[bug #36740] FTDI USB Serial Device not recognized and "insmod ehci" freezes grub

[Ales Nesrsta]

Follow-up Comment #14, bug #36740 (project grub):

Hi Horst,

I probably found the cause of this bug.

I will prepare some experimental patch (soon - I hope) which You can try - if
You want.
I will make my own tests later when the ordered USB hub 1.1 will come to me
(it takes probably (very) long time...).

To Vladimir:

The problem is related to split transfer. EHCI needs address and port related
to FULL/LOW speed device connected to USB 2.0 hub which can do transaction
translation of split packets.

In Horst case it should be the address and port of USB 2.0 hub integrated in
PC where the ATEN KVM switch is connected (because ATEN is FULL speed device -
USB 1.1 hub with some special HID compound device connected to it, i.e. the
transaction transaction should be done in USB 2.0 hub in PC).

But GRUB uses (for split transfer) address and port of hub to which is target
device DIRECTLY connected - in Horst case it is address and port of ATEN USB
1.1 hub (which, of course, cannot do transaction translation...).
In another word, GRUB will fail in communication with any device which is
connected via USB 1.1 hub to USB 2.0 hub when USB 2.) hub is attached to EHCI
controller. This problem cannot happen on OHCI/UHCI controller.
I should rewrite whole logic which is related to "hubaddr" and "port" members
of grub_usb_device which I added together with EHCI.

BR,
Ales

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