On Fri, 12 Jun 2015 09:42:04 +0800 Li Jun <b47624@xxxxxxxxxxxxx> wrote: > On Thu, Jun 11, 2015 at 05:55:57PM +0300, Roger Quadros wrote: > > > > drivers/usb/core/hub.c > > > > > > > > static int usb_enumerate_device_otg(struct usb_device *udev) > > > > { > > > > int err = 0; > > > > > > > > #ifdef CONFIG_USB_OTG > > > > /* > > > > * OTG-aware devices on OTG-capable root hubs may be able to use SRP, > > > > * to wake us after we've powered off VBUS; and HNP, switching roles > > > > * "host" to "peripheral". The OTG descriptor helps figure this out. > > > > */ > > > > if (!udev->bus->is_b_host > > > > && udev->config > > > > && udev->parent == udev->bus->root_hub) { > > > > struct usb_otg_descriptor *desc = NULL; > > > > struct usb_bus *bus = udev->bus; > > > > > > > > /* descriptor may appear anywhere in config */ > > > > if (__usb_get_extra_descriptor (udev->rawdescriptors[0], > > > > le16_to_cpu(udev->config[0].desc.wTotalLength), > > > > USB_DT_OTG, (void **) &desc) == 0) { > > > > if (desc->bmAttributes & USB_OTG_HNP) { > > > > unsigned port1 = udev->portnum; > > > > > > > > dev_info(&udev->dev, > > > > "Dual-Role OTG device on %sHNP port\n", > > > > (port1 == bus->otg_port) > > > > ? "" : "non-"); > > > > > > > > /* enable HNP before suspend, it's simpler */ > > > > if (port1 == bus->otg_port) > > > > bus->b_hnp_enable = 1; > > > > err = usb_control_msg(udev, > > > > usb_sndctrlpipe(udev, 0), > > > > USB_REQ_SET_FEATURE, 0, > > > > bus->b_hnp_enable > > > > ? USB_DEVICE_B_HNP_ENABLE > > > > : USB_DEVICE_A_ALT_HNP_SUPPORT, > > > > 0, NULL, 0, USB_CTRL_SET_TIMEOUT); > > > > > > > > We're sending out this control request even if this host port is not OTG. > > > > Isn't that wrong? > > > > > > So send USB_DEVICE_A_ALT_HNP_SUPPORT request. > > > This is correct in OTG 1.x, its intention is to remind the user who is > > > connecting the HNP capable OTG device to a non-OTG port, He can change > > > to another port of this machine which is a OTG port(with HNP). > > > > I didn't understand. > > If CONFIG_USB_OTG is enabled doesn't mean that this USB host port is OTG host. > Yes, only CONFIG_USB_OTG enabled doesn't mean that this USB host port > is a OTG port, there are might multiple usb host ports, but only one > is a OTG port. Not necessarily. Many systems don't have any OTG port so that request cannot be sent even if CONFIG_USB_OTG is enabled. > > So it should not send any OTG specific request to device. Right? > Non-otg port(in OTG 1.x protocol) + OTG 1.x device, should send, > otherwise, should not send. What did you mean by Non-OTG port (in OTG 1.x protocol)? If it is Non-OTG port it doesn't understand any OTG protocol. So Non-OTG port should not send any OTG request. > > So the code you pasted here was right only for OTG 1.x, I assume > OTG 2.0 has not been released when it was designed. But now it's > out of date, it's wrong if you connect a OTG 2.0 device. > The code is wrong for non-OTG ports when CONFIG_USB_OTG is set. Peter/Felipe, any comments on this? cheers, -roger > > > > > > > > > > > > > if (err < 0) { > > > > /* OTG MESSAGE: report errors here, > > > > * customize to match your product. > > > > */ > > > > dev_info(&udev->dev, > > > > "can't set HNP mode: %d\n", > > > > err); > > > > bus->b_hnp_enable = 0; > > > > } > > > > > > > > Instead it should be moved inside the if (port1 == bus->otg_port) condition. > > > > > > Nope, as I explained above, this is really too detailed OTG protocol:) > > > > > > > > } > > > > } > > > > } > > > > #endif > > > > return err; > > > > } > > > > -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html