linux-kernel - Re: [PATCH V11 1/2] i2c: i2c-qcom-geni: Add shutdown callback for i2c

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Message-ID: <f6cb21107dd7e7104bb40aabb8d2bf90@codeaurora.org>
Date:   Mon, 31 May 2021 10:54:16 +0530
From:   rojay@...eaurora.org
To:     Roja Rani Yarubandi <rojay@...eaurora.org>
Cc:     swboyd@...omium.org, dianders@...omium.org,
        saiprakash.ranjan@...eaurora.org, gregkh@...uxfoundation.org,
        mka@...omium.org, skananth@...eaurora.org,
        msavaliy@....qualcomm.com, skakit@...eaurora.org,
        rnayak@...eaurora.org, agross@...nel.org,
        bjorn.andersson@...aro.org, linux-arm-msm@...r.kernel.org,
        linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org,
        sumit.semwal@...aro.org, linux-media@...r.kernel.org
Subject: Re: [PATCH V11 1/2] i2c: i2c-qcom-geni: Add shutdown callback for i2c

On 2021-05-28 13:41, Wolfram Sang wrote:
> On Tue, May 25, 2021 at 06:40:50PM +0530, Roja Rani Yarubandi wrote:
>> If the hardware is still accessing memory after SMMU translation
>> is disabled (as part of smmu shutdown callback), then the
>> IOVAs (I/O virtual address) which it was using will go on the bus
>> as the physical addresses which will result in unknown crashes
>> like NoC/interconnect errors.
>> 
>> So, implement shutdown callback for i2c driver to suspend the bus
>> during system "reboot" or "shutdown".
>> 
>> Fixes: 37692de5d523 ("i2c: i2c-qcom-geni: Add bus driver for the 
>> Qualcomm GENI I2C controller")
>> Signed-off-by: Roja Rani Yarubandi <rojay@...eaurora.org>
> 
> Do we need patch 1 after patch 2 was applied? I always thought all
> devices are suspended before shutdown/reboot?
> 

Yes, both patch 1 and patch 2 are required.
Devices are not suspended during shutdown/reboot.

> Nice to see that 'mark_adapter_suspended' becomes useful again!

Thanks,
Roja