Re: [PATCH v15 1/2] scsi: ufs: Enable power management for wlun

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On 4/7/2021 3:21 AM, Adrian Hunter wrote:
On 6/04/21 8:52 pm, 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>
---

v15 seems to be missing the updates to ufs_debugfs_get/put_user_access
that were in v14:


@@ -60,14 +60,14 @@ __acquires(&hba->host_sem)
  		up(&hba->host_sem);
  		return -EBUSY;
  	}
-	pm_runtime_get_sync(hba->dev);
+	scsi_autopm_get_device(hba->sdev_ufs_device);
  	return 0;
  }
static void ufs_debugfs_put_user_access(struct ufs_hba *hba)
  __releases(&hba->host_sem)
  {
-	pm_runtime_put_sync(hba->dev);
+	scsi_autopm_put_device(hba->sdev_ufs_device);
  	up(&hba->host_sem);
  }
Also from last comments, 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);


Yikes! Thanks, let me fix this and push the correct series.

-asd

--
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
Linux Foundation Collaborative Project



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