ide: ide_get_best_pio_mode() returns incorrect IORDY setting (take 2)

The function ide_get_best_pio_mode() fails to return the correct IORDY setting
for the explicitly specified modes -- fix this along with the heading comment,
and also remove the long commented out code.

Also, while at it, correct the misliading comment about the PIO cycle time in
<linux/ide.h> -- it actually consists of only the active and recovery periods,
with only some chips also including the address setup time into equation...

[ bart: sl82c105 seems to be currently the only driver affected by this fix ]
Signed-off-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>

drivers/ide/ide-lib.c

@@ -345,16 +345,16 @@ static int ide_scan_pio_blacklist (char *model)
 
 /**
  *	ide_get_best_pio_mode	-	get PIO mode from drive
- *	@driver: drive to consider
+ *	@drive: drive to consider
  *	@mode_wanted: preferred mode
- *	@max_mode: highest allowed
- *	@d: pio data
+ *	@max_mode: highest allowed mode
+ *	@d: PIO data
  *
  *	This routine returns the recommended PIO settings for a given drive,
  *	based on the drive->id information and the ide_pio_blacklist[].
- *	This is used by most chipset support modules when "auto-tuning".
  *
- *	Drive PIO mode auto selection
+ *	Drive PIO mode is auto-selected if 255 is passed as mode_wanted.
+ *	This is used by most chipset support modules when "auto-tuning".
  */
 
 u8 ide_get_best_pio_mode (ide_drive_t *drive, u8 mode_wanted, u8 max_mode, ide_pio_data_t *d)
@@ -367,6 +367,7 @@ u8 ide_get_best_pio_mode (ide_drive_t *drive, u8 mode_wanted, u8 max_mode, ide_p
 
 	if (mode_wanted != 255) {
 		pio_mode = mode_wanted;
+		use_iordy = (pio_mode > 2);
 	} else if (!drive->id) {
 		pio_mode = 0;
 	} else if ((pio_mode = ide_scan_pio_blacklist(id->model)) != -1) {
@@ -396,19 +397,12 @@ u8 ide_get_best_pio_mode (ide_drive_t *drive, u8 mode_wanted, u8 max_mode, ide_p
 			}
 		}
 
-#if 0
-		if (drive->id->major_rev_num & 0x0004) printk("ATA-2 ");
-#endif
-
 		/*
 		 * Conservative "downgrade" for all pre-ATA2 drives
 		 */
 		if (pio_mode && pio_mode < 4) {
 			pio_mode--;
 			overridden = 1;
-#if 0
-			use_iordy = (pio_mode > 2);
-#endif
 			if (cycle_time && cycle_time < ide_pio_timings[pio_mode].cycle_time)
 				cycle_time = 0; /* use standard timing */
 		}

include/linux/ide.h

@@ -1359,7 +1359,8 @@ u8 ide_dump_status(ide_drive_t *, const char *, u8);
 typedef struct ide_pio_timings_s {
 	int	setup_time;	/* Address setup (ns) minimum */
 	int	active_time;	/* Active pulse (ns) minimum */
-	int	cycle_time;	/* Cycle time (ns) minimum = (setup + active + recovery) */
+	int	cycle_time;	/* Cycle time (ns) minimum = */
+				/* active + recovery (+ setup for some chips) */
 } ide_pio_timings_t;
 
 typedef struct ide_pio_data_s {