[Bug 220748] usb: xhci_queue_isoc_tx_prepare ignore start_frame and always assumes URB_ISO_ASAP is set

[bugzilla-daemon@kernel.org]

https://bugzilla.kernel.org/show_bug.cgi?id=220748

--- Comment #22 from Nicola Lunghi (nick83ola@gmail.com) ---
(In reply to dylan_robinson from comment #20)
(In reply to Michał Pecio from comment #21)
Hi Dylan, Michal
I just want to report that with the patches I've submitted to the kernel the
issue with clock synchronization with the motu is gone and the interface is
super stable.
I've tested the interface running continuosly playing 12 audio channels
connected to an usb 2 hub (via another hub) while strees testing the usb
connection using fio on a separate usb disk on the same hub

Running kernel 7.1.0-rc2 with the patches applied, I can start and restart
playback repeatedly without any channel desync. usbmon confirms the frame
numbers are now perfectly sequential throughout — every
  URB completion on EP 0x09 OUT comes back status 0 with start_frame
incrementing by exactly +8, no gaps, no EXDEV. I've set the motu at 16 samples
buffer / 16 samples host safety and is still rock solid. 

I've implemented another patch to do a channel reinizialization if the driver
detect gap in the packets (that would break the synchronization) but on my
system I cannot trigger it. I think at this point is probably not needed. I'll
attach the extra patches to this post so you can have a look

Thanks,
Nicola

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