linux-kernel - Re: [PATCH] coresight: replicator: Reset replicator if context is lost

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Message-ID: <CANLsYkx640pjt_crfHMUQt25w-xOfoVteYVpocYgPHRw-y-WeQ@mail.gmail.com>
Date:   Mon, 11 May 2020 10:19:22 -0600
From:   Mathieu Poirier <mathieu.poirier@...aro.org>
To:     Sai Prakash Ranjan <saiprakash.ranjan@...eaurora.org>
Cc:     Suzuki K Poulose <suzuki.poulose@....com>,
        Mike Leach <mike.leach@...aro.org>,
        linux-arm-msm <linux-arm-msm@...r.kernel.org>,
        Coresight ML <coresight@...ts.linaro.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Stephen Boyd <swboyd@...omium.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH] coresight: replicator: Reset replicator if context is lost

Hi Sai,

On Mon, 11 May 2020 at 02:34, Sai Prakash Ranjan
<saiprakash.ranjan@...eaurora.org> wrote:
>
> On some QCOM SoCs, replicators in Always-On domain loses its
> context as soon as the clock is disabled. Currently as a part
> of pm_runtime workqueue, clock is disabled after the replicator
> is initialized by amba_pm_runtime_suspend assuming that context
> is not lost which is not true for replicators with such
> limitations. Hence check the replicator idfilter registers
> in dynamic_replicator_enable() and reset again.
>
> Signed-off-by: Sai Prakash Ranjan <saiprakash.ranjan@...eaurora.org>
> ---
>
> More info here - https://lore.kernel.org/patchwork/patch/1231182/
>
> ---
>  drivers/hwtracing/coresight/coresight-replicator.c | 11 +++++++++++
>  1 file changed, 11 insertions(+)
>
> diff --git a/drivers/hwtracing/coresight/coresight-replicator.c b/drivers/hwtracing/coresight/coresight-replicator.c
> index e7dc1c31d20d..11df63f51071 100644
> --- a/drivers/hwtracing/coresight/coresight-replicator.c
> +++ b/drivers/hwtracing/coresight/coresight-replicator.c
> @@ -68,6 +68,17 @@ static int dynamic_replicator_enable(struct replicator_drvdata *drvdata,
>         int rc = 0;
>         u32 reg;
>
> +       /*
> +        * On some QCOM SoCs with replicators in Always-On domain, disabling
> +        * clock will result in replicator losing its context. Currently
> +        * as a part of pm_runtime workqueue, amba_pm_runtime_suspend disables
> +        * clock assuming the context is not lost which is not true for cases
> +        * with hardware limitations as the above.
> +        */
> +       if ((readl_relaxed(drvdata->base + REPLICATOR_IDFILTER0) == 0) &&
> +           (readl_relaxed(drvdata->base + REPLICATOR_IDFILTER1) == 0))
> +               dynamic_replicator_reset(drvdata);
> +

Based on your comment here[1] and the ongoing conversation, I will
wait for a V2.

Thanks,
Mathieu

[1]. https://lkml.org/lkml/2020/5/11/650

>         switch (outport) {
>         case 0:
>                 reg = REPLICATOR_IDFILTER0;
> --
> QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member
> of Code Aurora Forum, hosted by The Linux Foundation
>
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@...ts.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

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