Re: Errata for Freescale root-hub TT?

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On Tue, 24 Mar 2015, Peter Chen wrote:

> On Mon, Mar 23, 2015 at 10:11:04AM -0400, Alan Stern wrote:
> > On Mon, 23 Mar 2015, Peter Chen wrote:
> > 
> > > For going on debugging this problem, we need
> > 
> > I will have the hardware only for one more day, so I may not be able to
> > get all the information you want.
> > 
> > > - Your bus analyzer file, I think there should be no enough IN/OUT
> > > tokens within one frame, does the remaining time to frame boundaries
> > > is enough? 
> > 
> > Here's an example: There are four OUT transfers near the start of the 
> > frame, and they take about 300 us.  The remaining 700 us in the frame 
> > are completely idle, even though they should contain four IN transfers.
> 
> How do you know the frame has filled already at that time? The software
> makes sure it fills frame in time before next time frame?

I'm not sure I understand the question.

The USB analyzer log showed something like this (this is a rough 
approximation because I didn't keep the original analyzer output file):

	Timestamp		Transaction
	s.mmm uuu
	-----------------------------------
	0.000 000		SOF
	0.000 030		Isoc OUT
	0.000 091		Isoc OUT
	0.000 162		Isoc OUT
	0.000 224		Isoc OUT
	0.001 000		SOF

In this example, there are 4 OUT transfers taking about 290 us and then
nothing else for the rest of the frame.

I also know, from looking at the "periodic" file in the EHCI debugfs 
directory, that each frame was linked to 8 siTDs:

	siTD OUT, Smask = 0x01, Cmask = 0x00, transfer length = 64
	siTD OUT, Smask = 0x01, Cmask = 0x00, transfer length = 64
	siTD OUT, Smask = 0x02, Cmask = 0x00, transfer length = 64
	siTD OUT, Smask = 0x02, Cmask = 0x00, transfer length = 64
	siTD IN,  Smask = 0x04, Cmask = 0x70, transfer length = 64
	siTD IN,  Smask = 0x04, Cmask = 0x70, transfer length = 64
	siTD IN,  Smask = 0x08, Cmask = 0xe0, transfer length = 64
	siTD IN,  Smask = 0x08, Cmask = 0xe0, transfer length = 64

Alan Stern

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