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authorSarah Sharp <sarah.a.sharp@linux.intel.com>2009-04-27 19:53:56 -0700
committerGreg Kroah-Hartman <gregkh@suse.de>2009-06-15 21:44:48 -0700
commit7f84eef0dafb1d318263d8b71c38700aaf2d530d (patch)
treed7de1ac3d91fb206a5cec2e85b0ad7f4a7b78b21 /drivers/usb/core/hub.c
parenta74588f94655263b96dacbbf14aac0958d8b7409 (diff)
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USB: xhci: No-op command queueing and irq handler.
xHCI host controllers can optionally implement a no-op test. This simple test ensures the OS has correctly setup all basic data structures and can correctly respond to interrupts from the host controller hardware. There are two rings exercised by the no-op test: the command ring, and the event ring. The host controller driver writes a no-op command TRB to the command ring, and rings the doorbell for the command ring (the first entry in the doorbell array). The hardware receives this event, places a command completion event on the event ring, and fires an interrupt. The host controller driver sees the interrupt, and checks the event ring for TRBs it can process, and sees the command completion event. (See the rules in xhci-ring.c for who "owns" a TRB. This is a simplified set of rules, and may not contain all the details that are in the xHCI 0.95 spec.) A timer fires every 60 seconds to debug the state of the hardware and command and event rings. This timer only runs if CONFIG_USB_XHCI_HCD_DEBUGGING is 'y'. Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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