Re: Unreliable USB3 with NEC uPD720200 and Delock Cardreader

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On Thu, 25 Oct 2012, Ulrich Eckhardt wrote:

> Am 25.10.2012 03:24, schrieb Ming Lei:
> >> Lei, do you have any doc describing how to use those tracepoints?
> >
> > Hi Bjorn Helgaas,
> >
> > Firstly, please enable these tracepoints via below
> >
> >            echo 1 > /sys/kernel/debug/tracing/events/rpm/enable
> >
> > then store the trace event result by below once you make sure your interested
> > events are completed:
> >
> >            echo 0 > /sys/kernel/debug/tracing/events/rpm/enable
> >            cp /sys/kernel/debug/tracing/trace /media/ram/rpm-trace
> >
> Hi,
> 
> I have created a trace according this description. Therefore I have 
> rebooted my system, enabled the trace and inserted and removed the 
> SD-card until the controller stops working. During this procedure I 
> observed that the controller seems to be more stable. I had to insert 
> and remove the SD-card several times until the controller stopped 
> working. Normally the controller will fail on the first attempt. Also I 
> had the impression (not sure about this since I have not measured it) 
> that the card reader reads the data faster.
> 
> I append the gzipped trace and the corresponding dmesg output.

There's a much more straightforward way of telling when a PCI-based USB 
host controller gets suspended or resumed.  Just enable 
CONFIG_USB_DEBUG; then there will appropriate lines in the dmesg log.

Alan Stern

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