Mark Lord wrote:
I think this original patch still applies cleanly on at least 2.6.23-rc7.

Drain up to 512 words from host/bridge FIFO on stuck DRQ HSM violation,
rather than just getting stuck there forever.

Signed-off-by: Mark Lord <[EMAIL PROTECTED]>
---

--- old/drivers/ata/libata-sff.c    2007-09-28 09:29:22.000000000 -0400
+++ linux/drivers/ata/libata-sff.c    2007-09-28 09:39:44.000000000 -0400
@@ -420,6 +420,28 @@
    ap->ops->irq_on(ap);
}

+static void ata_drain_fifo(struct ata_port *ap, struct ata_queued_cmd *qc)
+{
+    u8 stat = ata_chk_status(ap);
+    /*
+     * Try to clear stuck DRQ if necessary,
+     * by reading/discarding up to two sectors worth of data.
+     */
+    if ((stat & ATA_DRQ) && (!qc || qc->dma_dir != DMA_TO_DEVICE)) {
+        unsigned int i;
+        unsigned int limit = qc ? qc->sect_size : ATA_SECT_SIZE;
+
+        printk(KERN_WARNING "Draining up to %u words from data FIFO.\n",
+                                    limit);
+        for (i = 0; i < limit ; ++i) {
+            ioread16(ap->ioaddr.data_addr);
+            if (!(ata_chk_status(ap) & ATA_DRQ))
+                break;
+        }
+        printk(KERN_WARNING "Drained %u/%u words.\n", i, limit);
+    }
+}
+
/**
* ata_bmdma_drive_eh - Perform EH with given methods for BMDMA controller
 *    @ap: port to handle error for
@@ -476,7 +498,7 @@
    }

    ata_altstatus(ap);
-    ata_chk_status(ap);
+    ata_drain_fifo(ap, qc);
    ap->ops->irq_clear(ap);

    spin_unlock_irqrestore(ap->lock, flags);

applied, after hand-editing out the top of the message, so that it would not be copied into the kernel changelog

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