usb-linux: Get the active configuration from sysfs rather then asking the dev
Some devices seem to choke on receiving a USB_REQ_GET_CONFIGURATION ctrl msg
(witnessed with a digital picture frame usb id 1908:1320).
When usb_fs_type == USB_FS_SYS, the active configuration 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: Anthony Liguori <aliguori@us.ibm.com>
diff --git a/usb-linux.c b/usb-linux.c
index 111fe1c..ccf7073 100644
--- a/usb-linux.c
+++ b/usb-linux.c
@@ -152,6 +152,8 @@
static int usb_host_close(USBHostDevice *dev);
static int parse_filter(const char *spec, struct USBAutoFilter *f);
static void usb_host_auto_check(void *unused);
+static int usb_host_read_file(char *line, size_t line_size,
+ const char *device_file, const char *device_name);
static int is_isoc(USBHostDevice *s, int ep)
{
@@ -781,6 +783,23 @@
struct usb_ctrltransfer ct;
int ret;
+ if (usb_fs_type == USB_FS_SYS) {
+ char device_name[32], line[1024];
+ int configuration;
+
+ sprintf(device_name, "%d-%d", s->bus_num, s->devpath);
+
+ if (!usb_host_read_file(line, sizeof(line), "bConfigurationValue",
+ device_name)) {
+ goto usbdevfs;
+ }
+ if (sscanf(line, "%d", &configuration) != 1) {
+ goto usbdevfs;
+ }
+ return configuration;
+ }
+
+usbdevfs:
ct.bRequestType = USB_DIR_IN;
ct.bRequest = USB_REQ_GET_CONFIGURATION;
ct.wValue = 0;
