On 06.12.2011 22:24, Alan Stern wrote:
On Tue, 6 Dec 2011, Sancho Dauskardt wrote:
On 06.12.2011 09:40, Andiry Xu wrote:
[..]
What also really bugs me, is that the hub between the root-hub and
usb-storage device really makes a difference.
Monitoring the link between hub and root hub never showed any bad
packets but still there is packet loss upstream with the hub and none
without.
Did you try monitoring the link between the hub and the device? Did
the packets look the same from that viewpoint?
Yes, checked that and it seemed the same pattern.
But I havent got the equipment to monitor both links in parallel.
We want to retry with a mainboard from a different vendor next.
Could the hub be changing the timing in some minor way that breaks the
root hub ?
I don't know about changing the timing. It certainly could change the
other electrical characteristics (voltage and so on).
You may have mentioned this before, but I don't remember: Did you try
using other brands of hubs?
Yes, one Cypress hub has the same problem, the older SMSC hubs (250x)
are ok, and a NXP is ok to.
Thanks,
- sda
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