Re: Linux 3.8-rc1 - another regression on USB :-(

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Alan Stern wrote:
On Tue, 15 Jan 2013, Woody Suwalski wrote:

Another important change is that the EHCI driver is now split into two
modules.  That can slow down loading and affect the timing.

Alan Stern

My testcase is a live initramfs + squash root.
The boot logic is as stable as can be - unchanged since 2.6.2x kernels.
And it was working fine till 3.8-rc1.

The modules are insmoded in a fixed order:
usb-common, usbcore, xhci-hcd, ehci-hcd, uhci-hcd, ohci-hcd, usbhid,
usb_storage,...
But apparently you don't insmod ehci-pci.  That could cause problems,
if your EHCI controller is PCI-based.

If all USB is built as modules - I get read errors from USB drives when
accessing squash image, boot fails.
What read errors?  What is the cause of these errors?

If usb-common and usbcore are built in, system seems to crawl with a
very slow USB, but boots. That could be caused by timing between hcd
modules.
Do have a dmesg log with timestamps so we can see where things go slow?
I suggest enabling CONFIG_PRINTK_TIME and CONFIG_USB_DEBUG.  You might
even want CONFIG_USB_STORAGE_DEBUG, although that often logs too much
information.

If usb-common, usbcore and ehci-hcd are built-in, all works OK like
"before 3.8".
What about ehci-pci?


Alan, it took me 2 times re-reading the email to notice...
You were talking about ehci-pci, not ehci-hcd... Old assumptions die hard...
Yep, that was it.
Catch22 - I would have noticed new dependency if I could boot, but to boot I have had needed to notice the new dependency...

Case solved 8-)

Thanks, Woody

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