On 20 May 2016 at 09:31, Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote:
> 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.
That's a good point. Perhaps all of this should be in the glue,
including the shutdown case.
Regards,
Andy
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