[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



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