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

[Woody Suwalski]

Alan Stern wrote:
> On Sat, 12 Jan 2013, Andreas Mohr wrote:
>
> > There's of course the EHCI vs. UHCI(/OHCI) duality
> > (EHCI host controller responsible for high speed transfers,
> > the other for 1.1 full speed, both serving the same port connectors).
> > So if the coordination between the two is a problem,
> > you might end up with merely full speed on a 2.0 port.
> >
> > And with drivers builtin vs. module, the init sequence/timing
> > might possibly be affected - right?
> > Perhaps this got worsened by semi-recent driver init kernel changes?
> > (AFAIR the kernel was changed to init more things in parallel,
> > for faster bootup). So maybe that affected EHCI vs. UHCI coordination timing.
> 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,...

If all USB is built as modules - I get read errors from USB drives when 
accessing squash image, boot fails.
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.
If usb-common, usbcore and ehci-hcd are built-in, all works OK like 
"before 3.8".
I was testing on machines  without xhci or ohci hardware, so these 
drivers probably are not playing any role.
I have retried initramfs with a 1s sleep between insmods to verify if it 
is timing - still the same read errors - so the main issue is _not_ timing.
The read errors problem is 100% reproducible for me, the blocks where 
read fails are not fixed - every (failed) boot errors start appearing in 
a bit different location.
Just selecting a differently - configured  kernel image makes the boot 
work, so it is not a problem of squash image, USB drive, squashfs driver.

Scratching my head loudly,
Woody

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