Hello. After upgrading my kernel to 3.14.4 I discovered that my Intel NUC could no longer utilize two PCTV nanoStick T2 290e USB DVB adapters at the same time. I've tried further upgrading the kernel to 3.15-rc7 (or to usb-next) which exhibit the same behavior. Using only one nanoStick works fine. So after some git bisecting I've found the offending commit to be 1386ff75797a187df324062fb4e929152392da88 Revert "xhci: Set scatter-gather limit to avoid failed block writes." I've verified that reverting only the offending commit from 3.15-rc7 will make the DVB adapters work right again. Below are verbose usb dmesg logs of me plugging the adapters in and trying to tune to DVB channels both with vanilla 3.15-rc7 and with the commit reverted: Vanilla 3.15-rc7: http://ase.pp.fi/usb-debug/dmesg-linux-3.15-rc7-bad.log 3.15-rc7 with revert: http://ase.pp.fi/usb-debug/dmesg-linux-3.15-rc7-good.log Apparently things start to go wrong because host gets halted: [ 88.264911] xhci_hcd 0000:00:14.0: xHCI host not responding to stop endpoint command. [ 88.264917] xhci_hcd 0000:00:14.0: Assuming host is dying, halting host. Apparently the people using OpenELEC have ran into similar issues: https://github.com/OpenELEC/OpenELEC.tv/pull/3165 Any ideas how to proceed? It seems the commit cannot be simply reverted as that will break something else. Below is also my lsusb -v: Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub Device Descriptor: bLength 18 bDescriptorType 1 bcdUSB 3.00 bDeviceClass 9 Hub bDeviceSubClass 0 Unused bDeviceProtocol 3 bMaxPacketSize0 9 idVendor 0x1d6b Linux Foundation idProduct 0x0003 3.0 root hub bcdDevice 3.15 iManufacturer 3 Linux 3.15.0-rc7-00001-ge545e63 xhci_hcd iProduct 2 xHCI Host Controller iSerial 1 0000:00:14.0 bNumConfigurations 1 Configuration Descriptor: bLength 9 bDescriptorType 2 wTotalLength 31 bNumInterfaces 1 bConfigurationValue 1 iConfiguration 0 bmAttributes 0xe0 Self Powered Remote Wakeup MaxPower 0mA Interface Descriptor: bLength 9 bDescriptorType 4 bInterfaceNumber 0 bAlternateSetting 0 bNumEndpoints 1 bInterfaceClass 9 Hub bInterfaceSubClass 0 Unused bInterfaceProtocol 0 Full speed (or root) hub iInterface 0 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x81 EP 1 IN bmAttributes 3 Transfer Type Interrupt Synch Type None Usage Type Data wMaxPacketSize 0x0004 1x 4 bytes bInterval 12 bMaxBurst 0 Hub Descriptor: bLength 12 bDescriptorType 42 nNbrPorts 4 wHubCharacteristic 0x000a No power switching (usb 1.0) Per-port overcurrent protection bPwrOn2PwrGood 10 * 2 milli seconds bHubContrCurrent 0 milli Ampere bHubDecLat 0.0 micro seconds wHubDelay 0 nano seconds DeviceRemovable 0x00 Hub Port Status: Port 1: 0000.02a0 5Gbps power Rx.Detect Port 2: 0000.02a0 5Gbps power Rx.Detect Port 3: 0000.02a0 5Gbps power Rx.Detect Port 4: 0000.02a0 5Gbps power Rx.Detect Binary Object Store Descriptor: bLength 5 bDescriptorType 15 wTotalLength 15 bNumDeviceCaps 1 SuperSpeed USB Device Capability: bLength 10 bDescriptorType 16 bDevCapabilityType 3 bmAttributes 0x02 Latency Tolerance Messages (LTM) Supported wSpeedsSupported 0x0008 Device can operate at SuperSpeed (5Gbps) bFunctionalitySupport 3 Lowest fully-functional device speed is SuperSpeed (5Gbps) bU1DevExitLat 10 micro seconds bU2DevExitLat 512 micro seconds Device Status: 0x0001 Self Powered Bus 003 Device 002: ID 8087:8000 Intel Corp. Device Descriptor: bLength 18 bDescriptorType 1 bcdUSB 2.00 bDeviceClass 9 Hub bDeviceSubClass 0 Unused bDeviceProtocol 1 Single TT bMaxPacketSize0 64 idVendor 0x8087 Intel Corp. idProduct 0x8000 bcdDevice 0.04 iManufacturer 0 iProduct 0 iSerial 0 bNumConfigurations 1 Configuration Descriptor: bLength 9 bDescriptorType 2 wTotalLength 25 bNumInterfaces 1 bConfigurationValue 1 iConfiguration 0 bmAttributes 0xe0 Self Powered Remote Wakeup MaxPower 0mA Interface Descriptor: bLength 9 bDescriptorType 4 bInterfaceNumber 0 bAlternateSetting 0 bNumEndpoints 1 bInterfaceClass 9 Hub bInterfaceSubClass 0 Unused bInterfaceProtocol 0 Full speed (or root) hub iInterface 0 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x81 EP 1 IN bmAttributes 3 Transfer Type Interrupt Synch Type None Usage Type Data wMaxPacketSize 0x0002 1x 2 bytes bInterval 12 Hub Descriptor: bLength 11 bDescriptorType 41 nNbrPorts 8 wHubCharacteristic 0x0009 Per-port power switching Per-port overcurrent protection TT think time 8 FS bits bPwrOn2PwrGood 0 * 2 milli seconds bHubContrCurrent 0 milli Ampere DeviceRemovable 0x00 0x00 PortPwrCtrlMask 0xff 0xff Hub Port Status: Port 1: 0000.0100 power Port 2: 0000.0100 power Port 3: 0000.0100 power Port 4: 0000.0100 power Port 5: 0000.0100 power Port 6: 0000.0100 power Port 7: 0000.0100 power Port 8: 0000.0100 power Device Qualifier (for other device speed): bLength 10 bDescriptorType 6 bcdUSB 2.00 bDeviceClass 9 Hub bDeviceSubClass 0 Unused bDeviceProtocol 0 Full speed (or root) hub bMaxPacketSize0 64 bNumConfigurations 1 Device Status: 0x0001 Self Powered Bus 003 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Device Descriptor: bLength 18 bDescriptorType 1 bcdUSB 2.00 bDeviceClass 9 Hub bDeviceSubClass 0 Unused bDeviceProtocol 0 Full speed (or root) hub bMaxPacketSize0 64 idVendor 0x1d6b Linux Foundation idProduct 0x0002 2.0 root hub bcdDevice 3.15 iManufacturer 3 Linux 3.15.0-rc7-00001-ge545e63 ehci_hcd iProduct 2 EHCI Host Controller iSerial 1 0000:00:1d.0 bNumConfigurations 1 Configuration Descriptor: bLength 9 bDescriptorType 2 wTotalLength 25 bNumInterfaces 1 bConfigurationValue 1 iConfiguration 0 bmAttributes 0xe0 Self Powered Remote Wakeup MaxPower 0mA Interface Descriptor: bLength 9 bDescriptorType 4 bInterfaceNumber 0 bAlternateSetting 0 bNumEndpoints 1 bInterfaceClass 9 Hub bInterfaceSubClass 0 Unused bInterfaceProtocol 0 Full speed (or root) hub iInterface 0 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x81 EP 1 IN bmAttributes 3 Transfer Type Interrupt Synch Type None Usage Type Data wMaxPacketSize 0x0004 1x 4 bytes bInterval 12 Hub Descriptor: bLength 11 bDescriptorType 41 nNbrPorts 8 wHubCharacteristic 0x000a No power switching (usb 1.0) Per-port overcurrent protection bPwrOn2PwrGood 10 * 2 milli seconds bHubContrCurrent 0 milli Ampere DeviceRemovable 0x02 0x00 PortPwrCtrlMask 0xff 0xff Hub Port Status: Port 1: 0000.0507 highspeed power suspend enable connect Port 2: 0000.0100 power Port 3: 0000.0100 power Port 4: 0000.0100 power Port 5: 0000.0100 power Port 6: 0000.0100 power Port 7: 0000.0100 power Port 8: 0000.0100 power Device Status: 0x0001 Self Powered Bus 001 Device 003: ID 2013:024f PCTV Systems nanoStick T2 290e Device Descriptor: bLength 18 bDescriptorType 1 bcdUSB 2.00 bDeviceClass 0 (Defined at Interface level) bDeviceSubClass 0 bDeviceProtocol 0 bMaxPacketSize0 64 idVendor 0x2013 PCTV Systems idProduct 0x024f nanoStick T2 290e bcdDevice 1.00 iManufacturer 1 PCTV Systems iProduct 2 PCTV 290e iSerial 3 00000010YZ4N bNumConfigurations 1 Configuration Descriptor: bLength 9 bDescriptorType 2 wTotalLength 55 bNumInterfaces 1 bConfigurationValue 1 iConfiguration 0 bmAttributes 0x80 (Bus Powered) MaxPower 500mA Interface Descriptor: bLength 9 bDescriptorType 4 bInterfaceNumber 0 bAlternateSetting 0 bNumEndpoints 2 bInterfaceClass 255 Vendor Specific Class bInterfaceSubClass 0 bInterfaceProtocol 0 iInterface 0 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x84 EP 4 IN bmAttributes 1 Transfer Type Isochronous Synch Type None Usage Type Data wMaxPacketSize 0x0000 1x 0 bytes bInterval 1 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x85 EP 5 IN bmAttributes 1 Transfer Type Isochronous Synch Type None Usage Type Data wMaxPacketSize 0x0000 1x 0 bytes bInterval 1 Interface Descriptor: bLength 9 bDescriptorType 4 bInterfaceNumber 0 bAlternateSetting 1 bNumEndpoints 2 bInterfaceClass 255 Vendor Specific Class bInterfaceSubClass 0 bInterfaceProtocol 0 iInterface 0 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x84 EP 4 IN bmAttributes 1 Transfer Type Isochronous Synch Type None Usage Type Data wMaxPacketSize 0x03ac 1x 940 bytes bInterval 1 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x85 EP 5 IN bmAttributes 1 Transfer Type Isochronous Synch Type None Usage Type Data wMaxPacketSize 0x03ac 1x 940 bytes bInterval 1 Device Qualifier (for other device speed): bLength 10 bDescriptorType 6 bcdUSB 2.00 bDeviceClass 0 (Defined at Interface level) bDeviceSubClass 0 bDeviceProtocol 0 bMaxPacketSize0 64 bNumConfigurations 1 Device Status: 0x0000 (Bus Powered) Bus 001 Device 002: ID 2013:024f PCTV Systems nanoStick T2 290e Device Descriptor: bLength 18 bDescriptorType 1 bcdUSB 2.00 bDeviceClass 0 (Defined at Interface level) bDeviceSubClass 0 bDeviceProtocol 0 bMaxPacketSize0 64 idVendor 0x2013 PCTV Systems idProduct 0x024f nanoStick T2 290e bcdDevice 1.00 iManufacturer 1 PCTV Systems iProduct 2 PCTV 290e iSerial 3 00000010V0PQ bNumConfigurations 1 Configuration Descriptor: bLength 9 bDescriptorType 2 wTotalLength 55 bNumInterfaces 1 bConfigurationValue 1 iConfiguration 0 bmAttributes 0x80 (Bus Powered) MaxPower 500mA Interface Descriptor: bLength 9 bDescriptorType 4 bInterfaceNumber 0 bAlternateSetting 0 bNumEndpoints 2 bInterfaceClass 255 Vendor Specific Class bInterfaceSubClass 0 bInterfaceProtocol 0 iInterface 0 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x84 EP 4 IN bmAttributes 1 Transfer Type Isochronous Synch Type None Usage Type Data wMaxPacketSize 0x0000 1x 0 bytes bInterval 1 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x85 EP 5 IN bmAttributes 1 Transfer Type Isochronous Synch Type None Usage Type Data wMaxPacketSize 0x0000 1x 0 bytes bInterval 1 Interface Descriptor: bLength 9 bDescriptorType 4 bInterfaceNumber 0 bAlternateSetting 1 bNumEndpoints 2 bInterfaceClass 255 Vendor Specific Class bInterfaceSubClass 0 bInterfaceProtocol 0 iInterface 0 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x84 EP 4 IN bmAttributes 1 Transfer Type Isochronous Synch Type None Usage Type Data wMaxPacketSize 0x03ac 1x 940 bytes bInterval 1 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x85 EP 5 IN bmAttributes 1 Transfer Type Isochronous Synch Type None Usage Type Data wMaxPacketSize 0x03ac 1x 940 bytes bInterval 1 Device Qualifier (for other device speed): bLength 10 bDescriptorType 6 bcdUSB 2.00 bDeviceClass 0 (Defined at Interface level) bDeviceSubClass 0 bDeviceProtocol 0 bMaxPacketSize0 64 bNumConfigurations 1 Device Status: 0x0000 (Bus Powered) Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Device Descriptor: bLength 18 bDescriptorType 1 bcdUSB 2.00 bDeviceClass 9 Hub bDeviceSubClass 0 Unused bDeviceProtocol 1 Single TT bMaxPacketSize0 64 idVendor 0x1d6b Linux Foundation idProduct 0x0002 2.0 root hub bcdDevice 3.15 iManufacturer 3 Linux 3.15.0-rc7-00001-ge545e63 xhci_hcd iProduct 2 xHCI Host Controller iSerial 1 0000:00:14.0 bNumConfigurations 1 Configuration Descriptor: bLength 9 bDescriptorType 2 wTotalLength 25 bNumInterfaces 1 bConfigurationValue 1 iConfiguration 0 bmAttributes 0xe0 Self Powered Remote Wakeup MaxPower 0mA Interface Descriptor: bLength 9 bDescriptorType 4 bInterfaceNumber 0 bAlternateSetting 0 bNumEndpoints 1 bInterfaceClass 9 Hub bInterfaceSubClass 0 Unused bInterfaceProtocol 0 Full speed (or root) hub iInterface 0 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x81 EP 1 IN bmAttributes 3 Transfer Type Interrupt Synch Type None Usage Type Data wMaxPacketSize 0x0004 1x 4 bytes bInterval 12 Hub Descriptor: bLength 11 bDescriptorType 41 nNbrPorts 9 wHubCharacteristic 0x000a No power switching (usb 1.0) Per-port overcurrent protection TT think time 8 FS bits bPwrOn2PwrGood 10 * 2 milli seconds bHubContrCurrent 0 milli Ampere DeviceRemovable 0x00 0x02 PortPwrCtrlMask 0xff 0xff Hub Port Status: Port 1: 0000.0503 highspeed power enable connect Port 2: 0000.0503 highspeed power enable connect Port 3: 0000.0100 power Port 4: 0000.0100 power Port 5: 0000.0100 power Port 6: 0000.0100 power Port 7: 0000.0100 power Port 8: 0000.0100 power Port 9: 0000.0100 power Device Status: 0x0001 Self Powered Best regards, -- Antti Seppälä -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx 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