tx4939ide: Do not use zero count PRD entry

This fixes data corruption on some heavy load.

Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Cc: stable <stable@kernel.org>
Cc: sshtylyov@ru.mvista.com
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/drivers/ide/tx4939ide.c b/drivers/ide/tx4939ide.c
index bafb7d1a22e2..30d0d256230f 100644
--- a/drivers/ide/tx4939ide.c
+++ b/drivers/ide/tx4939ide.c
@@ -259,6 +259,12 @@ static int tx4939ide_build_dmatable(ide_drive_t *drive, struct request *rq)
                         bcount = 0x10000 - (cur_addr & 0xffff);
                         if (bcount > cur_len)
                                 bcount = cur_len;
+                        /*
+                         * This workaround for zero count seems required.
+                         * (standard ide_build_dmatable do it too)
+                         */
+                        if ((bcount & 0xffff) == 0x0000)
+                                bcount = 0x8000;
                         *table++ = bcount & 0xffff;
                         *table++ = cur_addr;
                         cur_addr += bcount;