[FHZ] [EM] Occassionally very slow response from EM1010 (perhaps 2.6.31 ftdi_sio issue?)

[Guest]

Originally posted by: <email address deleted>

Hi,

I'm running fhem on my x64 Ubuntu 9.10 house server. Connected to it
are a FHZ1000 (via remserial, physically connected to a remote AP
running DD-WRT) and a EM1010 (via direct physical connection, ttyUSB2)

Everything basically works fine. Recently, however, I've started to
notice that requests to the EM1010 occassionally take an excessive
amount of time, sometimes over two minutes. Example:

Bad request:

2010.01.06 12:25:06 4: EM: Sending 02001002007a00aae103
2010.01.06 12:27:48 5: EM: returned
06002603000001c62300003b420a001401800ca62c9a2c862200009d2c9d2c9d2c14010000e50c0000c623000012ff1b08ee02

Good request:

2010.01.06 12:27:48 4: EM: Sending 02001002007a04b16103
2010.01.06 12:27:50 5: EM: returned
8c002703000002232b00007e161b005c00000e272b1b2b872100001e2b1e2b1e2bac070000690f0000232b00002900dc050000

This seems to happen at about 1/5 of all requests. After adding some
debug code to 60_EM.pl, it appears that bytes are read at a rate of
1-2 per second if the problem happens.

I'm seeing this effect with both fhem 4.8 and 4.6, and also with
em1010.pl. I strongly suspect that this started to happen when
upgrading the server from Ubuntu 9.04 to 9.10, but I'm not 100% sure
due to a too low log level in the old logs and no easy way of
downgrading the system to test with a 2.6.28 kernel.

I've read a lot about bugs in ftdi_sio introduced in 2.6.31, i.e.
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/460857 --
however, neither the backport proposed in the bug report nor upgrading
to 2.6.31-17 (from proposed) fixed the issue for me. Also, two other
ftdi_sio-Devices (FT232, though) connected to the box work fine.

Is anyone else seeing this effect? What are normal response times for
the EM?

Thanks!

Best Regards,
Olli

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