[Bug 214021] The USB devices fail to be detected during boot

[bugzilla-daemon@bugzilla.kernel.org]

https://bugzilla.kernel.org/show_bug.cgi?id=214021

--- Comment #3 from Alan Stern (stern@rowland.harvard.edu) ---
You can try changing the bPwrOn2PwrGood value in the kernel source to see if
that will make any difference.  The line to change is in
drivers/usb/host/xhci-hub.c in the function xhci_common_hub_descriptor().  It's
at the start of the function:

        desc->bPwrOn2PwrGood = 10;      /* xhci section 5.4.9 says 20ms max */

The value gets multiplied by two, so if you change it to 50 then the delay will
become 100 ms.

However I suspect that the length of this delay is not the cause of the problem
you see.  The actual error occurs in the usb_alloc_dev() function in
drivers/usb/core/usb.c.  You can try adding some printk statements in there to
see which of the "return NULL" statements is the one you're getting.

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