On Thu, 19 May 2016, Andy Gross wrote:
> On 19 May 2016 at 05:12, Srinivas Kandagatla
> <srinivas.kandagatla@xxxxxxxxxx> wrote:
>
> <snip>
>
> > +++ b/drivers/usb/host/ehci-hcd.c
> > @@ -368,6 +368,15 @@ static void ehci_shutdown(struct usb_hcd *hcd)
> > {
> > struct ehci_hcd *ehci = hcd_to_ehci(hcd);
> >
> > + /**
> > + * Protect the system from crashing at system shutdown in cases where
> > + * usb host is not added yet from OTG controller driver.
> > + * As ehci_setup() not done yet, so stop accessing registers or
> > + * variables initialized in ehci_setup()
> > + */
> > + if (!ehci->sbrn)
> > + return;
> > +
> > spin_lock_irq(&ehci->lock);
> > ehci->shutdown = true;
> > ehci->rh_state = EHCI_RH_STOPPING;
>
>
> Should we also not check this in ehci_suspend and ehci_resume? If I
> do suspend/resume, it crashes in a similar manner. I know this goes
> beyond the problem scope of the patch. Perhaps I should send in an
> additional patch with the code?
>
> Are there any other places in the ehci-hcd where this needs to be checked?
Really, this is an indication that the problem lies not in ehci-hcd but
rather in the platform glue code. The platform code allows itself to
be registered as the driver of the controller device but does not
initialize the ehci-hcd parts.
Neither ehci_suspend nor ehci_resume is called directly by the driver
core; the calls all have to pass through the glue code. So maybe the
glue layer needs to be careful about invoking these routines in
ehci-hcd before ehci-hcd has been initialized.
Alan Stern
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