Commit 6d65b78a authored Apr 27, 2009 by Sarah Sharp Committed by Greg Kroah-Hartman Jun 15, 2009

USB: Support for submitting control URBs under xHCI.

Warn users of URB_NO_SETUP_DMA_MAP about xHCI behavior.

Device drivers can choose to DMA map the setup packet of a control transfer
before submitting the URB to the USB core. Drivers then set the
URB_NO_SETUP_DMA_MAP and pass in the DMA memory address in setup_dma, instead of
providing a kernel address for setup_packet. However, xHCI requires that the
setup packet be copied into an internal data structure, and we need a kernel
memory address pointer for that. Warn users of URB_NO_SETUP_DMA_MAP that they
should provide a valid pointer for setup_packet, along with the DMA address.

FIXME: I'm not entirely sure how to work around this in the xHCI driver
or USB core.

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

parent 3ffbba95

include/linux/usb.h

+3 −1

Original line number	Diff line number	Diff line
		@@ -1044,7 +1044,9 @@ typedef void (usb_complete_t)(struct urb );
		* @setup_dma: For control transfers with URB_NO_SETUP_DMA_MAP set, the
		* device driver has provided this DMA address for the setup packet.
		* The host controller driver should use this in preference to
		* setup_packet.
		* setup_packet, but the HCD may chose to ignore the address if it must
		* copy the setup packet into internal structures. Therefore, setup_packet
		* must always point to a valid buffer.
		* @start_frame: Returns the initial frame for isochronous transfers.
		* @number_of_packets: Lists the number of ISO transfer buffers.
		* @interval: Specifies the polling interval for interrupt or isochronous

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