svn commit: r291250 - stable/10/sys/dev/usb

[Hans Petter Selasky]

Author: hselasky
Date: Tue Nov 24 12:17:00 2015
New Revision: 291250
URL: https://svnweb.freebsd.org/changeset/base/291250

Log:
  MFC r290326:
  Relax the BUS_DMA_KEEP_PG_OFFSET requirement to allow optimising
  allocation of DMA bounce buffers.
  
  Discussed with:	ian @

Modified:
  stable/10/sys/dev/usb/usb_busdma.c
Directory Properties:
  stable/10/   (props changed)

Modified: stable/10/sys/dev/usb/usb_busdma.c
==============================================================================
--- stable/10/sys/dev/usb/usb_busdma.c	Tue Nov 24 12:11:56 2015	(r291249)
+++ stable/10/sys/dev/usb/usb_busdma.c	Tue Nov 24 12:17:00 2015	(r291250)
@@ -474,9 +474,13 @@ usb_pc_common_mem_cb(void *arg, bus_dma_
 	pc->page_offset_buf = rem;
 	pc->page_offset_end += rem;
 #ifdef USB_DEBUG
-	if (rem != (USB_P2U(pc->buffer) & (USB_PAGE_SIZE - 1))) {
+	if (nseg > 1 &&
+	    ((segs->ds_addr + segs->ds_len) & (USB_PAGE_SIZE - 1)) !=
+	    ((segs + 1)->ds_addr & (USB_PAGE_SIZE - 1))) {
 		/*
-		 * This check verifies that the physical address is correct:
+		 * This check verifies there is no page offset hole
+		 * between the first and second segment. See the
+		 * BUS_DMA_KEEP_PG_OFFSET flag.
 		 */
 		DPRINTFN(0, "Page offset was not preserved\n");
 		error = 1;