[PATCH v3 0/2] scsi: libsas: Support spinup notification for SAS devices

When a SAS device is in the Active_Wait or Idle_Wait power state, it
returns NOT_READY with ASC/ASCQ = 0x04/0x11 (notify (enable spinup)
required), indicating that a NOTIFY(ENABLE SPINUP) primitive is needed to
trigger media spinup.

Without handling this condition, the SCSI mid-layer will indefinitely retry
the command with ACTION_DELAYED_RETRY, resulting in the disk never spinning
up and becoming unusable. A typical manifestation is:

  sd 4:0:9:0: [sde] Spinning up disk...
  ...not responding...
  sd 4:0:9:0: [sde] Sense Key : Not Ready
  sd 4:0:9:0: [sde] Add. Sense: Logical unit not ready, notify (enable spinup) required

To resolve this, the SAS controller needs to send a NOTIFY(ENABLE SPINUP)
primitive to the target phy, which transitions the device out of the
waiting state and allows normal spinup to proceed.

This patch series addresses the issue entirely within the SAS transport
layer (libsas), reusing the existing phy event framework, without modifying
the generic SCSI mid-layer. This addresses the review feedback from
John Garry on v2.

Changes in v3 (addressing John Garry's review on v2):
- Move spinup notification from scsi_host_template to libsas. Reuse
  the existing phy event framework: add PHYE_NOTIFY_ENABLE_SPINUP
  and lldd_notify_enable_spinup callback.
- Sense detection in sas_ssp_task_response() covers all SAS LLDDs.

Changes in v2 (addressing Sashiko AI review on v1):
- Add softirq context documentation to spinup_notify in
  scsi_host.h
- Defer sl_notify_ssp() to ordered workqueue, fixing
  msleep-in-atomic bug, preventing RMW races on SL_CONTROL, and
  deduplicating concurrent callbacks via queue_work()

Xingui Yang (2):
  scsi: libsas: Add PHYE_NOTIFY_ENABLE_SPINUP phy event for
    ASC/ASCQ=0x04/0x11
  scsi: hisi_sas: Add lldd_notify_enable_spinup callback for SAS devices

 drivers/scsi/hisi_sas/hisi_sas_main.c | 11 +++++++
 drivers/scsi/libsas/sas_internal.h    |  2 ++
 drivers/scsi/libsas/sas_phy.c         | 12 +++++++
 drivers/scsi/libsas/sas_scsi_host.c   | 45 +++++++++++++++++++++++++++
 drivers/scsi/libsas/sas_task.c        |  2 ++
 include/scsi/libsas.h                 |  9 ++++++
 6 files changed, 81 insertions(+)

-- 
2.43.0