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>
diff --git a/drivers/ide/ide-taskfile.c b/drivers/ide/ide-taskfile.c
index c58edc8..3ecafab 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 @@
/* 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