On Fri, Aug 08, 2014 at 03:10:34AM +0800, Wang YanQing wrote: > On Tue, Aug 05, 2014 at 03:54:08PM +0200, Johan Hovold wrote: > > > > I noticed that setting direction to output and setting the gpio high has > > > > no effect on the read-back value (i.e. I still read back 0) for my > > > > pl2303hx (note that my device has no easily accessible gpios so I > > > > haven't verified the actual state of the output pin). > > > > > > > > What happens on your system? Is the read-back value still 0, even when > > > > the GPIO output is actually high? Should we return the cached value in > > > > this case? > > > > > > If i set direction to output, then I could control gpio high and low > > > by set 1 or 0, and the read-back value is 1 or 0 according to high and > > > low(I test high and low by oscillscope) > > > > > > I test it with my pl2303hx with only two gpios. > > > > > > Could you use usbmon to see whether the traffic is right according > > > to comment in struct pl2303_gpio? > > > > The traffic appears correct judging from the debug output (which I > > trust). Output-enable is reflected in register 0x81, but the value > > isn't. > > > > What is the lsusb -v output for your device? > > Bus 001 Device 005: ID 067b:2303 Prolific Technology, Inc. PL2303 Serial Port. You forgot the verbose flag (-v). > It is strange your device doesn't work, I verify the control method by > analyze usbmon output from linux host which has VirtualBox running > gpio test program, but I don't have right to distribute the gpio test > program I think, so I can't help you to figure out why it doesn't work > for your device. What do you use the gpio test program for? I thought you verified the gpios with a scope? Perhaps mine just does not support GPIOs? I don't know, but that's partly why I asked for the lsusb output. Apparently there's a bunch of different versions of these chips out there. I'll see if I can find time to dissect my converter and try to access the GPIO pins with the next version of the patch. > > I suggest you just set the label to pl2303 until we have a valid > > use-case that requires something more elaborate. > > Ok, but pl2303-gpio maybe a better name? No, not really. It's a gpio-chip label and is only used in that context so a "-gpio" suffix adds no information. Thanks, 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
