tag and probably > backport.
Sure, I will send V3 with updated commit message. Thank you.
>> Also, it's an optimization over current approach because it saves time by >> removing re-writing of these SID override registers as in new Tegra releases >> SID override of all clients is programmed by bootloader. So, MC driver don't >> need to program them again. > Best regards, > Krzysztof >
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