Problem with full speed devices on PowerPC MPC5121 host port

[Anatolij Gustschin]

Hi Matthias,

On Tue, 17 Jan 2012 15:12:50 +0100
Matthias Fuchs <matthias.fuchs at esd.eu> wrote:

> On 06.01.2012 19:03, Alan Stern wrote:
> > On Fri, 6 Jan 2012, Matthias Fuchs wrote:
> > 
> >> For my eyes it does not really look like a general USB issue.
> >> It looks like a problem with the Freescale EHCI implementation that is
> >> influenced by high interrupt or internal bus load caused by the flood ping.
> > 
> > Indeed, it might be a problem with the built-in Transaction Translator.  
> > That would explain why it affect full-speed devices.
> > 
> > However, I would expect the resetting the controller hardware (which 
> > happens when you reload the ehci-fsl driver) would fix any such issues.  
> > It's hard to imagine how a problem could survive a reset like that.
> 
> I did the tests again. When the error occured I reloaded the ehci-hcd driver and reconnected the device. It ends up with some kernel messages 
> that come up time after time:
> 
> usb 1-1: new full-speed USB device number 2 using fsl-ehci
> usb 1-1: device descriptor read/64, error -110
> usb 1-1: device descriptor read/64, error -110
> usb 1-1: new full-speed USB device number 3 using fsl-ehci
> usb 1-1: device descriptor read/64, error -110
> usb 1-1: device descriptor read/64, error -110
> usb 1-1: new full-speed USB device number 4 using fsl-ehci
> usb 1-1: device not accepting address 4, error -110
> usb 1-1: new full-speed USB device number 5 using fsl-ehci
> usb 1-1: device not accepting address 5, error -110
> hub 1-0:1.0: unable to enumerate USB device on port 1
> 
> A recommondation from freescale was to check the TXFILLTUNING register settings ("Initialization of this registers can produce problem if full-speed device is used").
> 
> So I tried various values in the TXFILLTUNING register (I added this
> code to ehci_reset()). Finally I disabled USB streaming mode in the USBMODE register (set bit USBMODE_SDIS - btw., it should be defined as "1 << 4" in ehci_def.h at least for the MPC5121).
> 
> All this does not fix the problem or even have an impact.

Can you try the attached patch? Does it have an impact?

Best regards,
Anatolij
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