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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>
This commit is contained in:
Bartlomiej Zolnierkiewicz 2008-01-26 20:13:09 +01:00
parent 3a5015cc9d
commit 9e47be0c97
5 changed files with 3 additions and 41 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
Documentation/ide.txt
View File

@ -244,10 +244,6 @@ Summary of ide driver parameters for kernel command line
"hdx=nodma" : disallow DMA
"hdx=swapdata" : when the drive is a disk, byte swap all data
"hdx=bswap" : same as above..........
"hdx=scsi" : the return of the ide-scsi flag, this is useful for
allowing ide-floppy, ide-tape, and ide-cdrom|writers
to use ide-scsi emulation on a device specific option.

1
drivers/ide/ide-disk.c
View File

@ -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);

32
drivers/ide/ide-taskfile.c
View File

@ -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

6
drivers/ide/ide.c
View File

@ -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;

1
include/linux/ide.h
View File

@ -394,7 +394,6 @@ typedef struct ide_drive_s {
u8 state; /* retry state */
u8 waiting_for_dma; /* dma currently in progress */
u8 unmask; /* okay to unmask other irqs */
u8 bswap; /* byte swap data */
u8 noflush; /* don't attempt flushes */
u8 dsc_overlap; /* DSC overlap */
u8 nice1; /* give potential excess bandwidth */