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Message-ID: <2a1047a7-3121-6cbe-d4c5-46bbff0c5cc5@quicinc.com>
Date: Tue, 29 Nov 2022 22:26:13 +0530
From: Nitin Rawat <quic_nitirawa@...cinc.com>
To: Tushar Nimkar <quic_tnimkar@...cinc.com>,
Adrian Hunter <adrian.hunter@...el.com>,
<linux-pm@...r.kernel.org>, <linux-scsi@...r.kernel.org>,
"Rafael J. Wysocki" <rafael@...nel.org>
CC: <linux-arm-msm@...r.kernel.org>,
LKML <linux-kernel@...r.kernel.org>,
<bjorn.andersson@...nel.org>, <quic_mkshah@...cinc.com>,
<quic_lsrao@...cinc.com>, <bvanassche@....org>,
Peter Wang <peter.wang@...iatek.com>
Subject: Re: PM-runtime: supplier looses track of consumer during probe
Hi Adrian,
On 11/21/2022 11:38 AM, Tushar Nimkar wrote:
> Hi Adrian,
>
> On 11/18/2022 8:25 PM, Adrian Hunter wrote:
>> On 4/11/22 11:19, Tushar Nimkar wrote:
>>> Hi linux-pm/linux-scsi,
>
>>>> Process -1
>>>> ufshcd_async_scan context (process 1)
>>>> scsi_autopm_put_device() //0:0:0:0
>>
>> I am having trouble following your description. What function is calling
>> scsi_autopm_put_device() here?
>>
> Below is flow which calls scsi_autopm_put_device()
> Process -1
> ufshcd_async_scan()
> scsi_probe_and_add_lun()
> scsi_add_lun()
> slave_configure()
> scsi_sysfs_add_sdev()
> scsi_autopm_get_device()
> device_add() <- invoked [Process 2] sd_probe()
> scsi_autopm_put_device()
>
>>>> pm_runtime_put_sync()
>>>> __pm_runtime_idle()
>>>> rpm_idle() -- RPM_GET_PUT(4)
>>>> __rpm_callback
>>>> scsi_runtime_idle()
>>>> pm_runtime_mark_last_busy()
>>>> pm_runtime_autosuspend() --[A]
>>>> rpm_suspend() -- RPM_AUTO(8)
>>>> pm_runtime_autosuspend_expiration()
>>>> use_autosuspend is false return 0 --- [B]
>>>> __update_runtime_status to RPM_SUSPENDING
>>>> __rpm_callback()
>>>> __rpm_put_suppliers(dev, false)
>>>> __update_runtime_status to RPM_SUSPENDED
>>>> rpm_suspend_suppliers()
>>>> rpm_idle() for supplier -- RPM_ASYNC(1) return
>>>> (-EAGAIN) [ Other consumer active for supplier]
>>>> rpm_suspend() – END with return=0
>>>> scsi_runtime_idle() END return (-EBUSY) always.
>>
>> Not following here either. Which device is EBUSY and why?
>
> scsi_runtime_idle() return -EBUSY always [3]
> Storage/scsi team can better explain -EBUSY implementation.
EBUSY is returned from below code for consumer dev 0:0:0:0.
scsi_runtime_idle is called from scsi_autopm_put_device which inturn is
called from ufshcd_async_scan (Process 1 as per above call stack)
static int scsi_runtime_idle(struct device *dev)
{
:
if (scsi_is_sdev_device(dev)) {
pm_runtime_mark_last_busy(dev);
pm_runtime_autosuspend(dev);
return -EBUSY; ---> EBUSY returned from here.
}
}
>
> [3]
> https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/tree/drivers/scsi/scsi_pm.c?h=next-20221118#n210
>
>
>>>>
>>>> [1]: https://lore.kernel.org/lkml/4748074.GXAFRqVoOG@kreacher/T/
>>>> [2]: https://lkml.org/lkml/2022/10/12/259
>>>>
>>>> Thanks,
>>>> Tushar Nimkar
>>
> Thanks,
> Tushar Nimkar
Thanks,
Nitin
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