[patch 028/100] ide-atapi: start DMA after issuing a packet command

Chris Wright
2009-04-23T07:36:09Z

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-stable review patch. If anyone has any objections, please let us know.
---------------------

From: Borislav Petkov <petkovbb@gmail.com>

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>
---
drivers/ide/ide-atapi.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

--- a/drivers/ide/ide-atapi.c
+++ b/drivers/ide/ide-atapi.c
@@ -568,6 +568,10 @@ static ide_startstop_t ide_transfer_pc(i
: 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(i
}
}

- /* 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;
}