scsi: hisi_sas: Check usage count only when the runtime PM status is RPM_SUSPENDING

Users can suspend the machine with 'echo disk > /sys/power/state', but
the suspend will fail because the SAS controller cannot be suspended:

[root@localhost ~]# echo freeze > /sys/power/state
-bash: echo: write error: Device or resource busy
[15104.142955] PM: suspend entry (s2idle)
...
[15104.283465] hisi_sas_v3_hw 0000:32:04.0: entering suspend state
[15104.283480] hisi_sas_v3_hw 0000:30:04.0: entering suspend state
[15104.283500] hisi_sas_v3_hw 0000:32:04.0: PM suspend: host status cannot be suspended
[15104.283508] hisi_sas_v3_hw 0000:30:04.0: PM suspend: host status cannot be suspended
[15104.283516] hisi_sas_v3_hw 0000:32:04.0: PM: pci_pm_suspend(): suspend_v3_hw+0x0/0x210 [hisi_sas_v3_hw] returns -16
[15104.283527] hisi_sas_v3_hw 0000:32:04.0: PM: dpm_run_callback(): pci_pm_suspend+0x0/0x1c0 returns -16
[15104.283524] hisi_sas_v3_hw 0000:30:04.0: PM: pci_pm_suspend(): suspend_v3_hw+0x0/0x210 [hisi_sas_v3_hw] returns -16
[15104.283533] hisi_sas_v3_hw 0000:32:04.0: PM: failed to suspend async: error -16
[15104.283536] hisi_sas_v3_hw 0000:30:04.0: PM: dpm_run_callback(): pci_pm_suspend+0x0/0x1c0 returns -16
[15104.283542] hisi_sas_v3_hw 0000:30:04.0: PM: failed to suspend async: error -16

The problem is that when the ->runtime_suspend() callback
suspend_v3_hw() is executing, the current runtime PM status is
RPM_ACTIVE and the usage count of the controller is not 0, so return
immediately.

To fix it, Check the device usage count only when the runtime PM status
is RPM_SUSPENDING.

Signed-off-by: Yihang Li <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Reviewed-by: Xiang Chen <[email protected]>
Signed-off-by: Martin K. Petersen <[email protected]>

Author: Yihang Li

drivers/scsi/hisi_sas/hisi_sas_v3_hw.c

@@ -5048,7 +5048,8 @@ static int _suspend_v3_hw(struct device *device)
 	interrupt_disable_v3_hw(hisi_hba);
 
 #ifdef CONFIG_PM
-	if (atomic_read(&device->power.usage_count)) {
+	if ((device->power.runtime_status == RPM_SUSPENDING) &&
+	    atomic_read(&device->power.usage_count)) {
 		dev_err(dev, "PM suspend: host status cannot be suspended\n");
 		rc = -EBUSY;
 		goto err_out;