linux-kernel - Re: [PATCH v3 2/2] soc: qcom: rpmh-rsc: Timeout after 1 second in write_tcs_reg

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Date:   Thu, 28 May 2020 17:14:36 +0530
From:   Maulik Shah <mkshah@...eaurora.org>
To:     Douglas Anderson <dianders@...omium.org>,
        Andy Gross <agross@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>
Cc:     mka@...omium.org, joe@...ches.com, swboyd@...omium.org,
        evgreen@...omium.org, linux-arm-msm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 2/2] soc: qcom: rpmh-rsc: Timeout after 1 second in
 write_tcs_reg_sync()

Hi Doug,

During suspend-resume with this change on sc7180 using latest 
linux-next, below warning was reported.

WARNING: CPU: 0 PID: 5324 at kernel/time/timekeeping.c:754 
ktime_get+0x94/0x9c
  ktime_get+0x94/0x9c
  write_tcs_reg_sync+0x4c/0x130
  tcs_invalidate+0x64/0xa4
  rpmh_rsc_invalidate+0x20/0x38
  rpmh_flush+0x58/0x1ec
  rpmh_rsc_cpu_pm_callback+0xe4/0x144
  notifier_call_chain+0x58/0x90
  __atomic_notifier_call_chain+0x48/
  cpu_pm_notify+0x40/0x6c
  cpu_pm_enter+0x34/0x7c
  cpu_pm_suspend+0x10/0x20
  syscore_suspend+0x128/0x2a4
  suspend_devices_and_enter+0x5e0/0x8a0

This seems to be because timekeeping is already suspend by this time.

Thanks,
Maulik

On 4/15/2020 10:30 PM, Douglas Anderson wrote:
> If our data still isn't there after 1 second, shout and give up.
>
> Reported-by: Joe Perches <joe@...ches.com>
> Signed-off-by: Douglas Anderson <dianders@...omium.org>
> Reviewed-by: Stephen Boyd <swboyd@...omium.org>
> ---
>
> Changes in v3:
> - The register should be hex.
>
> Changes in v2:
> - Patch ("Timeout after 1 second") new for v2.
>
>   drivers/soc/qcom/rpmh-rsc.c | 12 +++++++-----
>   1 file changed, 7 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/soc/qcom/rpmh-rsc.c b/drivers/soc/qcom/rpmh-rsc.c
> index ce39d8399312..e09d1ada0cd2 100644
> --- a/drivers/soc/qcom/rpmh-rsc.c
> +++ b/drivers/soc/qcom/rpmh-rsc.c
> @@ -10,6 +10,7 @@
>   #include <linux/delay.h>
>   #include <linux/interrupt.h>
>   #include <linux/io.h>
> +#include <linux/iopoll.h>
>   #include <linux/kernel.h>
>   #include <linux/list.h>
>   #include <linux/module.h>
> @@ -175,12 +176,13 @@ static void write_tcs_reg(const struct rsc_drv *drv, int reg, int tcs_id,
>   static void write_tcs_reg_sync(const struct rsc_drv *drv, int reg, int tcs_id,
>   			       u32 data)
>   {
> +	u32 new_data;
> +
>   	writel(data, tcs_reg_addr(drv, reg, tcs_id));
> -	for (;;) {
> -		if (data == readl(tcs_reg_addr(drv, reg, tcs_id)))
> -			break;
> -		udelay(1);
> -	}
> +	if (readl_poll_timeout_atomic(tcs_reg_addr(drv, reg, tcs_id), new_data,
> +				      new_data == data, 1, USEC_PER_SEC))
> +		pr_err("%s: error writing %#x to %d:%#x\n", drv->name,
> +		       data, tcs_id, reg);
>   }
>   
>   /**

-- 
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