[SeaBIOS] USB-to-SATA bridge conflicts with USB boot flash drive

[Аладышев Константин]

Hello!

I use coreboot+SeaBIOS bundle on custom motherboard with Intel Haswell i7
and Lynxpoint-LP chipset and I've come to a strange issue with USB-to-SATA
bridge TUSB9261 (http://www.ti.com/product/TUSB9261).
In my experiments I plug HDD to one USB port, and USB boot flash drive to
another USB port.
Everything works fine when HDD is present on USB-to-SATA bridge. SeaBIOS
displays both devices in its boot menu. But if HDD is not present and if USB
boot flash drive is plugged to a port greater than USB-to-SATA bridge port,
SeaBIOS doesn't see flash drive as bootable device.

In this case I see in log messages similar to this:
"""
Searching bootorder for: /pci at i0cf8/usb at 1d/hub at 1/storage at 7/*@0/*@0,0
Searching bootorder for: /pci at i0cf8/usb at 1d/hub at 1/usb-*@7
ehci_send_pipe qh=0x000eab80 dir=0 data=0x00006b79 size=31
ehci_send_pipe qh=0x000eab00 dir=128 data=0x00006c98 size=36
WARNING - Timeout at ehci_wait_td:516!
ehci pipe=0x000eab00 cur=000069c0 tok=80240d80 next=1 td=0x000069c0
status=240d80
USB transmission failed
Unable to configure USB MSC drive.
phys_free f4950 (detail=0x7f6c13c0)
Unable to configure USB MSC device.
"""

Summarizing all the above with SeaBIOS logs:

SeaBIOS displays flash drive correctly as bootable device when:
- HDD is present on SATA-to-USB port (https://pastebin.com/SuKBkQrq)
- HDD is not present on USB port, but SATA-to-USB port number is greater
than USB flash drive number (https://pastebin.com/9f6RTBHB)

SeaBIOS doesn't display flash drive as bootable device when:
- HDD is not present on USB port and SATA-to-USB port number is less than
USB flash drive number (https://pastebin.com/abBPhej0)


What can be the source of the problem and what can I do to solve this issue?

Best Regards,
Aladyshev Konstantin