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SubjectRe: [PATCH] usb: echi-hcd: Add register access check in shutdown
On Wed, 18 May 2016, Srinivas Kandagatla wrote:

> On 18/05/16 15:56, Alan Stern wrote:
> > This doesn't seem like the right place. What you really should do is
> > skip calling ehci_silence_controller() if the hardware isn't
> > accessible. That's where the hardware gets touched, not in
> > ehci_shutdown().
>
> Just tried this suggestion, this would not work as well, Its not just
> the hardware registers, which are of concern here, but also the rest of
> the things like ehci->hrtimer pointer which are allocated or initialized
> as part of ehci_setup().
>
> Either the msm controller driver is not correct or we should have a way
> to stop calling ehci_shutdown() if there was no ehci_setup() done yet.
>
> Any suggestions?

Yes, you're right.

Since you're concerned about more than just accessing the hardware
registers, HW_ACCESSIBLE isn't the right thing to test. You need
something that gets set in ehci_setup() and nowhere else.

One possibility is ehci->sbrn. If that is equal to 0 then ehci_setup()
hasn't run, so ehci->shutdown() can simply return. Be sure to put a
comment in the code explaining the reason for doing this.

Alan Stern

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