Re: [PATCH 22/40] ide-floppy: start DMA engine in idefloppy_transfer_pc1()

From: Sergei Shtylyov
Date: Tue May 20 2008 - 07:01:20 EST


Bartlomiej Zolnierkiewicz wrote:

Start DMA engine and set PC_FLAG_DMA_IN_PROGRESS flag in
idefloppy_transfer_pc1() instead of idefloppy_issue_pc()

Good. I have long ago noticed that DMA is started too early in ide-floppy which is known to cobfuse some chips (like PDC20246) and was going to do a patch at first but the lack of hardware (and time) stopped me...

so the Status Register and the Interrupt Reason Register
are checked first.

Cc: Borislav Petkov <petkovbb@xxxxxxxxx>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@xxxxxxxxx>

Index: b/drivers/ide/ide-floppy.c
--- a/drivers/ide/ide-floppy.c
+++ b/drivers/ide/ide-floppy.c
@@ -568,6 +569,12 @@ static ide_startstop_t idefloppy_transfe
ide_set_handler(drive, &idefloppy_pc_intr, timeout, expiry);
+ /* Begin DMA, if necessary */
+ if (pc->flags & PC_FLAG_DMA_OK) {
+ pc->flags |= PC_FLAG_DMA_IN_PROGRESS;
+ hwif->dma_ops->dma_start(drive);
+ }

May be too early still... ide-cd does this after writing the command packet.

WBR, Sergei
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