Re: [PATCH] dma: cpp41: Fix handling of error path

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

* Sekhar Nori <nsekhar-l0cyMroinI0@public.gmane.org> [161115 00:35]:
> On Saturday 12 November 2016 12:58 AM, Tony Lindgren wrote:
> > If we return early on pm_runtime_get() error, we need to also call
> > pm_runtime_put_noidle() as pointed out in a musb related thread
> > by Johan Hovold <johan-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>. This is to keep the PM runtime
> > use counts happy.
> > 
> > Fixes: fdea2d09b997 ("dmaengine: cppi41: Add basic PM runtime support")
> > Cc: Johan Hovold <johan-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
> > Signed-off-by: Tony Lindgren <tony-4v6yS6AI5VpBDgjK7y7TUQ@public.gmane.org>
> > ---
> >  drivers/dma/cppi41.c | 11 +++++++++--
> >  1 file changed, 9 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/dma/cppi41.c b/drivers/dma/cppi41.c
> > --- a/drivers/dma/cppi41.c
> > +++ b/drivers/dma/cppi41.c
> > @@ -366,8 +366,11 @@ static int cppi41_dma_alloc_chan_resources(struct dma_chan *chan)
> >  	int error;
> >  
> >  	error = pm_runtime_get_sync(cdd->ddev.dev);
> > -	if (error < 0)
> > +	if (error < 0) {
> > +		pm_runtime_put_noidle(cdd->ddev.dev);
> > +
> 
> If pm_runtime_get_sync() fails due to callback error, then
> rpm_callback() sets dev.power.runtime_error to an error value which gets
> cleared by an explicit call to pm_runtime_set_suspended().
> 
> This will tell the framework that the status of device is suspended.
> Else, the failure will be sticky and on subsequent attempts,
> rpm_resume() will keep returning early instead of trying to resume the
> device again.
> 
> This is as far as I can gather from code. So, I believe the recovery
> path should be:
> 
> 	if (error < 0) {
> 		pm_runtime_set_suspended(cdd->ddev.dev);
> 		pm_runtime_put_noidle(cdd->ddev.dev);
> 
> 		...

Well we should test this :)

BTW, what other users of cppi41 do we have in addition to musb? I think
davinci is or will be using it too?

Regards,

Tony
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