linux-kernel - Re: [PATCH v8 2/4] block: add runtime pm helpers

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Date:	Thu, 31 Jan 2013 13:35:35 +0800
From:	Aaron Lu <aaron.lu@...el.com>
To:	Alan Stern <stern@...land.harvard.edu>
Cc:	Jens Axboe <axboe@...nel.dk>, "Rafael J. Wysocki" <rjw@...k.pl>,
	James Bottomley <James.Bottomley@...senpartnership.com>,
	linux-pm@...r.kernel.org, linux-scsi@...r.kernel.org,
	linux-kernel@...r.kernel.org, Aaron Lu <aaron.lwe@...il.com>,
	Shane Huang <shane.huang@....com>
Subject: Re: [PATCH v8 2/4] block: add runtime pm helpers

On Wed, Jan 30, 2013 at 10:54:53AM -0500, Alan Stern wrote:
> On Wed, 30 Jan 2013, Aaron Lu wrote:
> 
> > From: Lin Ming <ming.m.lin@...el.com>
> > 
> > Add runtime pm helper functions:
> > 
> > void blk_pm_runtime_init(struct request_queue *q, struct device *dev)
> >   - Initialization function for drivers to call.
> > 
> > int blk_pre_runtime_suspend(struct request_queue *q)
> >   - If any requests are in the queue, mark last busy and return -EBUSY.
> >     Otherwise set q->rpm_status to RPM_SUSPENDING and return 0.
> > 
> > void blk_post_runtime_suspend(struct request_queue *q, int err)
> >   - If the suspend succeeded then set q->rpm_status to RPM_SUSPENDED.
> >     Otherwise set it to RPM_ACTIVE.
> > 
> > void blk_pre_runtime_resume(struct request_queue *q)
> >   - Set q->rpm_status to RPM_RESUMING.
> > 
> > void blk_post_runtime_resume(struct request_queue *q, int err)
> >   - If the resume succeeded then set q->rpm_status to RPM_ACTIVE
> >     and call __blk_run_queue, then mark last busy and autosuspend.
> >     Otherwise set q->rpm_status to RPM_SUSPENDED.
> > 
> > Signed-off-by: Lin Ming <ming.m.lin@...el.com>
> > Signed-off-by: Aaron Lu <aaron.lu@...el.com>
> 
> > +void blk_pm_runtime_init(struct request_queue *q, struct device *dev)
> > +{
> > +	q->dev = dev;
> > +	q->rpm_status = RPM_ACTIVE;
> > +	pm_runtime_set_autosuspend_delay(q->dev, -1);
> > +	pm_runtime_use_autosuspend(q->dev);
> > +	pm_runtime_mark_last_busy(q->dev);
> > +	pm_runtime_autosuspend(q->dev);
> 
> This last line is no longer needed.  It can't do anything useful, since 
> autosuspends are disabled (the delay is -1).

Right, thanks.
And the mark_last_busy can probably be removed too, it didn't make much
sense here and we can add "driver should call pm_runtime_mark_last_busy
and pm_runtime_autosuspend in its runtime idle callback" to the kernel
doc. What do you think?

Thanks,
Aaron

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