Re: [PATCH RFC V2 3/3] scsi_mq: enable runtime PM

Ming Lei
2018-07-17T15:38:53Z

On Tue, Jul 17, 2018 at 03:34:35PM +0000, Bart Van Assche wrote:
> On Tue, 2018-07-17 at 23:30 +0800, Ming Lei wrote:
> > On Tue, Jul 17, 2018 at 03:24:11PM +0200, Christoph Hellwig wrote:
> > > On Fri, Jul 13, 2018 at 04:06:02PM +0800, Ming Lei wrote:
> > > > Usually SCSI supports runtime PM, so pass BLK_MQ_F_SUPPORT_RPM to blk-mq
> > > > core for enabling block runtime PM.
> > >
> > > I still think enabling this unconditionally for any SCSI device was
> > > a mistake, and it is even more so for blk-mq.
> > >
> > > Please only opt in for ufs, ATA first, adding others if wanted by
> > > maintainers.
> >
> > No, this way will cause regression because runtime PM works for
> > all sd/sr device actually, and it isn't related with scsi host.
>
> For which SCSI devices other than ufs and ATA do we need PM support?

As I said, it is any sd/sr device, which can be put down by runtime PM
via START_STOP command if it isn't used for a while.

Thanks,
Ming