On Monday 26 November 2012 10:42:48 Daniele Palmas wrote:
> Hello,
>
> I'm using the modem Telit HE910 with cdc-acm driver.
>
> I've found that after a suspend and resume of the operating system
> (e.g. pm-suspend), the modem does not answer anymore.
>
> Collecting logs with an usb sniffer, it seems that, unlike the Windows
> driver, the host does not send the packet SET_FEATURE DEVICE_REMOTE
> WAKEUP, needed by the modem.
This is a new quirk.
> I've added few lines of code (in the acm_suspend function) for sending
> this packet and now things work.
acm_suspend is definitely not the place to put this, even if it fixes
your particular usage.
> According to the USB 2.0 specs it seems to me that this feature should
> be always requested when suspending a device, so probably the driver
> behavior is not correct.
Hm. Which part of the spec do you base this on?
> Does cdc-acm really not support this feature or am I missing some
> configuration parameters that enable the sending of this request?
For a modem this feature makes relatively little sense. I've never
seen a modem that doesn't hang up when you suspend it.
Regards
Oliver
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