Re: [Patch] Increase USBFS Bulk Transfer size

Alan Stern
2011-10-16T14:18:30Z

On Sun, 16 Oct 2011, Johannes Stezenbach wrote:

> On Sat, Oct 15, 2011 at 03:04:28PM -0400, Alan Stern wrote:
> > On Sat, 15 Oct 2011, Johannes Stezenbach wrote:
> >
> > > What I meant to say is Markus' statement that the device only
> > > works at a certain transfer size cannot be true since
> > > this size is not visible to the device via the USB bus.
> >
> > That's what I would expect, too. But did you take a look at the usbmon
> > traces Markus acquired?
> >
> > http://marc.info/?l=linux-usb&m=131845614819045&w=2
>
> I glanced at them for 3 seconds, but I cannot be bothered
> to analyze them in detail. The ASCII usbmon traces don't
> show full USB packet contents anyway so you can't see if
> partial MPEG TS packets are missing.

> The device transfers data in the "not working" case, it's just that
> the MPEG TS sync byte is not where Markus expects it, which could
> be explained by a partial MPEG TS packet left in the device's FIFO
> from previous interaction.

But why does this happen only when the transfer size is different from
24064? Why doesn't it also happen when the transfer size _is_ 24064?

Alan Stern