![Hindin Joseph](/assets/img/avatar_default.png)
It looks like I've run into some inconsistency in the USB stack behavior. The USB stack maintains, among others, two states for the attach USB device: authorized and owned. Authorization state is accessible to the user space code through correspondent sysfs files, the ownership can be set by claiming the hub's port with ioctl call. Both state may be set before the device is attached, by access the hub settings. When the new device is attached, both authorization and ownership prevent the kernel USB stack from setting the newly attached device configuration, but when the device is authorized, the ownership state is ignored. It looks like ignoring the ownership state on authorization make the stack behavior inconsistent; it also prevents the user space code from completely overriding configuration selection, important for implementing workarounds for bugs in the device configuration selection. The following patch makes the stack behavior more consistent, by moving ownership test into usb_choose_configuration - the later function is used both by generic_probe and usb_authorize_device Signed-off-by: Joseph Hindin <hindin@gmail.com> Acked-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
247 lines
6.9 KiB
C
247 lines
6.9 KiB
C
/*
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* drivers/usb/generic.c - generic driver for USB devices (not interfaces)
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*
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* (C) Copyright 2005 Greg Kroah-Hartman <gregkh@suse.de>
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*
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* based on drivers/usb/usb.c which had the following copyrights:
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* (C) Copyright Linus Torvalds 1999
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* (C) Copyright Johannes Erdfelt 1999-2001
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* (C) Copyright Andreas Gal 1999
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* (C) Copyright Gregory P. Smith 1999
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* (C) Copyright Deti Fliegl 1999 (new USB architecture)
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* (C) Copyright Randy Dunlap 2000
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* (C) Copyright David Brownell 2000-2004
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* (C) Copyright Yggdrasil Computing, Inc. 2000
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* (usb_device_id matching changes by Adam J. Richter)
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* (C) Copyright Greg Kroah-Hartman 2002-2003
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*
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*/
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#include <linux/usb.h>
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#include <linux/usb/hcd.h>
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#include "usb.h"
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static inline const char *plural(int n)
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{
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return (n == 1 ? "" : "s");
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}
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static int is_rndis(struct usb_interface_descriptor *desc)
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{
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return desc->bInterfaceClass == USB_CLASS_COMM
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&& desc->bInterfaceSubClass == 2
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&& desc->bInterfaceProtocol == 0xff;
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}
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static int is_activesync(struct usb_interface_descriptor *desc)
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{
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return desc->bInterfaceClass == USB_CLASS_MISC
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&& desc->bInterfaceSubClass == 1
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&& desc->bInterfaceProtocol == 1;
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}
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int usb_choose_configuration(struct usb_device *udev)
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{
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int i;
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int num_configs;
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int insufficient_power = 0;
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struct usb_host_config *c, *best;
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if (usb_device_is_owned(udev))
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return 0;
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best = NULL;
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c = udev->config;
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num_configs = udev->descriptor.bNumConfigurations;
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for (i = 0; i < num_configs; (i++, c++)) {
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struct usb_interface_descriptor *desc = NULL;
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/* It's possible that a config has no interfaces! */
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if (c->desc.bNumInterfaces > 0)
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desc = &c->intf_cache[0]->altsetting->desc;
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/*
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* HP's USB bus-powered keyboard has only one configuration
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* and it claims to be self-powered; other devices may have
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* similar errors in their descriptors. If the next test
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* were allowed to execute, such configurations would always
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* be rejected and the devices would not work as expected.
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* In the meantime, we run the risk of selecting a config
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* that requires external power at a time when that power
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* isn't available. It seems to be the lesser of two evils.
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*
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* Bugzilla #6448 reports a device that appears to crash
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* when it receives a GET_DEVICE_STATUS request! We don't
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* have any other way to tell whether a device is self-powered,
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* but since we don't use that information anywhere but here,
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* the call has been removed.
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*
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* Maybe the GET_DEVICE_STATUS call and the test below can
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* be reinstated when device firmwares become more reliable.
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* Don't hold your breath.
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*/
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#if 0
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/* Rule out self-powered configs for a bus-powered device */
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if (bus_powered && (c->desc.bmAttributes &
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USB_CONFIG_ATT_SELFPOWER))
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continue;
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#endif
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/*
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* The next test may not be as effective as it should be.
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* Some hubs have errors in their descriptor, claiming
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* to be self-powered when they are really bus-powered.
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* We will overestimate the amount of current such hubs
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* make available for each port.
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*
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* This is a fairly benign sort of failure. It won't
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* cause us to reject configurations that we should have
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* accepted.
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*/
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/* Rule out configs that draw too much bus current */
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if (c->desc.bMaxPower * 2 > udev->bus_mA) {
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insufficient_power++;
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continue;
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}
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/* When the first config's first interface is one of Microsoft's
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* pet nonstandard Ethernet-over-USB protocols, ignore it unless
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* this kernel has enabled the necessary host side driver.
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* But: Don't ignore it if it's the only config.
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*/
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if (i == 0 && num_configs > 1 && desc &&
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(is_rndis(desc) || is_activesync(desc))) {
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#if !defined(CONFIG_USB_NET_RNDIS_HOST) && !defined(CONFIG_USB_NET_RNDIS_HOST_MODULE)
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continue;
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#else
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best = c;
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#endif
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}
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/* From the remaining configs, choose the first one whose
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* first interface is for a non-vendor-specific class.
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* Reason: Linux is more likely to have a class driver
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* than a vendor-specific driver. */
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else if (udev->descriptor.bDeviceClass !=
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USB_CLASS_VENDOR_SPEC &&
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(desc && desc->bInterfaceClass !=
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USB_CLASS_VENDOR_SPEC)) {
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best = c;
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break;
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}
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/* If all the remaining configs are vendor-specific,
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* choose the first one. */
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else if (!best)
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best = c;
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}
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if (insufficient_power > 0)
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dev_info(&udev->dev, "rejected %d configuration%s "
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"due to insufficient available bus power\n",
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insufficient_power, plural(insufficient_power));
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if (best) {
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i = best->desc.bConfigurationValue;
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dev_dbg(&udev->dev,
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"configuration #%d chosen from %d choice%s\n",
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i, num_configs, plural(num_configs));
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} else {
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i = -1;
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dev_warn(&udev->dev,
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"no configuration chosen from %d choice%s\n",
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num_configs, plural(num_configs));
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}
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return i;
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}
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static int generic_probe(struct usb_device *udev)
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{
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int err, c;
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/* Choose and set the configuration. This registers the interfaces
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* with the driver core and lets interface drivers bind to them.
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*/
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if (udev->authorized == 0)
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dev_err(&udev->dev, "Device is not authorized for usage\n");
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else {
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c = usb_choose_configuration(udev);
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if (c >= 0) {
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err = usb_set_configuration(udev, c);
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if (err) {
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dev_err(&udev->dev, "can't set config #%d, error %d\n",
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c, err);
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/* This need not be fatal. The user can try to
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* set other configurations. */
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}
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}
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}
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/* USB device state == configured ... usable */
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usb_notify_add_device(udev);
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return 0;
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}
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static void generic_disconnect(struct usb_device *udev)
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{
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usb_notify_remove_device(udev);
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/* if this is only an unbind, not a physical disconnect, then
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* unconfigure the device */
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if (udev->actconfig)
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usb_set_configuration(udev, -1);
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}
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#ifdef CONFIG_PM
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static int generic_suspend(struct usb_device *udev, pm_message_t msg)
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{
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int rc;
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/* Normal USB devices suspend through their upstream port.
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* Root hubs don't have upstream ports to suspend,
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* so we have to shut down their downstream HC-to-USB
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* interfaces manually by doing a bus (or "global") suspend.
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*/
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if (!udev->parent)
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rc = hcd_bus_suspend(udev, msg);
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/* Non-root devices don't need to do anything for FREEZE or PRETHAW */
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else if (msg.event == PM_EVENT_FREEZE || msg.event == PM_EVENT_PRETHAW)
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rc = 0;
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else
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rc = usb_port_suspend(udev, msg);
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return rc;
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}
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static int generic_resume(struct usb_device *udev, pm_message_t msg)
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{
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int rc;
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/* Normal USB devices resume/reset through their upstream port.
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* Root hubs don't have upstream ports to resume or reset,
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* so we have to start up their downstream HC-to-USB
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* interfaces manually by doing a bus (or "global") resume.
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*/
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if (!udev->parent)
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rc = hcd_bus_resume(udev, msg);
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else
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rc = usb_port_resume(udev, msg);
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return rc;
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}
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#endif /* CONFIG_PM */
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struct usb_device_driver usb_generic_driver = {
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.name = "usb",
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.probe = generic_probe,
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.disconnect = generic_disconnect,
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#ifdef CONFIG_PM
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.suspend = generic_suspend,
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.resume = generic_resume,
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#endif
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.supports_autosuspend = 1,
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};
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