Re: [PATCH v14 1/2] scsi: ufs: Enable power management for wlun

From: Adrian Hunter
Date: Wed Mar 31 2021 - 14:20:07 EST


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@xxxxxxxxxxxxxx>
> Signed-off-by: Can Guo <cang@xxxxxxxxxxxxxx>
> Signed-off-by: Asutosh Das <asutoshd@xxxxxxxxxxxxxx>
> ---

Looks good but still doesn't seem to based on the latest tree.

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 is:

__ufshcd_wl_suspend(hba, UFS_SHUTDOWN_PM);

> + return 0;
> +}
> +#endif