On Mon, Sep 17, 2018 at 08:56:34PM +0200, Andreas Kemnade wrote:
> Hi Dmitry,
>
> On Mon, 17 Sep 2018 10:51:31 -0700
> Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx> wrote:
>
> > Hi Andreas,
> >
> > On Mon, Sep 17, 2018 at 07:22:54AM +0200, Andreas Kemnade wrote:
> > > When runtime is not enabled, pm_runtime_get_sync() returns -EACCESS,
> > > the counter will be incremented but the resume callback not called,
> > > so enumeration and charging will not start properly.
> > > To avoid that happen, wait and try again later.
> > >
> > > Practically this happens when the device is woken up from suspend by
> > > plugging in usb.
> > >
> > > Signed-off-by: Andreas Kemnade <andreas@xxxxxxxxxxxx>
> > > ---
> > > drivers/phy/ti/phy-twl4030-usb.c | 9 +++++++++
> > > 1 file changed, 9 insertions(+)
> > >
> > > diff --git a/drivers/phy/ti/phy-twl4030-usb.c b/drivers/phy/ti/phy-twl4030-usb.c
> > > index a44680d64f9b..1f3cf4e48383 100644
> > > --- a/drivers/phy/ti/phy-twl4030-usb.c
> > > +++ b/drivers/phy/ti/phy-twl4030-usb.c
> > > @@ -552,6 +552,15 @@ static irqreturn_t twl4030_usb_irq(int irq, void *_twl)
> > >
> > > status = twl4030_usb_linkstat(twl);
> > >
> > > + /* we might get here too early when runtime is not ready yet
> > > + * and we will get an EACCESS later, so try again later
> > > + */
> >
> > How exactly can this happen? What disables (and later re-enables)
> > runtime PM?
> If the whole resume process is started by plugging in usb, the
> interrupt will be triggered still in the resume process so that
> runtime resume is not yet possible, pm_runtime_get_sync() returns
> EACCESS
I see. This all seems a bit wonky, to be honest. I would expect that the
driver would have a suspend routine that disables interrupt and also
configure interrupt for wakeup (enable_irq_wake) and kick bus scanning
from there instead of aborting interrupt handler...
>
> > How can we guarantee that the interrupt will be
> > re-triggered?
> >
> The interrupt will not be re-triggered but the handler will be
> called at some other places...
>
> > > + if (!pm_runtime_enabled(twl->dev)) {
> > > + cancel_delayed_work(&twl->id_workaround_work);
> > > + schedule_delayed_work(&twl->id_workaround_work, HZ);
> > > + return IRQ_HANDLED;
> > > + }
> > > +
> ... for example by this delayed work which is already there.
If we decide to keep this, it should be mod_delayed_work() I think.
Thanks.
--
Dmitry
