Re: [PATCH] dmaengine: cppi41: Fix oops in cppi41_runtime_resume

[Tony Lindgren <tony-4v6yS6AI5VpBDgjK7y7TUQ@public.gmane.org>]

* Grygorii Strashko <grygorii.strashko-l0cyMroinI0@public.gmane.org> [170113 09:37]:
> On 01/13/2017 10:17 AM, Tony Lindgren wrote:
> > But anyways here's your basic idea plugged into my recent patch and
> > it seems to work. I maybe have missed something though while reading
> > so please check.
> > 
> > The pm_runtime_get/mark_last_busy/put_autosuspend and WARN_ON() we
> > want to keep in cppi41_irq() at least for now :)
> 
> As per my understanding and testing it looks like might be enough to
> have just pm_runtime_mark_last_busy(cdd->ddev.dev); in cppi41_irq().
> But it can be left as is and yes - over all idea is that irq should
> not be triggered if device is Idle.

OK yeah kicking the autoidle timeout is needed here.

> > And I'm thinking we must also callcppi41_run_queue() with spinlock
> > held to prevent out of order triggering of the DMA transfers.
> > 
> > Does this look OK to you?
> 
> I think yes. My current version is mostly similar to yours.

OK will update description and repost shortly.

> > @@ -1150,6 +1165,11 @@ static int __maybe_unused cppi41_resume(struct device *dev)
> >  static int __maybe_unused cppi41_runtime_suspend(struct device *dev)
> >  {
> >  	struct cppi41_dd *cdd = dev_get_drvdata(dev);
> > +	unsigned long flags;
> > +
> > +	spin_lock_irqsave(&cdd->lock, flags);
> > +	cdd->is_suspended = true;
> > +	spin_unlock_irqrestore(&cdd->lock, flags);
> >  
> >  	WARN_ON(!list_empty(&cdd->pending));
> 
> Shouldn't we check list_empty() under spin lock?

Yeah let's do that.

Regards,

Tony
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