Thanks to everyone who helped me with my first kernel patch. Please see the patch in the link below. If any revisions are necessary, please let me know. Thanks! http://sweetamandas.com/cp210x.patch.txt Signed-of-by: Blake Miner <bminer@xxxxxxxxxxxxxxxx> On Fri, May 16, 2014 at 10:08 AM, Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote: > On Fri, 16 May 2014, Miner, Blake wrote: > >> > I am not sure about this, but I wonder can we do the reset in >> > cp210x_open() instead of in cp210x_startup()? >> >> Possibly, but I'd rather perform the reset just once, right when the >> device is detected and bound to the driver. After doing some more >> reading, I've found that calling `usb_lock_device_for_reset` just >> before `usb_reset_device` seems to work. Here's a possible patch: >> >> --- cp210x.c >> +++ cp210x.c.new.c >> @@ -856,7 +856,8 @@ >> struct cp210x_serial_private *spriv; >> >> /* cp210x buffers behave strangely unless device is reset */ >> - usb_reset_device(serial->dev); >> + if(usb_lock_device_for_reset(serial->dev, NULL) == 0) >> + usb_reset_device(serial->dev); >> >> spriv = kzalloc(sizeof(*spriv), GFP_KERNEL); >> if (!spriv) >> >> The downside here is that the reset takes a few hundred extra >> milliseconds, and the reset is issued for each interface. But, at >> least both interfaces are properly detected the first time. :) Any >> thoughts? > > If you lock a device, you have to unlock it later. Read the kerneldoc > in the definition of usb_lock_device_for_reset() to see how it works. > > Alan Stern > -- 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
