ide: remove broken disk byte-swapping support

Remove broken disk byte-swapping support:
- it can cause a data corruption on SMP (or if using PREEMPT on UP)
- all data coming from disk are byte-swapped by taskfile_*_data() which
  results in incorrect identify data being reported by /proc/ide/ and IOCTLs
- "hdx=bswap/byteswap" kernel parameter has been broken on m68k host drivers
  (including Atari/Q40 ones) since 2.5.x days (because of 'hwif' zero-ing)
- byte-swapping is limited to PIO transfers (for working with TiVo disks on
  x86 machines using user-space solutions or dm-byteswap should result in
  much better performance because DMA can be used)

For previous discussions please see:

http://www.ussg.iu.edu/hypermail/linux/kernel/0201.0/0768.html
http://lkml.org/lkml/2004/2/28/111

[ I have dm-byteswap device mapper target if somebody is interested
  (patch is for 2.6.4 though but I'll dust it off if needed). ]

Acked-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>

3 files changed, 3 insertions, 36 deletions

diff --git a/drivers/ide/ide-disk.c b/drivers/ide/ide-disk.c
index c1fb75c387ea..041be43a62cb 100644
--- a/drivers/ide/ide-disk.c
+++ b/drivers/ide/ide-disk.c
@@ -761,7 +761,6 @@ static void idedisk_add_settings(ide_drive_t *drive)
         ide_add_setting(drive,  "bios_head",    SETTING_RW,     TYPE_BYTE,      0,      255,                    1,      1,      &drive->bios_head,      NULL);
         ide_add_setting(drive,  "bios_sect",    SETTING_RW,     TYPE_BYTE,      0,      63,                     1,      1,      &drive->bios_sect,      NULL);
         ide_add_setting(drive,  "address",      SETTING_RW,     TYPE_BYTE,      0,      2,                      1,      1,      &drive->addressing,     set_lba_addressing);
-        ide_add_setting(drive,  "bswap",        SETTING_READ,   TYPE_BYTE,      0,      1,                      1,      1,      &drive->bswap,          NULL);
         ide_add_setting(drive,  "multcount",    SETTING_RW,     TYPE_BYTE,      0,      id->max_multsect,       1,      1,      &drive->mult_count,     set_multcount);
         ide_add_setting(drive,  "nowerr",       SETTING_RW,     TYPE_BYTE,      0,      1,                      1,      1,      &drive->nowerr,         set_nowerr);
         ide_add_setting(drive,  "lun",          SETTING_RW,     TYPE_INT,       0,      7,                      1,      1,      &drive->lun,            NULL);
diff --git a/drivers/ide/ide-taskfile.c b/drivers/ide/ide-taskfile.c
index c58edc86ed3e..3ecafab8f54e 100644
--- a/drivers/ide/ide-taskfile.c
+++ b/drivers/ide/ide-taskfile.c
@@ -35,34 +35,6 @@
 #include <asm/uaccess.h>
 #include <asm/io.h>
 
-static void ata_bswap_data (void *buffer, int wcount)
-{
-        u16 *p = buffer;
-
-        while (wcount--) {
-                *p = *p << 8 | *p >> 8; p++;
-                *p = *p << 8 | *p >> 8; p++;
-        }
-}
-
-static void taskfile_input_data(ide_drive_t *drive, void *buffer, u32 wcount)
-{
-        HWIF(drive)->ata_input_data(drive, buffer, wcount);
-        if (drive->bswap)
-                ata_bswap_data(buffer, wcount);
-}
-
-static void taskfile_output_data(ide_drive_t *drive, void *buffer, u32 wcount)
-{
-        if (drive->bswap) {
-                ata_bswap_data(buffer, wcount);
-                HWIF(drive)->ata_output_data(drive, buffer, wcount);
-                ata_bswap_data(buffer, wcount);
-        } else {
-                HWIF(drive)->ata_output_data(drive, buffer, wcount);
-        }
-}
-
 void ide_tf_load(ide_drive_t *drive, ide_task_t *task)
 {
         ide_hwif_t *hwif = drive->hwif;
@@ -352,9 +324,9 @@ static void ide_pio_sector(ide_drive_t *drive, unsigned int write)
 
         /* do the actual data transfer */
         if (write)
-                taskfile_output_data(drive, buf, SECTOR_WORDS);
+                hwif->ata_output_data(drive, buf, SECTOR_WORDS);
         else
-                taskfile_input_data(drive, buf, SECTOR_WORDS);
+                hwif->ata_input_data(drive, buf, SECTOR_WORDS);
 
         kunmap_atomic(buf, KM_BIO_SRC_IRQ);
 #ifdef CONFIG_HIGHMEM
diff --git a/drivers/ide/ide.c b/drivers/ide/ide.c
index 5f3e53ec5838..52115ef1f01a 100644
--- a/drivers/ide/ide.c
+++ b/drivers/ide/ide.c
@@ -1303,7 +1303,7 @@ 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", "nodma",
-                        "autotune", "noautotune", "minus8", "swapdata", "bswap",
+                        "autotune", "noautotune", "-8", "-9", "-10",
                         "noflush", "remap", "remap63", "scsi", NULL };
                 unit = s[2] - 'a';
                 hw   = unit / MAX_DRIVES;
@@ -1339,10 +1339,6 @@ static int __init ide_setup(char *s)
                         case -7: /* "noautotune" */
                                 drive->autotune = IDE_TUNE_NOAUTO;
                                 goto obsolete_option;
-                        case -9: /* "swapdata" */
-                        case -10: /* "bswap" */
-                                drive->bswap = 1;
-                                goto done;
                         case -11: /* noflush */
                                 drive->noflush = 1;
                                 goto done;