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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>
This commit is contained in:
Sarah Sharp 2009-04-27 19:57:50 -07:00 committed by Greg Kroah-Hartman
parent 3ffbba9511
commit 6d65b78a09
1 changed files with 3 additions and 1 deletions
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4
include/linux/usb.h
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@ -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