diff --git a/drivers/ide/pci/cmd64x.c b/drivers/ide/pci/cmd64x.c
index b0d4825c56a9c45040dc062d05b185b2358869cd..561197f7b5bb92de6ae208d138cefaf6f9755082 100644
--- a/drivers/ide/pci/cmd64x.c
+++ b/drivers/ide/pci/cmd64x.c
@@ -1,6 +1,6 @@
 /* $Id: cmd64x.c,v 1.21 2000/01/30 23:23:16
  *
- * linux/drivers/ide/pci/cmd64x.c		Version 1.41	Feb 3, 2007
+ * linux/drivers/ide/pci/cmd64x.c		Version 1.42	Feb 8, 2007
  *
  * cmd64x.c: Enable interrupts at initialization time on Ultra/PCI machines.
  *           Note, this driver is not used at all on other systems because
@@ -189,6 +189,11 @@ static int cmd64x_get_info (char *buffer, char **addr, off_t offset, int count)
 
 #endif	/* defined(DISPLAY_CMD64X_TIMINGS) && defined(CONFIG_PROC_FS) */
 
+static u8 quantize_timing(int timing, int quant)
+{
+	return (timing + quant - 1) / quant;
+}
+
 /*
  * This routine writes the prepared setup/active/recovery counts
  * for a drive into the cmd646 chipset registers to active them.
@@ -268,47 +273,37 @@ static void program_drive_counts (ide_drive_t *drive, int setup_count, int activ
  */
 static u8 cmd64x_tune_pio (ide_drive_t *drive, u8 mode_wanted)
 {
-	int setup_time, active_time, recovery_time;
-	int clock_time, pio_mode, cycle_time;
-	u8 recovery_count2, cycle_count;
-	int setup_count, active_count, recovery_count;
-	int bus_speed = system_bus_clock();
-	ide_pio_data_t  d;
+	int setup_time, active_time, cycle_time;
+	u8  cycle_count, setup_count, active_count, recovery_count;
+	u8  pio_mode;
+	int clock_time = 1000 / system_bus_clock();
+	ide_pio_data_t pio;
 
-	pio_mode = ide_get_best_pio_mode(drive, mode_wanted, 5, &d);
-	cycle_time = d.cycle_time;
+	pio_mode = ide_get_best_pio_mode(drive, mode_wanted, 5, &pio);
+	cycle_time = pio.cycle_time;
 
-	/*
-	 * I copied all this complicated stuff from cmd640.c and made a few
-	 * minor changes.  For now I am just going to pray that it is correct.
-	 */
 	setup_time  = ide_pio_timings[pio_mode].setup_time;
 	active_time = ide_pio_timings[pio_mode].active_time;
-	recovery_time = cycle_time - (setup_time + active_time);
-	clock_time = 1000 / bus_speed;
-	cycle_count = (cycle_time + clock_time - 1) / clock_time;
-
-	setup_count = (setup_time + clock_time - 1) / clock_time;
 
-	active_count = (active_time + clock_time - 1) / clock_time;
+	setup_count  = quantize_timing( setup_time, clock_time);
+	cycle_count  = quantize_timing( cycle_time, clock_time);
+	active_count = quantize_timing(active_time, clock_time);
 
-	recovery_count = (recovery_time + clock_time - 1) / clock_time;
-	recovery_count2 = cycle_count - (setup_count + active_count);
-	if (recovery_count2 > recovery_count)
-		recovery_count = recovery_count2;
+	recovery_count = cycle_count - active_count;
+	/* program_drive_counts() takes care of zero recovery cycles */
 	if (recovery_count > 16) {
 		active_count += recovery_count - 16;
 		recovery_count = 16;
 	}
 	if (active_count > 16)
-		active_count = 16; /* maximum allowed by cmd646 */
+		active_count = 16; /* maximum allowed by cmd64x */
 
 	program_drive_counts (drive, setup_count, active_count, recovery_count);
 
 	cmdprintk("%s: PIO mode wanted %d, selected %d (%dns)%s, "
 		"clocks=%d/%d/%d\n",
 		drive->name, mode_wanted, pio_mode, cycle_time,
-		d.overridden ? " (overriding vendor mode)" : "",
+		pio.overridden ? " (overriding vendor mode)" : "",
 		setup_count, active_count, recovery_count);
 
 	return pio_mode;