[PATCH] ide: Allow IDE interface to specify its not capable of 32-bit operations

In some embedded systems the IDE hardware interface may only support 16-bit
or smaller accesses.  Allow the interface to specify if this is the case
and don't allow the drive or user to override the setting.
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
Acked-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

drivers/ide/ide-disk.c

@@ -978,8 +978,6 @@ static void idedisk_setup (ide_drive_t *drive)
 		ide_dma_verbose(drive);
 	printk("\n");
 
-	drive->no_io_32bit = id->dword_io ? 1 : 0;
-
 	/* write cache enabled? */
 	if ((id->csfo & 1) || (id->cfs_enable_1 & (1 << 5)))
 		drive->wcache = 1;

drivers/ide/ide-probe.c

@@ -858,6 +858,15 @@ static void probe_hwif(ide_hwif_t *hwif)
 			}
 		}
 	}
+
+	for (unit = 0; unit < MAX_DRIVES; ++unit) {
+		ide_drive_t *drive = &hwif->drives[unit];
+
+		if (hwif->no_io_32bit)
+			drive->no_io_32bit = 1;
+		else
+			drive->no_io_32bit = drive->id->dword_io ? 1 : 0;
+	}
 }
 
 static int hwif_init(ide_hwif_t *hwif);

include/linux/ide.h

@@ -792,6 +792,7 @@ typedef struct hwif_s {
 	unsigned	no_dsc     : 1;	/* 0 default, 1 dsc_overlap disabled */
 	unsigned	auto_poll  : 1; /* supports nop auto-poll */
 	unsigned	sg_mapped  : 1;	/* sg_table and sg_nents are ready */
+	unsigned	no_io_32bit : 1; /* 1 = can not do 32-bit IO ops */
 
 	struct device	gendev;
 	struct completion gendev_rel_comp; /* To deal with device release() */