--- ../linux-2.4.5-ac3-clean/drivers/ide/ide.c	Mon May 28 20:28:05 2001
+++ drivers/ide/ide.c	Mon May 28 20:21:48 2001
@@ -543,10 +543,20 @@
 {
 	struct request *rq;
 	unsigned long flags;
+	ide_drive_t *drive = hwgroup->drive;
 
 	spin_lock_irqsave(&io_request_lock, flags);
 	rq = hwgroup->rq;
 
+	/*
+	 * decide whether to reenable DMA -- 3 is a random magic for now,
+	 * if we DMA timeout more than 3 times, just stay in PIO
+	 */
+	if (drive->state == DMA_PIO_RETRY && drive->retry_pio <= 3) {
+		drive->state = 0;
+		hwgroup->hwif->dmaproc(ide_dma_on, drive);
+	}
+
 	if (!end_that_request_first(rq, uptodate, hwgroup->drive->name)) {
 		add_blkdev_randomness(MAJOR(rq->rq_dev));
 		blkdev_dequeue_request(rq);
@@ -1419,6 +1429,49 @@
 }
 
 /*
+ * un-busy the hwgroup etc, and clear any pending DMA status. we want to
+ * retry the current request in pio mode instead of risking tossing it
+ * all away
+ */
+void ide_dma_timeout_retry(ide_drive_t *drive)
+{
+	ide_hwif_t *hwif = HWIF(drive);
+	struct request *rq;
+
+	/*
+	 * end current dma transaction
+	 */
+	(void) hwif->dmaproc(ide_dma_end, drive);
+
+	/*
+	 * complain a little, later we might remove some of this verbosity
+	 */
+	printk("%s: timeout waiting for DMA\n", drive->name);
+	(void) hwif->dmaproc(ide_dma_timeout, drive);
+
+	/*
+	 * disable dma for now, but remember that we did so because of
+	 * a timeout -- we'll reenable after we finish this next request
+	 * (or rather the first chunk of it) in pio.
+	 */
+	drive->retry_pio++;
+	drive->state = DMA_PIO_RETRY;
+	(void) hwif->dmaproc(ide_dma_off_quietly, drive);
+
+	/*
+	 * un-busy drive etc (hwgroup->busy is cleared on return) and
+	 * make sure request is sane
+	 */
+	rq = HWGROUP(drive)->rq;
+	HWGROUP(drive)->rq = NULL;
+
+	rq->errors = 0;
+	rq->sector = rq->bh->b_rsector;
+	rq->current_nr_sectors = rq->bh->b_size >> 9;
+	rq->buffer = rq->bh->b_data;
+}
+
+/*
  * ide_timer_expiry() is our timeout function for all drive operations.
  * But note that it can also be invoked as a result of a "sleep" operation
  * triggered by the mod_timer() call in ide_do_request.
@@ -1491,11 +1544,10 @@
 				startstop = handler(drive);
 			} else {
 				if (drive->waiting_for_dma) {
-					(void) hwgroup->hwif->dmaproc(ide_dma_end, drive);
-					printk("%s: timeout waiting for DMA\n", drive->name);
-					(void) hwgroup->hwif->dmaproc(ide_dma_timeout, drive);
-				}
-				startstop = ide_error(drive, "irq timeout", GET_STAT());
+					startstop = ide_stopped;
+					ide_dma_timeout_retry(drive);
+				} else
+					startstop = ide_error(drive, "irq timeout", GET_STAT());
 			}
 			set_recovery_timer(hwif);
 			drive->service_time = jiffies - drive->service_start;
--- ../linux-2.4.5-ac3-clean/include/linux/ide.h	Mon May 28 20:28:13 2001
+++ include/linux/ide.h	Mon May 28 20:21:18 2001
@@ -87,6 +87,11 @@
 #define ERROR_RECAL	1	/* Recalibrate every 2nd retry */
 
 /*
+ * state flags
+ */
+#define DMA_PIO_RETRY	1	/* retrying in PIO */
+
+/*
  * Ensure that various configuration flags have compatible settings
  */
 #ifdef REALLY_SLOW_IO
@@ -299,6 +304,8 @@
 	special_t	special;	/* special action flags */
 	byte     keep_settings;		/* restore settings after drive reset */
 	byte     using_dma;		/* disk is using dma for read/write */
+	byte	 retry_pio;		/* retrying dma capable host in pio */
+	byte	 state;			/* retry state */
 	byte     waiting_for_dma;	/* dma currently in progress */
 	byte     unmask;		/* flag: okay to unmask other irqs */
 	byte     slow;			/* flag: slow data port */