libata: ignore deverr on SETXFER if mode is configured

index bdbd55a..bcd2860 100644
@@ -3048,6 +3048,8 @@ int ata_down_xfermask_limit(struct ata_device *dev, unsigned int sel)
 static int ata_dev_set_mode(struct ata_device *dev)
 {
 	struct ata_eh_context *ehc = &dev->link->eh_context;
+	const char *dev_err_whine = "";
+	int ign_dev_err = 0;
 	unsigned int err_mask;
 	int rc;
 

@@ -3057,41 +3059,57 @@ static int ata_dev_set_mode(struct ata_device *dev)
 
 	err_mask = ata_dev_set_xfermode(dev);
 
+	if (err_mask & ~AC_ERR_DEV)
+		goto fail;
+
+	/* revalidate */
+	ehc->i.flags |= ATA_EHI_POST_SETMODE;
+	rc = ata_dev_revalidate(dev, ATA_DEV_UNKNOWN, 0);
+	ehc->i.flags &= ~ATA_EHI_POST_SETMODE;
+	if (rc)
+		return rc;
+
 	/* Old CFA may refuse this command, which is just fine */
 	if (dev->xfer_shift == ATA_SHIFT_PIO && ata_id_is_cfa(dev->id))
-		err_mask &= ~AC_ERR_DEV;
+		ign_dev_err = 1;
 
 	/* Some very old devices and some bad newer ones fail any kind of
 	   SET_XFERMODE request but support PIO0-2 timings and no IORDY */
 	if (dev->xfer_shift == ATA_SHIFT_PIO && !ata_id_has_iordy(dev->id) &&
 			dev->pio_mode <= XFER_PIO_2)
-		err_mask &= ~AC_ERR_DEV;
+		ign_dev_err = 1;
 
 	/* Early MWDMA devices do DMA but don't allow DMA mode setting.
 	   Don't fail an MWDMA0 set IFF the device indicates it is in MWDMA0 */
 	if (dev->xfer_shift == ATA_SHIFT_MWDMA &&
 	    dev->dma_mode == XFER_MW_DMA_0 &&
 	    (dev->id[63] >> 8) & 1)
-		err_mask &= ~AC_ERR_DEV;
+		ign_dev_err = 1;
 
-	if (err_mask) {
-		ata_dev_printk(dev, KERN_ERR, "failed to set xfermode "
-			       "(err_mask=0x%x)\n", err_mask);
-		return -EIO;
-	}
+	/* if the device is actually configured correctly, ignore dev err */
+	if (dev->xfer_mode == ata_xfer_mask2mode(ata_id_xfermask(dev->id)))
+		ign_dev_err = 1;
 
-	ehc->i.flags |= ATA_EHI_POST_SETMODE;
-	rc = ata_dev_revalidate(dev, ATA_DEV_UNKNOWN, 0);
-	ehc->i.flags &= ~ATA_EHI_POST_SETMODE;
-	if (rc)
-		return rc;
+	if (err_mask & AC_ERR_DEV) {
+		if (!ign_dev_err)
+			goto fail;
+		else
+			dev_err_whine = " (device error ignored)";
+	}
 
 	DPRINTK("xfer_shift=%u, xfer_mode=0x%x\n",
 		dev->xfer_shift, (int)dev->xfer_mode);
 
-	ata_dev_printk(dev, KERN_INFO, "configured for %s\n",
-		       ata_mode_string(ata_xfer_mode2mask(dev->xfer_mode)));
+	ata_dev_printk(dev, KERN_INFO, "configured for %s%s\n",
+		       ata_mode_string(ata_xfer_mode2mask(dev->xfer_mode)),
+		       dev_err_whine);
+
 	return 0;
+
+ fail:
+	ata_dev_printk(dev, KERN_ERR, "failed to set xfermode "
+		       "(err_mask=0x%x)\n", err_mask);
+	return -EIO;
 }
 
 /**