[PATCH 1/1] libata-dev-2.6: pdc2027x ATAPI DMA fix

[Albert Lee <albertcc@tw.ibm.com>]

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Jeff,

   pdc2027x: pdc2027x ATAPI DMA fix.
The previous (request_bufflen % 256) ATAPI DMA rule still fails and causes timeout in some case.

Changes:
- Only turn on pdc2027x ATAPI DMA for READ/WRITE and (request_bufflen % 1024 == 0) for safty.

Attached please find the patch against the libata-dev-2.6 tree for your review. Thanks.

Albert

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--- libata-dev-2.6-pll-fix/drivers/scsi/pata_pdc2027x.c	2005-04-11 15:05:42.000000000 +0800
+++ libata-dev-2.6-dma_fix/drivers/scsi/pata_pdc2027x.c	2005-04-16 08:59:34.000000000 +0800
@@ -29,7 +29,7 @@
 #include <asm/io.h>
 
 #define DRV_NAME	"pata_pdc2027x"
-#define DRV_VERSION	"0.60"
+#define DRV_VERSION	"0.61"
 #undef PDC_DEBUG
 
 #ifdef PDC_DEBUG
@@ -445,11 +445,26 @@
 static int pdc2027x_check_atapi_dma(struct ata_queued_cmd *qc)
 {
 	struct scsi_cmnd *cmd = qc->scsicmd;
-	int rc = 0;
+	u8 *scsicmd = cmd->cmnd;
+	int rc = 1; /* atapi dma off by default */
 
-	/* pdc2027x can only do ATAPI DMA for specific buffer size */
-	if (cmd->request_bufflen % 256)
-		rc = 1;
+	switch (scsicmd[0]) {
+	case READ_6:
+	case READ_10:
+	case READ_12:
+	case READ_16:
+
+	case WRITE_6:
+	case WRITE_10:
+	case WRITE_12:
+	case WRITE_16:
+		/* pdc2027x can only do ATAPI DMA for specific buffer size */
+		if (cmd->request_bufflen % 1024 == 0)
+			rc = 0;
+		break;
+	default:
+		;
+	}
 
 	return rc;
 }