linux-kernel - Re: [PATCH] soc: qcom: llcc: Fix dis_cap_alloc and retain_on

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Message-ID: <d1e3adb5-b179-a119-fc0c-f92c2b84c7c2@quicinc.com>
Date:   Tue, 7 Nov 2023 18:46:14 +0530
From:   Mukesh Ojha <quic_mojha@...cinc.com>
To:     Stephen Boyd <swboyd@...omium.org>,
        Atul Dhudase <quic_adhudase@...cinc.com>,
        Bjorn Andersson <quic_bjorande@...cinc.com>
CC:     <agross@...nel.org>, <andersson@...nel.org>,
        <konrad.dybcio@...aro.org>, <isaacm@...eaurora.org>,
        <dianders@...omium.org>, <linux-arm-msm@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] soc: qcom: llcc: Fix dis_cap_alloc and retain_on_pc
 configuration



On 11/7/2023 3:25 AM, Stephen Boyd wrote:
> Quoting Mukesh Ojha (2023-11-05 22:54:28)
>>
>>
>> On 11/4/2023 1:03 AM, Bjorn Andersson wrote:
>>> On Fri, Nov 03, 2023 at 04:27:12PM +0530, Atul Dhudase wrote:
>>>> While programming dis_cap_alloc and retain_on_pc, set a bit
>>>> corresponding to a specific SCID without disturbing the
>>>> previously configured bits.
>>>>
>>>
>>> As far as I can see, the only invocation of _qcom_llcc_cfg_program()
>>> comes from qcom_llcc_cfg_program(), which is only called once, from
>>> qcom_llcc_probe(), and here also seems to only be the single write to
>>> these two registers.
>>
>> It does not look to be single write but the write is for each slice
>> in the same register which was overriding other slices values.
> 
> Can you add that detail to the commit text? What's the seriousness of
> the issue? Why should it be backported to stable? Is something seriously
> broken because a slice configuration is overwritten? Does it mean that
> some allocation made in a slice is being lost over power collapse (pc)
> when it shouldn't be?

@Atul will update the commit text as per suggestion.

And yes, without this change, retention feature will not work properly.

-Mukesh