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authorSarah Sharp <sarah.a.sharp@linux.intel.com>2009-04-28 06:57:50 +0400
committerGreg Kroah-Hartman <gregkh@suse.de>2009-06-16 08:44:49 +0400
commit6d65b78a093552fb42448480d4c66bf093a6d4cf (patch)
tree38d5797b9cdd60421d6b28db225d34c9f2e56f6f /include/linux/usb.h
parent3ffbba9511b4148cbe1f6b6238686adaeaca8feb (diff)
downloadlinux-6d65b78a093552fb42448480d4c66bf093a6d4cf.tar.xz
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>
Diffstat (limited to 'include/linux/usb.h')
-rw-r--r--include/linux/usb.h4
1 files changed, 3 insertions, 1 deletions
diff --git a/include/linux/usb.h b/include/linux/usb.h
index 475cb75cc378..112a2d6e922f 100644
--- a/include/linux/usb.h
+++ b/include/linux/usb.h
@@ -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