---

yaml
---
r: 58705
b: refs/heads/master
c: a5bf5f5
h: refs/heads/master
i:
  58703: 721515b
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: dab632e8c483532bd84e1f3401c72612e39a7c40
+refs/heads/master: a5bf5f5a370ba7c10f5362265e360952145a7da1

trunk/drivers/ata/ata_piix.c

@@ -685,21 +685,29 @@ static void piix_set_piomode (struct ata_port *ap, struct ata_device *adev)
 	if (adev->class == ATA_DEV_ATA)
 		control |= 4;	/* PPE enable */
 
+	/* PIO configuration clears DTE unconditionally.  It will be
+	 * programmed in set_dmamode which is guaranteed to be called
+	 * after set_piomode if any DMA mode is available.
+	 */
 	pci_read_config_word(dev, master_port, &master_data);
 	if (is_slave) {
+		/* clear TIME1|IE1|PPE1|DTE1 */
+		master_data &= 0xff0f;
 		/* Enable SITRE (seperate slave timing register) */
 		master_data |= 0x4000;
 		/* enable PPE1, IE1 and TIME1 as needed */
 		master_data |= (control << 4);
 		pci_read_config_byte(dev, slave_port, &slave_data);
 		slave_data &= (ap->port_no ? 0x0f : 0xf0);
 		/* Load the timing nibble for this slave */
-		slave_data |= ((timings[pio][0] << 2) | timings[pio][1]) << (ap->port_no ? 4 : 0);
+		slave_data |= ((timings[pio][0] << 2) | timings[pio][1])
+						<< (ap->port_no ? 4 : 0);
 	} else {
-		/* Master keeps the bits in a different format */
-		master_data &= 0xccf8;
+		/* clear ISP|RCT|TIME0|IE0|PPE0|DTE0 */
+		master_data &= 0xccf0;
 		/* Enable PPE, IE and TIME as appropriate */
 		master_data |= control;
+		/* load ISP and RCT */
 		master_data |=
 			(timings[pio][0] << 12) |
 			(timings[pio][1] << 8);
@@ -816,7 +824,7 @@ static void do_pata_set_dmamode (struct ata_port *ap, struct ata_device *adev, i
 			master_data &= 0xFF4F;  /* Mask out IORDY|TIME1|DMAONLY */
 			master_data |= control << 4;
 			pci_read_config_byte(dev, 0x44, &slave_data);
-			slave_data &= (0x0F + 0xE1 * ap->port_no);
+			slave_data &= (ap->port_no ? 0x0f : 0xf0);
 			/* Load the matching timing */
 			slave_data |= ((timings[pio][0] << 2) | timings[pio][1]) << (ap->port_no ? 4 : 0);
 			pci_write_config_byte(dev, 0x44, slave_data);
@@ -828,8 +836,11 @@ static void do_pata_set_dmamode (struct ata_port *ap, struct ata_device *adev, i
 				(timings[pio][0] << 12) |
 				(timings[pio][1] << 8);
 		}
-		udma_enable &= ~(1 << devid);
-		pci_write_config_word(dev, master_port, master_data);
+
+		if (ap->udma_mask) {
+			udma_enable &= ~(1 << devid);
+			pci_write_config_word(dev, master_port, master_data);
+		}
 	}
 	/* Don't scribble on 0x48 if the controller does not support UDMA */
 	if (ap->udma_mask)