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authorSarah Sharp <sarah.a.sharp@linux.intel.com>2009-12-03 09:44:36 -0800
committerGreg Kroah-Hartman <gregkh@suse.de>2009-12-11 11:55:27 -0800
commit3f0479e00a3fca9590ae8d9edc4e9c47b7fa0610 (patch)
tree495cee9f35ed0315367a10af86bbb107f05eeb75 /arch/arm/mach-mv78xx0/common.h
parent91017f9cf5fcfb601b8d583c896ac7de7d200c57 (diff)
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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>
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