ide: add "hdx=nodma" kernel parameter

* Add "hdx=nodma" option allowing user to disallow DMA for a given device.

* Obsolete "ide=nodma" option.
Acked-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>

Documentation/ide.txt

@@ -242,6 +242,8 @@ Summary of ide driver parameters for kernel command line
 			  and quite likely to cause trouble with
 			  older/odd IDE drives.
 
+ "hdx=nodma"		: disallow DMA
+
  "hdx=swapdata"		: when the drive is a disk, byte swap all data
 
  "hdx=bswap"		: same as above..........
@@ -286,8 +288,6 @@ Summary of ide driver parameters for kernel command line
 
  "ide=reverse"		: formerly called to pci sub-system, but now local.
 
- "ide=nodma"		: disable DMA globally for the IDE subsystem.
-
 The following are valid ONLY on ide0, which usually corresponds
 to the first ATA interface found on the particular host, and the defaults for
 the base,ctl ports must not be altered.

drivers/ide/ide-dma.c

@@ -759,7 +759,7 @@ static int ide_tune_dma(ide_drive_t *drive)
 {
 	u8 speed;
 
-	if (noautodma || (drive->id->capability & 1) == 0)
+	if (noautodma || drive->nodma || (drive->id->capability & 1) == 0)
 		return 0;
 
 	/* consult the list of known "bad" drives */

drivers/ide/ide.c

@@ -1272,7 +1272,7 @@ static int __init ide_setup(char *s)
 	if (!strcmp(s, "ide=nodma")) {
 		printk(" : Prevented DMA\n");
 		noautodma = 1;
-		return 1;
+		goto obsolete_option;
 	}
 
 #ifdef CONFIG_IDEPCI_PCIBUS_ORDER
@@ -1306,7 +1306,7 @@ static int __init ide_setup(char *s)
 	 */
 	if (s[0] == 'h' && s[1] == 'd' && s[2] >= 'a' && s[2] <= max_drive) {
 		const char *hd_words[] = {
-			"none", "noprobe", "nowerr", "cdrom", "minus5",
+			"none", "noprobe", "nowerr", "cdrom", "nodma",
 			"autotune", "noautotune", "minus8", "swapdata", "bswap",
 			"noflush", "remap", "remap63", "scsi", NULL };
 		unit = s[2] - 'a';
@@ -1334,6 +1334,9 @@ static int __init ide_setup(char *s)
 				drive->ready_stat = 0;
 				hwif->noprobe = 0;
 				goto done;
+			case -5: /* nodma */
+				drive->nodma = 1;
+				goto done;
 			case -6: /* "autotune" */
 				drive->autotune = IDE_TUNE_AUTO;
 				goto obsolete_option;

include/linux/ide.h

@@ -599,6 +599,7 @@ typedef struct ide_drive_s {
 	unsigned nice0		: 1;	/* give obvious excess bandwidth */
 	unsigned nice2		: 1;	/* give a share in our own bandwidth */
 	unsigned doorlocking	: 1;	/* for removable only: door lock/unlock works */
+	unsigned nodma		: 1;	/* disallow DMA */
 	unsigned autotune	: 2;	/* 0=default, 1=autotune, 2=noautotune */
 	unsigned remap_0_to_1	: 1;	/* 0=noremap, 1=remap 0->1 (for EZDrive) */
 	unsigned blocked        : 1;	/* 1=powermanagment told us not to do anything, so sleep nicely */