On Fri, Nov 13, 2015 at 03:13:41PM +0100, Daniele Palmas wrote: > 2015-11-13 11:58 GMT+01:00 Johan Hovold <johan@xxxxxxxxxx>: > > On Thu, Nov 12, 2015 at 02:55:04PM +0100, Bjørn Mork wrote: > >> I believe this supports the assumption that Infineon Flash Loader > >> devices have some ACM descriptors without actually being ACM class > >> devices, and that it is best to just collect them all in the > >> usb-serial-simple "flashloader" driver. > > > > I'm still not convinced. The device at hand does look and apparently > > behaves like a compliant ACM device, and I think we need to figure out > > why it does not work with this particular proprietary user-space tool > > before modifying the kernel. > > > > For example, using usb-serial-simple means that no line-control requests > > are sent. Perhaps the tool simply needs to set the termios settings to > > something else than the default 9600N81 that the cdc-acm driver uses. > > > > Modem control-requests would not be sent either (and HUPCL determines if > > DTR/RTS is lowered at close). > > > > Daniele, could you provide some more details about what happens when the > > proprietary tool fails. Do you have access to the sources? > > I'll try to explain how the whole thing should work. > Using the cdc-acm driver, the string, though being sent in the same > way than using the usb-serial-simple driver (I can confirm that the > data is passing properly since I used an hw usb sniffer), does not > make the device to stay in flashing mode. > > I thought that the problem was something done by the acm driver when > opening the port that is not accepted well by the flashing device on > the firmware side, so I tried also in the past to debug the driver, > but without success. > > I can start again to understand which is really the problem with > cdc-acm, but my fear is that to have a working solution with cdc-acm > will be more complicated (e.g. adding a new quirk) than adding support > in the usb-serial-simple driver. Consider also that this is not really > a communication device with subclass modem, as wrongly stated by the > usb descriptors, since it is simply a flashing device. > > Another interesting piece of the puzzle is that in Windows this device > requires a specific flashloader driver and does not use the acm driver > suggested by the vendor. Thanks for the details. I agree with you now, moving the device to usb-serial-simple makes sense. I'll take a look at these patches when 4.4-rc1 is out. Johan -- 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
