Patch is now in mainline. Pending the requisite testing carried out by Ubuntu team, may I please have this patch nominated for promotion to downstream jobs (ie: Xenial, Wily, and Vivid).
Thank you. commit 6fb650d43da3e7054984dc548eaa88765a94d49f Author: Alan Stern <st...@rowland.harvard.edu> Date: Fri Apr 29 15:25:17 2016 -0400 USB: leave LPM alone if possible when binding/unbinding interface drivers When a USB driver is bound to an interface (either through probing or by claiming it) or is unbound from an interface, the USB core always disables Link Power Management during the transition and then re-enables it afterward. The reason is because the driver might want to prevent hub-initiated link power transitions, in which case the HCD would have to recalculate the various LPM parameters. This recalculation takes place when LPM is re-enabled and the new parameters are sent to the device and its parent hub. However, if the driver does not want to prevent hub-initiated link power transitions then none of this work is necessary. The parameters don't need to be recalculated, and LPM doesn't need to be disabled and re-enabled. It turns out that disabling and enabling LPM can be time-consuming, enough so that it interferes with user programs that want to claim and release interfaces rapidly via usbfs. Since the usbfs kernel driver doesn't set the disable_hub_initiated_lpm flag, we can speed things up and get the user programs to work by leaving LPM alone whenever the flag isn't set. And while we're improving the way disable_hub_initiated_lpm gets used, let's also fix its kerneldoc. Signed-off-by: Alan Stern <st...@rowland.harvard.edu> Tested-by: Matthew Giassa <matt...@giassa.net> CC: Mathias Nyman <mathias.ny...@intel.com> CC: <sta...@vger.kernel.org> Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org> ** Patch added: "6fb650d43da3e7054984dc548eaa88765a94d49f.patch" https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1577024/+attachment/4670331/+files/6fb650d43da3e7054984dc548eaa88765a94d49f.patch -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1577024 Title: Kernel 4.2.X and 4.4.X - Fix USB3.0 link power management (LPM) claim/release logic in USBFS Status in linux package in Ubuntu: Triaged Status in linux source package in Vivid: Triaged Status in linux source package in Wily: Triaged Status in linux source package in Xenial: Triaged Bug description: I am currently carrying out kernel testing and debugging with Alan Stern on the mainline kernel. Alan has proposed a patch to resolve a bug in USBFS that causes USB machine vision cameras to fail on kernels that contain the following patch: commit e951f84074b84a3f5aecbffd01da74576e0068d5 Author: Lu Baolu <baolu...@linux.intel.com> Date: Tue Jun 16 09:08:26 2015 +0800 usb: core: lpm: set lpm_capable for root hub device commit 2d2a316765d956bc5cb6bb367b2ec52ca59ab8e9 upstream. There is an issue in this patch that impacts software that rapidly issues claim/release calls in USBFS, and all of our customers that use Ubuntu 14.04.4 (kernel 4.2.x) and Ubuntu 16.04 (kernel 4.4.x) are unable to communicate with their machine vision cameras using our software stack. The patch for the mainline kernel is being tested, and is currently posted, along with a history of this issue, at: https://bugzilla.kernel.org/show_bug.cgi?id=115961 Right now, all of our customers have to either use an older kernel, or manually patch their own kernel with the fix provided by Alan if they are required to use a newer kernel. I am raising this bug so that, once the patch is submitted to the the mainline/linus series, it can be included in the next "monthly" kernel update made available to the general public, and so our customers can just run a normal "vanilla" system without having to rely on manually patching their kernel every time they need to update. I can be contacted at: matt...@giassa.net matthew.gia...@ptgrey.com Thank you. ProblemType: Bug DistroRelease: Ubuntu 14.04 Package: linux-image-3.13.0-55-generic 3.13.0-55.94 ProcVersionSignature: Ubuntu 3.13.0-55.94-generic 3.13.11-ckt20 Uname: Linux 3.13.0-55-generic i686 NonfreeKernelModules: nvidia ApportVersion: 2.14.1-0ubuntu3.19 Architecture: i386 AudioDevicesInUse: USER PID ACCESS COMMAND /dev/snd/controlC0: owner 4035 F.... pulseaudio CurrentDesktop: Unity Date: Sat Apr 30 10:36:15 2016 EcryptfsInUse: Yes HibernationDevice: RESUME=UUID=0287e25d-68d6-4390-aced-c682b8e13b60 InstallationDate: Installed on 2013-09-23 (949 days ago) InstallationMedia: Ubuntu 12.04.3 LTS "Precise Pangolin" - Release i386 (20130820.1) IwConfig: lo no wireless extensions. cscotun0 no wireless extensions. eth0 no wireless extensions. MachineType: Hewlett-Packard HP xw4600 Workstation ProcFB: ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.13.0-55-generic root=UUID=292845c9-c333-4592-aa06-bc01f45d3ee6 ro quiet splash RelatedPackageVersions: linux-restricted-modules-3.13.0-55-generic N/A linux-backports-modules-3.13.0-55-generic N/A linux-firmware 1.127.19 RfKill: SourcePackage: linux UpgradeStatus: Upgraded to trusty on 2014-07-30 (639 days ago) dmi.bios.date: 07/09/2012 dmi.bios.vendor: Hewlett-Packard dmi.bios.version: 786F3 v01.34 dmi.board.asset.tag: CAC94101JZ dmi.board.name: 0AA0h dmi.board.vendor: Hewlett-Packard dmi.chassis.asset.tag: CAC94101JZ dmi.chassis.type: 6 dmi.chassis.vendor: Hewlett-Packard dmi.modalias: dmi:bvnHewlett-Packard:bvr786F3v01.34:bd07/09/2012:svnHewlett-Packard:pnHPxw4600Workstation:pvr:rvnHewlett-Packard:rn0AA0h:rvr:cvnHewlett-Packard:ct6:cvr: dmi.product.name: HP xw4600 Workstation dmi.sys.vendor: Hewlett-Packard To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1577024/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp