On 08/06/14 08:34, Dan Mahoney wrote:
On Wed, 6 Aug 2014, Hans Petter Selasky wrote:
On 08/06/14 01:50, Peter Losher wrote:
(please include my and Dan's email in any responses as we normally don't
lurk on the USB mailing list)
So @work we use serial->USB TTY MUX's to handle our serial console needs,
and at some sites we have a need that is greater than a single 16 port
device (the max you can get). The problem is that with two of these 16 port
USB devices is that sometimes during a reboot that the "second" device gets
probed first and so the first 16 and second 16 /dev/ttyU* blocks swap
around... which of course plays havoc with any symlinks we have to the
devices in rtty or conserver. :(
Is there any way to tell the USB code to always select a certain device
first? I assume this has been a issue with USB storage devices so this
shouldn't be a new issue. And I tried searching for a answer on the web to
no avail.
Ideas?
Hi,
USB enumerates in sequential order, but sometimes devices might not be ready
to enumerate, and then a port is skipped.
Does the device have a serial number?
usbconfig -d X.Y dump_device_desc |grep iSerial
If yes, this can be filtered by a devd rule, when the device attaches, and
then you can switch the serial number to create any symbolic links.
Curiously, it looks like one of our two usb-to-serial devices (both are
16-port devices), presents as 16 separate USB devices, and the other
presents as clusters of four:
iSerialNumber = 0x0003 <FTWVV6Z7>
iSerialNumber = 0x0003 <FTWVV70Y>
iSerialNumber = 0x0003 <FTWVV72I>
iSerialNumber = 0x0003 <FTWVV74C>
iSerialNumber = 0x0000 <no string>
iSerialNumber = 0x0003 <ST160898>
iSerialNumber = 0x0003 <ST160897>
iSerialNumber = 0x0000 <no string>
iSerialNumber = 0x0003 <ST160900>
iSerialNumber = 0x0003 <ST160899>
iSerialNumber = 0x0003 <ST160902>
iSerialNumber = 0x0003 <ST160901>
iSerialNumber = 0x0003 <ST160904>
iSerialNumber = 0x0003 <ST160903>
iSerialNumber = 0x0003 <ST160906>
iSerialNumber = 0x0000 <no string>
iSerialNumber = 0x0003 <ST160905>
iSerialNumber = 0x0003 <ST160908>
iSerialNumber = 0x0003 <ST160907>
iSerialNumber = 0x0003 <ST160910>
iSerialNumber = 0x0003 <ST160909>
iSerialNumber = 0x0003 <ST160912>
iSerialNumber = 0x0003 <ST160911>
However, if I understand you correctly, not-ready issues aside, what we
really need to do is to ensure that our devices are simply plugged into
USB ports that are probed in the correct order, and assuming they're all
ready to probe, this shouldn't be a problem.
What I think happened here was that one of these devices was added to
an earlier-sequenced port after bootup.
Of course, from the back of a server, it's totally non-obvious what the
sequence is. Is there an easy way to tell where in the probe sequence a
given port will be?
-Dan
Hi,
Ports are probed 1,2,3,4, if they are labeled as such.
When adding new equipment, you can force a re-enumeration of the root
HUB, where the devices are attached, and then the order shall be the
same as at reboot:
usbconfig -d X.1 set_config 255
usbconfig -d X.1 set_config 0
If the devices are attached to different USB controllers there is no
guarantee about the probe order.
--HPS
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