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

On 1/04/21 4:40 am, Asutosh Das (asd) wrote:

On 3/31/2021 11:19 AM, Adrian Hunter wrote:

quoted

On 31/03/21 1:31 am, Asutosh Das wrote:

quoted

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 <redacted>
Signed-off-by: Can Guo <redacted>
Signed-off-by: Asutosh Das <redacted>
---

Hi Adrian
Thanks for the comments.

quoted

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?

Dunno, but that seems to be missing:

  commit aa53f580e67b49ec5f4d9bd1de81eb9eb0dc079f
  Author: Can Guo [off-list ref]
  Date:   Tue Feb 23 21:36:47 2021 -0800

    scsi: ufs: Minor adjustments to error handling

which is in v5.12-rc3

quoted

Also came across the issue below:

<SNIP>

quoted

+#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.

quoted

    __ufshcd_wl_suspend(hba, UFS_SHUTDOWN_PM);

quoted

+    return 0;
+}
+#endif

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