ide-atapi: start DMA after issuing a packet command

upstream commit: 2eba08270990b99fb5429b76ee97184ddd272f7f

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>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>

diff --git a/drivers/ide/ide-atapi.c b/drivers/ide/ide-atapi.c
index 47497f8b4251e6d52c4a13b1d0e61503707b08bb..53a9e8dd4e071ac52c63b13b0a1154c2462e9efc 100644 (file)
--- a/drivers/ide/ide-atapi.c
+++ b/drivers/ide/ide-atapi.c
@@ -568,6 +568,10 @@ static ide_startstop_t ide_transfer_pc(ide_drive_t *drive)
                                             : ide_pc_intr),
                        timeout, expiry);
 
+       /* 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)
@@ -579,10 +583,6 @@ 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;
 }