[PATCH 1/1] fix occasional ULPI timeouts with ehci-mxc
Andy Green
andy at warmcat.com
Wed Dec 2 14:35:33 EST 2009
On 12/02/09 18:58, Somebody in the thread at some point said:
Hi -
> mx27# usb 2-1: new low speed USB device using mxc-ehci and address 2
> hub 2-0:1.0: unable to enumerate USB device on port 1
>
> What you think about it?
What did you do with your chip select line on the ULPI PHY?
The first iMX LiteKIT board I had was an old revision where they had
tied the PHY chip select pin asserted. The ULPI PHY acted braindamaged
because glitchy junk from during poweron / reset was taken as real data
and it never recovered during the session.
Later versions of the LiteKIT changed this to be pulled deasserted and a
GPIO can drive it asserted after reset is all done. After I got a later
revision with that mod, and drove the GPIO, suddenly all was well.
Never going to get that week back though.
-Andy
More information about the linux-arm-kernel
mailing list