ohci: USB devices only detected at boot time

[Raphael Assenat <raph@8d.com>]

Hello,
I have some pxa270 based single board computers which have an 
IT8152G companion chip. This chip has a built-in USB Host controller 
which is (according to the datasheet) register compatible with OHCI 
specification version 1.0.

During boot, I see that the OHCI controller is detected properly. 
Devices that were already connected to the USB ports handled by this 
chip are also detected at boot time. And they work correcly.

But when I connect a new device to a free port, nothing happens. No 
messages in dmesg, and the device does not seem to initialize. (eg: 
Led under optical mouse does not turn on). I have verified, and 
there is power on the USB power pins. If I disconnect a device that 
was present at boot time and reconnect it, it is not re-detected.

Here is a list of kernel version I was able to test with, and the 
results:
2.6.20 -> Same problems as described above.
2.6.18 -> Same problems as described above.
2.6.17.5 -> Same problems as described above.
2.6.16.12 -> Everything works fine.

Suspecting that this could be a bug in the chip's implementation 
exposed by some new features, I started looking at the code in the 
hope to find stuff like controller specific work arounds, quirks, 
etc to try. but I found nothing that was applicable to my problem...

I eventually decided to try the modification below, and now it works 
correctly! But I dont understand why as I have very little knowledge 
on the subject.

Any ideas?

--- linux-2.6.20/drivers/usb/host/ohci-hub.c
+++ linux-2.6.20-8d/drivers/usb/host/ohci-hub.c
@@ -413,7 +413,7 @@
  {
     struct ohci_hcd *ohci = hcd_to_ohci (hcd);
     int     i, changed = 0, length = 1;
-   int     any_connected = 0;
+   int     any_connected = RH_PS_CCS;
     unsigned long   flags;

     spin_lock_irqsave (&ohci->lock, flags);


Detection messages:
ohci_hcd: 2006 August 04 USB 1.1 'Open' Host Controller (OHCI) 
Driver (PCI)
ohci_hcd 0000:00:01.4: OHCI Host Controller
ohci_hcd 0000:00:01.4: new USB bus registered, assigned bus number 2
ohci_hcd 0000:00:01.4: irq 167, io mem 0x10000000


Best regards,
-- 
Raphael Assenat
8D Technologies Inc.

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