USB host on Ingenic CPUs

Xiangfu Liu xiangfu at
Sat Sep 8 10:42:08 EDT 2012


I forward this message to Ingenic people. I will let you know
if they reply.


On 09/08/2012 07:45 PM, Daniel Glöckner wrote:
> Hi,
> for analyzing the problems observed with a cheap no name USB serial
> adapter in combination with my JZ4730 based Letux 400, I triggered
> an oscilloscope once the OHCI controller aborts an URB with an error.
> The capture clearly shows several NACK'ed IN transactions followed by
> a single IN transaction without response from the USB device.
> The error counter in the transfer descriptor had the value 3.
> Here the missing response is not the problem. The problem is that
> the USB spec states that transactions must be aborted after three
> errors _in_a_row_. I suspect that the Ingenic OHCI controller fails
> to reset the error counter on a NACK'ed transaction.
> Can anyone confirm my observations?
> What about other Ingenic chips?
>    Daniel
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