linux-kernel - Re: [PATCH 2/2] drivers: qcom: rpmh-rsc: fix read back of trigger register

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Message-ID: <20190722155116.GF25567@codeaurora.org>
Date:   Mon, 22 Jul 2019 09:51:16 -0600
From:   Lina Iyer <ilina@...eaurora.org>
To:     Stephen Boyd <swboyd@...omium.org>
Cc:     andy.gross@...aro.org, bjorn.andersson@...aro.org,
        linux-arm-msm@...r.kernel.org, linux-soc@...r.kernel.org,
        rnayak@...eaurora.org, linux-kernel@...r.kernel.org,
        linux-pm@...r.kernel.org, dianders@...omium.org,
        mkshah@...eaurora.org
Subject: Re: [PATCH 2/2] drivers: qcom: rpmh-rsc: fix read back of trigger
 register

On Fri, Jul 19 2019 at 12:22 -0600, Stephen Boyd wrote:
>Quoting Lina Iyer (2019-07-01 08:29:07)
>> When triggering a TCS to send its contents, reading back the trigger
>> value may return an incorrect value. That is because, writing the
>> trigger may raise an interrupt which could be handled immediately and
>> the trigger value could be reset in the interrupt handler. By doing a
>> read back we may end up spinning waiting for the value we wrote.
>
>Doesn't this need to be squashed into the patch that gets rid of the
>irqs disabled state of this code? It sounds an awful lot like this
>problem only happens now because the previous patch removed the
>irqsave/irqrestore code around this function.
>

True. Could be rolled into that fix.

--Lina