From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:53104) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Z34ii-0001Sr-9K for qemu-devel@nongnu.org; Thu, 11 Jun 2015 11:48:45 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Z34ie-0006B3-86 for qemu-devel@nongnu.org; Thu, 11 Jun 2015 11:48:44 -0400 Received: from smtp2.provo.novell.com ([137.65.250.81]:52453) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Z34ie-0006Al-3y for qemu-devel@nongnu.org; Thu, 11 Jun 2015 11:48:40 -0400 Message-ID: <5579AD97.1080906@suse.com> Date: Thu, 11 Jun 2015 23:47:35 +0800 From: Lin Ma MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Subject: [Qemu-devel] About usb passthru and speed mismatch Reply-To: lma@suse.com List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: kraxel@redhat.com Cc: qemu-devel@nongnu.org Hi Gerd, Based on the current implementation of 'usb_host_open' in hw/usb/host-libusb.c, When user performs usb_add, The usb device will be detached from kernel first, Then be checked for speed mismatch second. If it found speed mismatch, The usb device isn't attached to guest, But the usb device can't be reattached to kernel either. I'd like to write patch to add 'usb_check_attach' before detaching the device from kernel _or_ add 'usb_host_attach_kernel' under 'fail:' of usb_host_open, (the latter doesn't make sense I think). May I have your thoughts? BTW, Have you missed a patch: "usb: Use usb_bus_find(-1) instead of usb_enabled() in usb_device_add/usb_device_del" which sending on June 4th ? May I have your thoughts about that patch as well? Thanks, Lin