Hi,
On Thu, Aug 13, 2015 at 01:37:19PM -0500, Felipe Balbi wrote:
> Hi,
>
> I have reproduced this write failure very reliably with two different
> hosts (my xHCI Desktop and AM335x with MUSB).
>
> It's very simple to reproduce with the ruby script below:
>
> #!/usr/bin/env ruby
>
> 1000000.times do |amt|
> File.open("/dev/ttyUSB0", 'w') do |write|
> str = "a" * (amt + 1)
> puts "writing #{str.length} bytes to #{write.path}"
> write.puts str
> end
> end
>
>
> Basically, CP2108 stops sending data and starts NAKing any IN tokens
> from the host. Attached you can find a fresh sniffer capture of the
> problem reproduced with AM335x running today's linux-next.
>
> To read the sniffer capture, you'll need DataCenter SW which can be
> downloaded from [1] (there are binaries for Windows, Linux and Mac.
> You'll need gstreamer0.10 to run).
>
> There are ways to make it behave. If I add a reading thread reading from
> ttyUSB1 with a null modem cable routed from ttyUSB0 to ttyUSB1, then it
> works. It also works by adding a sleep or enough debugging messages.
>
> Let me know if you need any extra information to reproduce this problem.
>
> Attached you can also find a screenshot with a snipet of the sniffer
> capture showing the timed out control transfer and a little context
> around it.
>
> [1] http://www.totalphase.com/products/data-center/
resending without attachments, you guys already got it anyway :-p
--
balbi
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