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SubjectRe: [PATCH v14 1/2] scsi: ufs: Enable power management for wlun
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On 3/31/2021 11:19 AM, Adrian Hunter wrote:
> On 31/03/21 1:31 am, Asutosh Das wrote:
>> During runtime-suspend of ufs host, the scsi devices are
>> already suspended and so are the queues associated with them.
>> But the ufs host sends SSU (START_STOP_UNIT) to wlun
>> during its runtime-suspend.
>> During the process blk_queue_enter checks if the queue is not in
>> suspended state. If so, it waits for the queue to resume, and never
>> comes out of it.
>> The commit
>> (d55d15a33: scsi: block: Do not accept any requests while suspended)
>> adds the check if the queue is in suspended state in blk_queue_enter().
>>
>> Call trace:
>> __switch_to+0x174/0x2c4
>> __schedule+0x478/0x764
>> schedule+0x9c/0xe0
>> blk_queue_enter+0x158/0x228
>> blk_mq_alloc_request+0x40/0xa4
>> blk_get_request+0x2c/0x70
>> __scsi_execute+0x60/0x1c4
>> ufshcd_set_dev_pwr_mode+0x124/0x1e4
>> ufshcd_suspend+0x208/0x83c
>> ufshcd_runtime_suspend+0x40/0x154
>> ufshcd_pltfrm_runtime_suspend+0x14/0x20
>> pm_generic_runtime_suspend+0x28/0x3c
>> __rpm_callback+0x80/0x2a4
>> rpm_suspend+0x308/0x614
>> rpm_idle+0x158/0x228
>> pm_runtime_work+0x84/0xac
>> process_one_work+0x1f0/0x470
>> worker_thread+0x26c/0x4c8
>> kthread+0x13c/0x320
>> ret_from_fork+0x10/0x18
>>
>> Fix this by registering ufs device wlun as a scsi driver and
>> registering it for block runtime-pm. Also make this as a
>> supplier for all other luns. That way, this device wlun
>> suspends after all the consumers and resumes after
>> hba resumes.
>>
>> Co-developed-by: Can Guo <cang@codeaurora.org>
>> Signed-off-by: Can Guo <cang@codeaurora.org>
>> Signed-off-by: Asutosh Das <asutoshd@codeaurora.org>
>> ---
>
Hi Adrian
Thanks for the comments.
> Looks good but still doesn't seem to based on the latest tree.
>
Umm, it's based on the below:
git://git.kernel.org/pub/scm/linux/kernel/git/mkp/scsi.git
Branch: refs/heads/for-next

The top most change is e27f3c8 on 27th March'21.
Which tree are you referring to that'd be latest?

> Also came across the issue below:
>
> <SNIP>
>
>> +#ifdef CONFIG_PM_SLEEP
>> +static int ufshcd_wl_poweroff(struct device *dev)
>> +{
>> + ufshcd_wl_shutdown(dev);
>
> This turned out to be wrong. This is a PM op and SCSI has already
> quiesced the sdev's. All that is needed isOk. I'll fix it in the next version.

>
> __ufshcd_wl_suspend(hba, UFS_SHUTDOWN_PM);
>
>> + return 0;
>> +}
>> +#endif


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