On Tue, Nov 15, 2016 at 12:58:17PM -0800, Tony Lindgren wrote:
> * Sekhar Nori <nsekhar@xxxxxx> [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@xxxxxxxxxx>. This is to keep the PM runtime
> > > use counts happy.
> > >
> > > Fixes: fdea2d09b997 ("dmaengine: cppi41: Add basic PM runtime support")
> > > Cc: Johan Hovold <johan@xxxxxxxxxx>
> > > Signed-off-by: Tony Lindgren <tony@xxxxxxxxxxx>
> > > ---
> > > 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?
AFAIK, musb on am335x, da8xx, am35x uses cppi41. davinci musb uses cppi,
not cppi41.
Regards,
-Bin.
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