USB: Check bandwidth when switching alt settings.

Make the USB core check the bandwidth when switching from one
interface alternate setting to another.  Also check the bandwidth
when resetting a configuration (so that alt setting 0 is used).  If
this check fails, the device's state is unchanged.  If the device
refuses the new alt setting, re-instate the old alt setting in the
host controller hardware.

If a USB device doesn't have an alternate interface setting 0, install
the first alt setting in its descriptors when a new configuration is
requested, or the device is reset.

Add a mutex per root hub to protect bandwidth operations:
adding/reseting/changing configurations, and changing alternate interface
settings.  We want to ensure that the xHCI host controller and the USB
device are set up for the same configurations and alternate settings.
There are two (possibly three) steps to do this:

 1. The host controller needs to check that bandwidth is available for a
    different setting, by issuing and waiting for a configure endpoint
    command.
 2. Once that returns successfully, a control message is sent to the
    device.
 3. If that fails, the host controller must be notified through another
    configure endpoint command.

The mutex is used to make these three operations seem atomic, to prevent
another driver from using more bandwidth for a different device while
we're in the middle of these operations.

While we're touching the bandwidth code, rename usb_hcd_check_bandwidth()
to usb_hcd_alloc_bandwidth().  This function does more than just check
that the bandwidth change won't exceed the bus bandwidth; it actually
changes the bandwidth configuration in the xHCI host controller.

Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 26 insertions, 1 deletions

diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index b38fd6730e2..e4b0e28f745 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -3599,6 +3599,7 @@ static int usb_reset_and_verify_device(struct usb_device *udev)
 {
 	struct usb_device		*parent_hdev = udev->parent;
 	struct usb_hub			*parent_hub;
+	struct usb_hcd			*hcd = bus_to_hcd(udev->bus);
 	struct usb_device_descriptor	descriptor = udev->descriptor;
 	int 				i, ret = 0;
 	int				port1 = udev->portnum;
@@ -3642,6 +3643,16 @@ static int usb_reset_and_verify_device(struct usb_device *udev)
 	/* Restore the device's previous configuration */
 	if (!udev->actconfig)
 		goto done;
+
+	mutex_lock(&hcd->bandwidth_mutex);
+	ret = usb_hcd_alloc_bandwidth(udev, udev->actconfig, NULL, NULL);
+	if (ret < 0) {
+		dev_warn(&udev->dev,
+				"Busted HC?  Not enough HCD resources for "
+				"old configuration.\n");
+		mutex_unlock(&hcd->bandwidth_mutex);
+		goto re_enumerate;
+	}
 	ret = usb_control_msg(udev, usb_sndctrlpipe(udev, 0),
 			USB_REQ_SET_CONFIGURATION, 0,
 			udev->actconfig->desc.bConfigurationValue, 0,
@@ -3650,8 +3661,10 @@ static int usb_reset_and_verify_device(struct usb_device *udev)
 		dev_err(&udev->dev,
 			"can't restore configuration #%d (error=%d)\n",
 			udev->actconfig->desc.bConfigurationValue, ret);
+		mutex_unlock(&hcd->bandwidth_mutex);
 		goto re_enumerate;
   	}
+	mutex_unlock(&hcd->bandwidth_mutex);
 	usb_set_device_state(udev, USB_STATE_CONFIGURED);
 
 	/* Put interfaces back into the same altsettings as before.
@@ -3661,7 +3674,8 @@ static int usb_reset_and_verify_device(struct usb_device *udev)
 	 * endpoint state.
 	 */
 	for (i = 0; i < udev->actconfig->desc.bNumInterfaces; i++) {
-		struct usb_interface *intf = udev->actconfig->interface[i];
+		struct usb_host_config *config = udev->actconfig;
+		struct usb_interface *intf = config->interface[i];
 		struct usb_interface_descriptor *desc;
 
 		desc = &intf->cur_altsetting->desc;
@@ -3670,6 +3684,17 @@ static int usb_reset_and_verify_device(struct usb_device *udev)
 			usb_enable_interface(udev, intf, true);
 			ret = 0;
 		} else {
+			/* We've just reset the device, so it will think alt
+			 * setting 0 is installed.  For usb_set_interface() to
+			 * work properly, we need to set the current alternate
+			 * interface setting to 0 (or the first alt setting, if
+			 * the device doesn't have alt setting 0).
+			 */
+			intf->cur_altsetting =
+				usb_find_alt_setting(config, i, 0);
+			if (!intf->cur_altsetting)
+				intf->cur_altsetting =
+					&config->intf_cache[i]->altsetting[0];
 			ret = usb_set_interface(udev, desc->bInterfaceNumber,
 					desc->bAlternateSetting);
 		}