From 51099364dfa3507079b55e88af41df37914d9a89 Mon Sep 17 00:00:00 2001 From: Gerd Hoffmann Date: Thu, 23 Jun 2011 12:41:32 -0300 Subject: [RHEL6 qemu-kvm PATCH 057/115] usb-linux: Get the alt. setting from sysfs rather then asking the dev RH-Author: Gerd Hoffmann Message-id: <1308832951-8995-57-git-send-email-kraxel@redhat.com> Patchwork-id: 28380 O-Subject: [RHEL-6.2 kvm PATCH 056/115] usb-linux: Get the alt. setting from sysfs rather then asking the dev Bugzilla: 561414 632299 645351 711354 RH-Acked-by: Hans de Goede RH-Acked-by: Jes Sorensen RH-Acked-by: Kevin Wolf From: Hans de Goede At least one device I have lies when receiving a USB_REQ_GET_INTERFACE, always returning 0 even if the alternate setting is different. This is likely caused because in practice this control message is never used as the operating system's usb stack knows which alternate setting it has told the device to get into, and thus this ctrl message does not get tested by device manufacturers. When usb_fs_type == USB_FS_SYS, the active alt. setting can be read directly from sysfs, which allows using this device through qemu's usb redirection. More in general it seems a good idea to not send needless control msg's to devices, esp. as the code in question is called every time a set_interface is done. Which happens multiple times during virtual machine startup, and when device drivers are activating the usb device. Signed-off-by: Hans de Goede (cherry picked from commit c43831fb47e4ee51967870c7b5deb08789b0874c) Signed-off-by: Gerd Hoffmann --- usb-linux.c | 18 ++++++++++++++++++ 1 files changed, 18 insertions(+), 0 deletions(-) Signed-off-by: Eduardo Habkost --- usb-linux.c | 18 ++++++++++++++++++ 1 files changed, 18 insertions(+), 0 deletions(-) diff --git a/usb-linux.c b/usb-linux.c index ae7bccc..174727d 100644 --- a/usb-linux.c +++ b/usb-linux.c @@ -811,6 +811,24 @@ static uint8_t usb_linux_get_alt_setting(USBHostDevice *s, struct usb_ctrltransfer ct; int ret; + if (usb_fs_type == USB_FS_SYS) { + char device_name[64], line[1024]; + int alt_setting; + + sprintf(device_name, "%d-%d:%d.%d", s->bus_num, s->devpath, + (int)configuration, (int)interface); + + if (!usb_host_read_file(line, sizeof(line), "bAlternateSetting", + device_name)) { + goto usbdevfs; + } + if (sscanf(line, "%d", &alt_setting) != 1) { + goto usbdevfs; + } + return alt_setting; + } + +usbdevfs: ct.bRequestType = USB_DIR_IN | USB_RECIP_INTERFACE; ct.bRequest = USB_REQ_GET_INTERFACE; ct.wValue = 0; -- 1.7.3.2