ide-atapi: start DMA after issuing a packet command

Apparently¹, some ATAPI devices want to see the packet command first
before enabling DMA otherwise they simply hang indefinitely. Reorder the
two steps and start DMA only after having issued the command first.

[1] http://marc.info/?l=linux-kernel&m=123835520317235&w=2

Signed-off-by: Borislav Petkov <petkovbb@gmail.com>
Reported-by: Michael Roth <mroth@nessie.de>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>

diff --git a/drivers/ide/ide-atapi.c b/drivers/ide/ide-atapi.c
index d937e45a6777c2e015055ce6e4b30393d59d502b..f591166d2c9335739de34748d688e82880d476e1 100644 (file)
--- a/drivers/ide/ide-atapi.c
+++ b/drivers/ide/ide-atapi.c
@@ -613,6 +613,10 @@ static ide_startstop_t ide_transfer_pc(ide_drive_t *drive)
                                             : ide_pc_intr),
                        timeout);
 
+       /* Send the actual packet */
+       if ((drive->atapi_flags & IDE_AFLAG_ZIP_DRIVE) == 0)
+               hwif->tp_ops->output_data(drive, NULL, rq->cmd, cmd_len);
+
        /* Begin DMA, if necessary */
        if (dev_is_idecd(drive)) {
                if (drive->dma)
@@ -624,10 +628,6 @@ static ide_startstop_t ide_transfer_pc(ide_drive_t *drive)
                }
        }
 
-       /* Send the actual packet */
-       if ((drive->atapi_flags & IDE_AFLAG_ZIP_DRIVE) == 0)
-               hwif->tp_ops->output_data(drive, NULL, rq->cmd, cmd_len);
-
        return ide_started;
 }