On Thursday 11 October 2012 11:05:05 Bjørn Mork wrote: > Bjørn Mork <bjorn@xxxxxxx> writes: > This is harmless because the driver ignores the sequence numbers anyway. > But if the disconnect on reset is typical for NCM devices, then I guess > it does not help much adding pre and post_reset in cdc_ncm. Nor does it hurt. > So I guess that demonstrates the issue with pre and post_reset on > devices keeping internal state pretty well: The effect is entirely > device dependent. The device reset behaviour is not known, and we risk > that the device changes some of its internal variables on reset. So > adding reset support to class minidrivers is risky. Although my > rndis_host test worked, there is no guarantee that other rndis devices > will work the same way. > > What do we do? Drop it? Add the support to usbnet and use it only where We want to do error handling well. That means we don't diminish support for good hardware because crap hardware can't do it. We don't break normal operation, but we are talking about error handling. Something is wrong away when we go down this code path. > "safe"? Add it and implement it in any minidriver using plain usbnet > suspend and resume, possibly adding device quirks later? We can add quirks later. > I believe qmi_wwan is a candidate for unconditional reset support > because all supported devices are based on the same chipset family using > the same chipset vendor firmware as a basis. And there is some benefit, > as these devices often expose a usb-storage interface in modem mode as > well. Go for it. Regards Oliver -- 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
