RE: [PATCH v3 1/1] scsi: ufs: Enable block layer runtime PM for well-known logical units

* RE: [PATCH v3 1/1] scsi: ufs: Enable block layer runtime PM for well-known logical units
       [not found] <1585136153-24852-1-git-send-email-cang@codeaurora.org>
@ 2020-03-25 23:18 ` Avri Altman
  0 siblings, 0 replies; only message in thread
From: Avri Altman @ 2020-03-25 23:18 UTC (permalink / raw)
  To: Can Guo, asutoshd, nguyenb, hongwus, rnayak, linux-scsi,
	kernel-team, saravanak, salyzyn
  Cc: Alim Akhtar, James E.J. Bottomley, Martin K. Petersen,
	Stanley Chu, Bean Huo, Bart Van Assche, Venkat Gopalakrishnan,
	Tomas Winkler, open list

 
> 
> Block layer RPM is enabled for the genernal UFS SCSI devices when they are
> probed by their driver. However block layer RPM is not enabled for UFS
> well-known SCSI devices.
> 
> As UFS SCSI devices have their corresponding BSG char devices, accessing
> a BSG char device via IOCTL may send requests to its corresponding SCSI
> device through its request queue. If BSG IOCTL sends a request to a
> well-known SCSI device when hba is not runtime active, due to block layer
> RPM is not eanbled for the well-known SCSI devices, hba, which is at the
> top of a scsi device's parent chain, shall not be resumed, then unexpected
> error would happen.
> 
> This change enables block layer RPM for the well-known SCSI devices, so
> that block layer can handle RPM for the well-known SCSI devices just like
> for the general SCSI devices.
> 
> Signed-off-by: Can Guo <cang@codeaurora.org>
Reviewed-by: Avri Altman <avri.altman@wdc.com>

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