[Bug 220033] xhci: Compliance Issue - avg_trb_len not set for EP0 during Address Device Command

[bugzilla-daemon@kernel.org]

https://bugzilla.kernel.org/show_bug.cgi?id=220033

Michał Pecio (michal.pecio@gmail.com) changed:

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                 CC|                            |michal.pecio@gmail.com

--- Comment #3 from Michał Pecio (michal.pecio@gmail.com) ---
(In reply to Chen-Tzu-Chieh from comment #0)
> Some xHCI hardware vendors may validate the Input Context at Address Device
> time and reject contexts with invalid values, potentially causing device
> enumeration issues.
A scarier (and more likely?) possibility is HCs failing to validate this field
and yet assuming that it's non-zero, then dividing by zero or doing some other
stupid thing and crashing and burning. Bonus if it only happens once in a blue
moon.

But as Mathias found, the spec is self-contradictory, so it works both ways...

> While xhci_endpoint_init() later sets avg_trb_len correctly,
Are you sure? ;)

This function is only called from add_endpoint(), which doesn't seem to ever be
called on EP 0. But non-default control endpoints would be set to 8 indeed.

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