On Tue, 19 Sep 2006, Jiri Kosina wrote:
> On Mon, 18 Sep 2006, David Brownell wrote:
>
> > > EHCI, UHCI and OHCI USB host drivers are not consistent when returining
> > > error values from their _suspend() functions, in case that the device is
> > > not in suspended state. This could confuse users, so let all three of them
> > > return -EBUSY.
> > Shouldn't you also update uhci_suspend()? Currently it just ignores
> > hcd->state ...
>
> You are right that the patch is possibly not fully correct. I was trying
> to fix the situation I was getting into with the bug in usb_resume_both()
> (see my "[PATCH] 2.6.18-rc6-mm2 - usb_resume_both() - fix suspend/resume"
> mail from yesterday), but now it is obvious that the EINVAL from UHCI is
> of a "different kind" than EBUSY from OHCI and UHCI (though they are
> triggered in the same situations -- when the previous resume was not done
> correctly).
Sort of. The real trigger is that the PM core tries to suspend the
upper-level PCI device but the lower-level root-hub device has not been
suspended. You saw this occurring because during the previous resume, the
root-hub device's power.power_state.event was not updated, causing the PM
core to think the root hub was still suspended when in fact it wasn't.
> As far as I can see, the UHCI driver is, strangely enough, not using
> hcd->state at all.
>
> (by the way, EHCI and OHCI seem to have broken (read: missing) locking
> when accessing the hcd->state. Should I fix it by per-hcd spinlock, or
> does the patch already exist somewhere?)
Believe it or not, these two paragraphs are closely connected. The reason
uhci-hcd doesn't use hcd->state at all is because there is no locking to
protect it!
My feeling has long been that hcd->state deserves to disappear. It tries
to serve too many functions. Please don't add any code in a futile
attempt to preserve it.
Alan Stern
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
