On Mon, 16 Jul 2012, Ingo Rohloff wrote:
> Hello,
>
> I have some problems with an ASM1042 SuperSpeed Host Controller.
> (IvyBridge + PantherPoint Motherboard).
> I also read some comments that this particular Host Controller might have
> some problems, but I could
> not find any details.
> Each URB tries to read up to 0x4000 bytes from Endpoint 0x85.
> The device should send 0x2FFE bytes.
> My assumption was, that every 12th packet only contains 0x3FE bytes and thus
> stops the currently
> active URB.
>
> It seems the ASM1042 sometimes does not stop the transfer after receiving a
> short packet, or at
> least the URB continues (stopping after 16KByte).
>
> QUESTION: Is this a known problem or am I doing something wrong ?
See
http://marc.info/?l=linux-usb&m=134236551409964&w=2
Apparently the ASM1042 reports that a transfer completed normally even
when it was short (or when it was cancelled).
xHCI controllers in general do not stop transfers after receiving a
short packet. Apparently there's no way to tell them to stop under
those circumstances.
Alan Stern
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