[Bug 207219] [BISECTED] Sony Vaio laptop built-in ricoh webcam no longer found on Fedora 31 with 5.4.11 kernel

[bugzilla-daemon@bugzilla.kernel.org]

https://bugzilla.kernel.org/show_bug.cgi?id=207219

Alan Stern (stern@rowland.harvard.edu) changed:

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                 CC|                            |stern@rowland.harvard.edu

--- Comment #10 from Alan Stern (stern@rowland.harvard.edu) ---
It won't slow down enumeration all that much.

If you had a problem then it's likely that a bunch of other people had the same
problem too; they just didn't bother to report it.  Fixing your system will
help all those other people as well -- certainly it should help anyone who has
the same kind of laptop with the same kind of camera.  (Unless the problem was
a hardware flaw in your webcam, not any others.)

In theory we could add another usbcore module parameter for this.  But in fact,
usbcore already has too many module parameters; adding new ones is discouraged.
 Besides, that sort of thing isn't guaranteed always to work.  Some devices
will want the old scheme to come first, and others (like your webcam) will want
the new scheme to come first.  What can you do if your system has both types of
device present?

If you really want to track this down farther, here's something you can try. 
Set up your system so that the ehci-pci driver doesn't get loaded
automatically, in either the running system or the initrd image.  Then when the
system has started up, start up a usbmon trace from the 0u file (that is, all
buses) and load ehci-pci manually.  That way we can see exactly what happens
when the webcam gets initialized for the first time.

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