Re: [linuxsh-shmedia-dev] sh64 support for Tekram DC-390U3W

[Paul M. <le...@li...>]

On Fri, Jun 27, 2003 at 04:26:05PM +0100, Richard Curnow wrote:
> I've now got stuck because I got lost trying to follow the call chain
> back far enough to locate where the scatter-gather buffers are getting
> allocated and hence why the addresses in the table passed to pci_map_sg
> are all zero.  I suspect there's something in asm-sh64 or arch/sh64
> that's missing a real implementation, but I've no idea what.
>=20
> Is anybody au fait with this area of the code and able to give me any
> pointers where to look next?
>=20
There's absolutely nothing wrong with getting a NULL address in this case,
the existing code just doesn't deal with it properly.

Drivers have two options for dealing with this, they can either set
->address or they can set ->page and ->offset, the latter of which is the
preferred method, and is the only thing that works for highmem systems.

Try out this patch (I haven't tried compiling it yet, but its a proof of
concept .. you may also have to adjust some of the flushing), and see if
it works for you..

--- shmedia-2.4/include/asm-sh64/scatterlist.h	Tue May 13 15:08:57 2003
+++ shmedia-2.4.test/include/asm-sh64/scatterlist.h	Fri Jun 27 11:58:22 2003
@@ -23,12 +23,13 @@
 #define _ASM_SH64_SCATTERLIST_H
=20
 struct scatterlist {
-    char *address;	     /* Location data is to be transferred to */
-    char *alt_address;	 /* Location of actual if address is a    */
-			                   /* dma indirect buffer.  NULL otherwise  */
-    struct page	*page;	 /* Location for highmem page, if any */
-		unsigned int offset; /* for highmem, page offset */
-    unsigned int length;
+	char *address;		/* Location data is to be transferred to, NULL
+    				   for highmem page */
+	struct page *page;	/* Location for highmem page, if any */
+	unsigned int offset;	/* for highmem, page offset */
+
+	dma_addr_t dma_address;
+	unsigned int length;
 };
=20
 #define ISA_DMA_THRESHOLD (0xffffffff)
--- shmedia-2.4/include/asm-sh64/pci.h	Fri Jun 20 18:44:48 2003
+++ shmedia-2.4.test/include/asm-sh64/pci.h	Fri Jun 27 12:05:26 2003
@@ -141,8 +141,18 @@
 			     int nents,int direction)
 {
 	int i;
-	for (i=3D0; i<nents; i++)
-		dma_cache_wback_inv((unsigned long)sg[i].address, sg[i].length);=20
+
+	for (i =3D 0; i < nents; i++) {
+		if (sg[i].address) {
+			dma_cache_wback_inv((unsigned long)sg[i].address,
+					    sg[i].length);
+			sg[i].dma_address =3D virt_to_bus(sg[i].address);
+		} else {
+			sg[i].dma_address =3D page_to_bus(sg[i].page) +
+					    sg[i].offset;
+		}
+	}
+
 	return nents;
 }
=20
@@ -155,7 +165,17 @@
 static inline void pci_unmap_sg(struct pci_dev *hwdev, struct scatterlist =
*sg,
 				int nents,int direction)
 {
-	/* Nothing to do */
+	int i;
+
+	if (direction =3D=3D PCI_DMA_TODEVICE)
+		return;
+=09
+	for (i =3D 0; i < nents; i++) {
+		if (!sg[i].address)
+			continue;
+
+		dma_cache_wback_inv((unsigned long)sg[i].address, sg[i].length);
+	}
 }
=20
=20
@@ -188,7 +208,10 @@
 				   struct scatterlist *sg,
 				   int nelems,int direction)
 {
-	/* Nothing to do */
+	int i;
+
+	for (i =3D 0; i < nelems; i++)
+		dma_cache_wback_inv((unsigned long)sg[i].address, sg[i].length);
 }
=20
=20
@@ -219,7 +242,7 @@
 ** returns, or alternatively stop on the first sg_dma_len(sg) which
 ** is 0.
 */
-#define sg_dma_address(sg)      (virt_to_bus((sg)->address))
+#define sg_dma_address(sg)      ((sg)->dma_address)
 #define sg_dma_len(sg)          ((sg)->length)
=20
 #define PCI_DMA_BUS_IS_PHYS	(1)