Commit 9bd27cba authored Nov 02, 2008 by Borislav Petkov Committed by Bartlomiej Zolnierkiewicz Nov 02, 2008

ide-cd: fix DMA alignment regression

e5318b53 ("ide: use the dma safe check for
REQ_TYPE_ATA_PC") introduced a regression which caused some ATAPI drives to
turn off DMA for REQ_TYPE_BLOCK_PC commands while burning and thus degrading
performance and ultimately causing an excessive amount of underruns.

The issue is documented also in:
http://bugzilla.kernel.org/show_bug.cgi?id=11742

.

Signed-off-by: Borislav Petkov <petkovbb@gmail.com>
Cc: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Tested-by: Valerio Passini <valerio.passini@unicam.it>
[bart: fixup patch description per comments from Sergei Shtylyov]
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>

parent 721d5dfe

drivers/ide/ide-cd.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -1250,7 +1250,8 @@ static void cdrom_do_block_pc(ide_drive_t drive, struct request rq)
		* separate masks.
		*/
		alignment = queue_dma_alignment(q) \| q->dma_pad_mask;
		if ((unsigned long)buf & alignment \|\| rq->data_len & alignment
		if ((unsigned long)buf & alignment
		\|\| rq->data_len & q->dma_pad_mask
		\|\| object_is_on_stack(buf))
		drive->dma = 0;
		}

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