> -----Original Message----- > From: Sarah Sharp [mailto:sarah.a.sharp@xxxxxxxxxxxxxxx] > Sent: Tuesday, August 17, 2010 2:39 PM > To: John Youn > Cc: linux-usb@xxxxxxxxxxxxxxx; Alan Stern; Daniel Drake; libusb- > devel@xxxxxxxxxxxxxxxxxxxxx; Greg KH > Subject: Re: [RFC] USB 3.0 Hub Changes > > Hi John, > > I've been testing your patch with a VIA USB 3.0 hub prototype. > > I've tested with a mouse, USB 3.0 hard drive, and high speed webcam. > All devices seem to work fine under the hub with your patch. The only > slightly concerning thing is that I see a bunch of stalls when I try to > run `lsusb -v` for the USB 3.0 hub portion. The lsusb output says: > > can't get hub descriptor: Broken pipe > Device Status: 0x0001 > Self Powered > > The USB 3.0 hub descriptor is a different descriptor code (and format) > than USB 1.1 or 2.0 hubs. It looks like your patch changed the kernel > code in get_hub_descriptor() to ask for the right descriptor, but I'm > not sure if userspace is issuing a control transfer through usbfs and > bypassing the kernel. > > Full USBmon, lsusb and dmesg output attached. I'm running lsusb > (usbutils) version 0.82. > > The first failed transfer is > ffff88012c161cc0 3629591912 S Ci:9:002:0 s a0 06 2900 0000 000d 13 < > ffff88012c161cc0 3629595966 C Ci:9:002:0 -32 0 > > bmRequestType = a0, bRequest = 06, wValue = 2900, wIndex = 0000, > wLength > = 000d > > That looks like a USB 2.0 GetHubDescriptor request to me. > > Alan, Daniel, or Greg, do you know if lsusb is calling through libusb > to > get the hub descriptor, or is it just getting cached descriptors from > the kernel? > > > John, I'm concerned that you're blindly assigning the USB 3.0 hub > descriptor to a usb_hub_descriptor. The current structure is: > > struct usb_hub_descriptor { > __u8 bDescLength; > __u8 bDescriptorType; > __u8 bNbrPorts; > __le16 wHubCharacteristics; > __u8 bPwrOn2PwrGood; > __u8 bHubContrCurrent; > /* add 1 bit for hub status change; round to bytes */ > __u8 DeviceRemovable[(USB_MAXCHILDREN + 1 + 7) / 8]; > __u8 PortPwrCtrlMask[(USB_MAXCHILDREN + 1 + 7) / 8]; > } __attribute__ ((packed)); > > The USB 3.0 hub descriptor should look something like this: > > struct usb_hub_usb3_descriptor { > __u8 bDescLength; > __u8 bDescriptorType; > __u8 bNbrPorts; > __le16 wHubCharacteristics; > __u8 bPwrOn2PwrGood; > __u8 bHubContrCurrent; > /* add 1 bit for hub status change; round to bytes */ > __u8 bHubHdrDecLat; > __u16 wHubDelay; > __u8 DeviceRemovable[2]; > } __attribute__ ((packed)); > > The descriptor is longer, and the fields after bHubContrCurrent don't > align properly. So I don't think your current approach of just > assigning the new hub descriptor to a pointer of the old hub descriptor > type is going to work very well. > Actually the 3.0 descriptor is smaller than the largest 2.0 descriptor, so it fits into the same buffer. And most of the structure is the same so I left it like that so the core can access the same structure and fields. The differences are only at the end, so for 3.0 hubs I skipped where the hub accesses the 2.0-only fields DeviceRemovable and PortPwrCtrlMask, and put the FIXME comment. For the new 3.0 fields, there is no code to use them yet. Not a complete solution obviously but I did somewhat account for the difference. John -- 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
