On Sat, 29 Feb 2020, Noralf Trønnes wrote:
+static void mud_irq_urb_completion(struct urb *urb) +{
- struct device *dev = &urb->dev->dev;
- int ret;
- mdebug("%s: actual_length=%u\n", __func__, urb->actual_length);
- switch (urb->status) {
- case 0:
mud_irq_queue(urb);break;- case -EPROTO: /* FIXME: verify: dwc2 reports this on disconnect */
What does this mean? Why can't you fix it now?
I don't know if this is a dwc2 driver problem or if EPROTO is a valid disconnect error. I haven't seen it in other gadget drivers, so I need
Note: This is not a gadget driver. You should be looking in device drivers.
to look more into this or even better if someone from USB can answer this.
See Documentation/driver-api/usb/error-codes.rst. In short, -EPROTO is one of several status codes you may get when an URB fails because the device was disconnected.
- case -ECONNRESET:
- case -ENOENT:
- case -ESHUTDOWN:
dev_dbg(dev, "irq urb shutting down with status: %d\n", urb->status);s/irq/IRQ/ in all comments and prints.
Same with URB?
return;- default:
dev_dbg(dev, "irq urb failure with status: %d\n", urb->status);break;So it's failed, but you're going to attempt to submit it anyway?
Yes, I don't know the reason why it failed, it might succeed the next time. But this is also something that someone with real life experience with USB failures could weigh in on. Maybe I should send a reset request so the device can reset its state machine, I don't know.
USB connections are usually pretty reliable. Sometimes there are transient errors, but they are relatively rare. No one would criticize a driver for giving up the first time it gets an error (especially if there was an easy way to reset it) -- but people will get annoyed if a ton of error messages shows up on the console whenever they unplug the device.
In general, the overall design of the driver seems to be reasonable. I can't judge the interfaces with other subsystems or the other aspects of their design, but the USB part is okay. (I haven't gone through it in detail.)
Alan Stern