On Tue, 31 Jul 2012, Kuninori Morimoto wrote:
> Hi Alan
> Cc Magnus, Rafael
>
> > > > this patch enable to use pm_runtime_xxx() on ehci-platform
> > > > if .config has CONFIG_PM_RUNTIME, otherwise, these are ignored
> > > >
> > > > Signed-off-by: Kuninori Morimoto <[email protected]>
> > > > ---
> > > > drivers/usb/host/ehci-platform.c | 6 ++++++
> > > > 1 files changed, 6 insertions(+), 0 deletions(-)
> > > >
> > > > diff --git a/drivers/usb/host/ehci-platform.c
> > > > b/drivers/usb/host/ehci-platform.c
> > > > index dfe881a..89029eb 100644
> > > > --- a/drivers/usb/host/ehci-platform.c
> > > > +++ b/drivers/usb/host/ehci-platform.c
> > > > @@ -122,6 +122,9 @@ static int __devinit ehci_platform_probe(struct
> > > > platform_device *dev)
> > > > if (err)
> > > > goto err_iounmap;
> > > >
> > > > + pm_runtime_enable(&dev->dev);
> > > > + pm_runtime_get_sync(&dev->dev);
> > >
> > > This line is peculiar. Why call pm_runtime_get_sync()? If the
> > > controller was at low power before, the usb_add_hcd() call above would
> > > have failed. If it was at full power before, this call isn't needed.
> > > Also it leaves the runtime PM usage counter set to 1, which will
> > > prevent the controller from runtime-suspending.
> > >
> > > I think what you want to do is more like this:
> > >
> > > pm_runtime_set_active(&dev->dev);
> > > pm_runtime_enable(&dev->dev);
> >
> > Thank you for explaining this.
> >
> > Indeed pm_runtime_xxx should be called befor usb_add_hcd()
> >
> > But on our system (= SuperH CPU), EHCI/OHCI device are
> > on-chip, and it needs power to use it.
> > So, we need to call pm_rumtime_get_xxx() to enable power.
> > Without this function, our EHCI/OHCI couldn't work.
> >
> > In this case, where should I call it ?
> > Or should I create new ehci-xxx driver ?
>
> I'm sorry for my confusing mail.
> I would like to say is "can I call pm_runtime_get_xxx() ?"
>
> pm_runtime_set_active(&dev->dev);
> pm_runtime_enable(&dev->dev);
> pm_runtime_get_xxx(&dev->dev);
>
> usb_add_hcd()...
The problem is that the ehci-platform driver currently doesn't know
anything about clocks or power sources. We need to add that
information in a generic fashion, somehow. Until that's done, you
can't really use ehci-platform as your driver.
So for example, if ehci-platform _did_ know about clocks and power
sources, then before calling usb_add_hcd() you would do:
ehci_platform_enable_clocks_and_power(dev);
pm_runtime_set_active(&dev->dev);
pm_runtime_enable(&dev->dev);
But you definitely cannot call pm_runtime_get_aync() or anything
similar, because the EHCI core resume routine assumes the controller's
clocks are already running and its power supply is at full power.
Can you figure out a good way to add clock and power information to the
usb_ehci_pdata structure? Something that will work with a large
variety of SoC EHCI controllers?
Alan Stern
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