PERFORCE change 155927 for review

[Hans Petter Selasky]

http://perforce.freebsd.org/chv.cgi?CH=155927

Change 155927 by hselasky at hselasky_laptop001 on 2009/01/10 18:35:24

	
	Like Marcel Moolenaar has pointed out, we can unconditionally
	preserve the page offset, hence on platforms without DMA
	bouncing this is always the case.
	
	Repeating the background for this:
	
	/*
	 * Background: Some kinds of DMA hardware only store the full
	 * physical address of the first memory page when multiple memory
	 * pages are loaded into DMA. For consecutive memory pages, only the
	 * non-offset part of the physical address is updated. The hardware
	 * computes the amount of data that should be stored in the first
	 * memory page from the minimum of the total transfer length and
	 * PAGE_SIZE, minus the initial page offset. When the initial page
	 * offset is not preserved, the hardware ends up transferring an
	 * invalid number of bytes to or from the initial memory page.
	 */

Affected files ...

.. //depot/projects/usb/src/sys/amd64/amd64/busdma_machdep.c#10 edit
.. //depot/projects/usb/src/sys/arm/arm/busdma_machdep.c#12 edit
.. //depot/projects/usb/src/sys/i386/i386/busdma_machdep.c#13 edit
.. //depot/projects/usb/src/sys/ia64/ia64/busdma_machdep.c#9 edit
.. //depot/projects/usb/src/sys/sys/bus_dma.h#7 edit

Differences ...

==== //depot/projects/usb/src/sys/amd64/amd64/busdma_machdep.c#10 (text+ko) ====

@@ -1128,17 +1128,11 @@
 	bz->active_bpages++;
 	mtx_unlock(&bounce_lock);
 
-	/* reset page offset */
+	/* page offset needs to be preserved */
 	bpage->vaddr &= ~PAGE_MASK;
 	bpage->busaddr &= ~PAGE_MASK;
-
-	if (BUS_DMA_NO_REALIGN(dmat->alignment, dmat->boundary,
-	    dmat->maxsegsz)) {
-		/* preserve page offset */
-		bpage->vaddr |= vaddr & PAGE_MASK;
-		bpage->busaddr |= vaddr & PAGE_MASK;
-	}
-
+	bpage->vaddr |= vaddr & PAGE_MASK;
+	bpage->busaddr |= vaddr & PAGE_MASK;
 	bpage->datavaddr = vaddr;
 	bpage->datacount = size;
 	STAILQ_INSERT_TAIL(&(map->bpages), bpage, links);

==== //depot/projects/usb/src/sys/arm/arm/busdma_machdep.c#12 (text+ko) ====

@@ -1415,17 +1415,11 @@
 	bz->active_bpages++;
 	mtx_unlock(&bounce_lock);
 
-	/* reset page offset */
+	/* page offset needs to be preserved */
 	bpage->vaddr &= ~PAGE_MASK;
 	bpage->busaddr &= ~PAGE_MASK;
-
-	if (BUS_DMA_NO_REALIGN(dmat->alignment, dmat->boundary,
-	    dmat->maxsegsz)) {
-		/* preserve page offset */
-		bpage->vaddr |= vaddr & PAGE_MASK;
-		bpage->busaddr |= vaddr & PAGE_MASK;
-	}
-
+	bpage->vaddr |= vaddr & PAGE_MASK;
+	bpage->busaddr |= vaddr & PAGE_MASK;
 	bpage->datavaddr = vaddr;
 	bpage->datacount = size;
 	STAILQ_INSERT_TAIL(&(map->bpages), bpage, links);

==== //depot/projects/usb/src/sys/i386/i386/busdma_machdep.c#13 (text+ko) ====

@@ -1146,17 +1146,11 @@
 	bz->active_bpages++;
 	mtx_unlock(&bounce_lock);
 
-	/* reset page offset */
+	/* page offset needs to be preserved */
 	bpage->vaddr &= ~PAGE_MASK;
 	bpage->busaddr &= ~PAGE_MASK;
-
-	if (BUS_DMA_NO_REALIGN(dmat->alignment, dmat->boundary,
-	    dmat->maxsegsz)) {
-		/* preserve page offset */
-		bpage->vaddr |= vaddr & PAGE_MASK;
-		bpage->busaddr |= vaddr & PAGE_MASK;
-	}
-
+	bpage->vaddr |= vaddr & PAGE_MASK;
+	bpage->busaddr |= vaddr & PAGE_MASK;
 	bpage->datavaddr = vaddr;
 	bpage->datacount = size;
 	STAILQ_INSERT_TAIL(&(map->bpages), bpage, links);

==== //depot/projects/usb/src/sys/ia64/ia64/busdma_machdep.c#9 (text+ko) ====

@@ -936,16 +936,11 @@
 	active_bpages++;
 	mtx_unlock(&bounce_lock);
 
-	/* reset page offset */
+	/* page offset needs to be preserved */
 	bpage->vaddr &= ~PAGE_MASK;
 	bpage->busaddr &= ~PAGE_MASK;
-
-	if (BUS_DMA_NO_REALIGN(dmat->alignment, dmat->boundary,
-	    dmat->maxsegsz)) {
-		/* preserve page offset */
-		bpage->vaddr |= vaddr & PAGE_MASK;
-		bpage->busaddr |= vaddr & PAGE_MASK;
-	}
+	bpage->vaddr |= vaddr & PAGE_MASK;
+	bpage->busaddr |= vaddr & PAGE_MASK;
 
 	bpage->datavaddr = vaddr;
 	bpage->datacount = size;

==== //depot/projects/usb/src/sys/sys/bus_dma.h#7 (text+ko) ====

@@ -102,24 +102,6 @@
 #define	BUS_DMA_NOWRITE		0x100
 #define	BUS_DMA_NOCACHE		0x200
 
-/*
- * The following flag specifies that no re-alignment of individual
- * memory pages is allowed when loaded into DMA. It can only be used
- * when "maxsegsz" is equal to "PAGE_SIZE" and "alignment" is less
- * than or equal to 1.
- *
- * Background: Some kinds of DMA hardware only stores the full
- * physical address of the first memory page when multiple memory
- * pages are loaded into DMA. Consequtive memory pages only gets the
- * non-offset part of the physical address updated. The hardware
- * computes the amount of data that should be stored in the first
- * memory page from the minimum of the total transfer length and
- * PAGE_SIZE minus the initial page offset. When the initial page
- * offset is not preserved the hardware ends up transferring an
- * invalid number of bytes to or from the initial memory page.
- */
-#define	BUS_DMA_NOREAL		0x400	/* no page re-alignment allowed */
-
 /* Forwards needed by prototypes below. */
 struct mbuf;
 struct uio;
@@ -133,23 +115,6 @@
 #define	BUS_DMASYNC_POSTWRITE	8
 
 /*
- * Background: Some kinds of DMA hardware only store the full
- * physical address of the first memory page when multiple memory
- * pages are loaded into DMA. For consecutive memory pages, only the
- * non-offset part of the physical address is updated. The hardware
- * computes the amount of data that should be stored in the first
- * memory page from the minimum of the total transfer length and
- * PAGE_SIZE, minus the initial page offset. When the initial page
- * offset is not preserved, the hardware ends up transferring an
- * invalid number of bytes to or from the initial memory page.
- *
- * The following macro returns true when the initial page offset must
- * be preserved:
- */
-#define	BUS_DMA_NO_REALIGN(align,boundary,maxsegsz) \
-  (((align) == 1) && ((boundary) == PAGE_SIZE) && ((maxsegsz) == PAGE_SIZE))
-
-/*
  *	bus_dma_segment_t
  *
  *	Describes a single contiguous DMA transaction.  Values