linux-kernel - Re: [PATCH] drivers: qcom: rpmh-rsc: Do not read back the register write on trigger

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Message-ID: <CAD=FV=Xk_1=eCvqLPPnYLrQWf1zVy+iEHs=DWEubb6n5ub3Wxw@mail.gmail.com>
Date:   Thu, 3 Dec 2020 13:15:58 -0800
From:   Doug Anderson <dianders@...omium.org>
To:     Maulik Shah <mkshah@...eaurora.org>
Cc:     Bjorn Andersson <bjorn.andersson@...aro.org>,
        Andy Gross <agross@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        linux-arm-msm <linux-arm-msm@...r.kernel.org>,
        Lina Iyer <ilina@...eaurora.org>,
        Srinivas Rao L <lsrao@...eaurora.org>,
        Stephen Boyd <swboyd@...omium.org>
Subject: Re: [PATCH] drivers: qcom: rpmh-rsc: Do not read back the register
 write on trigger

Hi,

On Tue, Nov 24, 2020 at 1:53 AM Maulik Shah <mkshah@...eaurora.org> wrote:
>
> From: Lina Iyer <ilina@...eaurora.org>
>
> 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.
>
> A write_tcs_reg_sync() would read back the value that is written and try
> to match it to the value written to ensure that the value is written,
> but if that value is different, we may see false error for same.
>
> Signed-off-by: Lina Iyer <ilina@...eaurora.org>
> Signed-off-by: Maulik Shah <mkshah@...eaurora.org>
> ---
>  drivers/soc/qcom/rpmh-rsc.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

Fixes: 658628e7ef78 ("drivers: qcom: rpmh-rsc: add RPMH controller for
QCOM SoCs")
Signed-off-by: Douglas Anderson <dianders@...omium.org>