Hello Oliver, 2012/11/26 Oliver Neukum <oneukum@xxxxxxx>: > 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. > Ok. >> 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. > Ok. Do you have any hint for adding the code in the proper place? >> 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? > The doc is "Universal Serial Bus Specification" revision 2.0 paragraph 10.5.4.5, if I am not misunderstanding the topic. Here http://msdn.microsoft.com/en-us/library/windows/hardware/ff537628%28v=vs.85%29.aspx there is an interpretation coming from Microsoft "In USB terminology, a USB device is enabled for remote wakeup when its DEVICE_REMOTE_WAKEUP feature is set. The USB specification specifies that host software must set the remote wakeup feature on a device "only just prior" to putting the device to sleep." >> 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. Maybe I have to explain better my scenario: Modem is registered to the network. Host suspended, I want my device to wake up the host when it receives, for example, a call or an sms. This doesn't happen if the driver doesn't send the DEVICE_REMOTE_WAKEUP request. Moreover without this request the modem is bricked. I understand that probably there are problems in the firmware of the modem (because it should not brick), but I'm trying to find a workaround to have things working. > > Regards > Oliver > Thanks, Daniele -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
