From stern@rowland.harvard.edu Fri Aug 10 11:06:57 2007 From: Alan Stern Date: Wed, 8 Aug 2007 11:59:18 -0400 (EDT) Subject: USB: don't touch sysfs stuff when altsetting is unchanged To: Greg KH Cc: USB development list Message-ID: This patch (as955) prevents the interface-related sysfs files and endpoint pseudo-devices from being deleted and recreated when a call to usb_set_interface() specifies the current altsetting. Since the altsetting doesn't get changed, there's no need to do anything. Furthermore, avoiding changes to the endpoint devices will be necessary in the future. This code is called from usb_reset_device(), which gets invoked for reset-resume processing, but upcoming changes to the PM and driver cores will make it impossible to register devices while a suspend/resume transition is in progress. Since we don't need to re-register those endpoint devices anyhow, it's best to skip the whole thing. Signed-off-by: Alan Stern Signed-off-by: Greg Kroah-Hartman --- drivers/usb/core/message.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) --- a/drivers/usb/core/message.c +++ b/drivers/usb/core/message.c @@ -1173,6 +1173,7 @@ int usb_set_interface(struct usb_device struct usb_host_interface *alt; int ret; int manual = 0; + int changed; if (dev->state == USB_STATE_SUSPENDED) return -EHOSTUNREACH; @@ -1212,7 +1213,8 @@ int usb_set_interface(struct usb_device */ /* prevent submissions using previous endpoint settings */ - if (device_is_registered(&iface->dev)) + changed = (iface->cur_altsetting != alt); + if (changed && device_is_registered(&iface->dev)) usb_remove_sysfs_intf_files(iface); usb_disable_interface(dev, iface); @@ -1249,7 +1251,7 @@ int usb_set_interface(struct usb_device * (Likewise, EP0 never "halts" on well designed devices.) */ usb_enable_interface(dev, iface); - if (device_is_registered(&iface->dev)) + if (changed && device_is_registered(&iface->dev)) usb_create_sysfs_intf_files(iface); return 0;