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Date:      Wed, 19 Aug 2009 14:39:08 +0000 (UTC)
From:      Rafal Jaworowski <raj@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r196380 - head/sys/dev/usb
Message-ID:  <200908191439.n7JEd892057035@svn.freebsd.org>
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Author: raj
Date: Wed Aug 19 14:39:08 2009
New Revision: 196380
URL: http://svn.freebsd.org/changeset/base/196380

Log:
  Fix USB cache sync operations for platforms with non-coherent DMA.
  
  - usb_pc_cpu_invalidate() is called between [consecutive] reads from a device,
    so a sequence of BUS_DMASYNC_POSTREAD and _PREREAD should be used. Note we
    cannot use or'ed shorthand ( _POSTREAD | _PREREAD) for BUS_DMASYNC flags, as
    the low level bus dma sync operation is implementation dependent and we
    cannot assume the required order of operations to be guaranteed.
  
  - usb_pc_cpu_flush() is called before writing to a device, so
    BUS_DMASYNC_PREWRITE should be used.
  
  Submitted by:	Grzegorz Bernacki
  Reviewed by:	HPS, arm@, usb@ ML
  Tested by:	HPS, Mike Tancsa
  Approved by:	re (kib)
  Obtained from:	Semihalf

Modified:
  head/sys/dev/usb/usb_busdma.c

Modified: head/sys/dev/usb/usb_busdma.c
==============================================================================
--- head/sys/dev/usb/usb_busdma.c	Wed Aug 19 14:38:43 2009	(r196379)
+++ head/sys/dev/usb/usb_busdma.c	Wed Aug 19 14:39:08 2009	(r196380)
@@ -679,8 +679,8 @@ usb_pc_cpu_invalidate(struct usb_page_ca
 		/* nothing has been loaded into this page cache! */
 		return;
 	}
-	bus_dmamap_sync(pc->tag, pc->map,
-	    BUS_DMASYNC_POSTWRITE | BUS_DMASYNC_POSTREAD);
+	bus_dmamap_sync(pc->tag, pc->map, BUS_DMASYNC_POSTREAD);
+	bus_dmamap_sync(pc->tag, pc->map, BUS_DMASYNC_PREREAD);
 }
 
 /*------------------------------------------------------------------------*
@@ -693,8 +693,7 @@ usb_pc_cpu_flush(struct usb_page_cache *
 		/* nothing has been loaded into this page cache! */
 		return;
 	}
-	bus_dmamap_sync(pc->tag, pc->map,
-	    BUS_DMASYNC_PREWRITE | BUS_DMASYNC_PREREAD);
+	bus_dmamap_sync(pc->tag, pc->map, BUS_DMASYNC_PREWRITE);
 }
 
 /*------------------------------------------------------------------------*

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