From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Pierre Ossman <drzeus-list@drzeus.cx>
Cc: LKML <linux-kernel@vger.kernel.org>
Subject: Re: ISA DMA controller hangs
Date: Sat, 28 May 2005 14:51:26 +0100 [thread overview]
Message-ID: <1117288285.2685.10.camel@localhost.localdomain> (raw)
In-Reply-To: <42987450.9000601@drzeus.cx>
On Sad, 2005-05-28 at 14:38, Pierre Ossman wrote:
> I've been having some problems with ISA DMA transfers failing. They work
> fine until the machine does a suspend-to-ram. After that all DMA
> transfers stall. Does perhaps the DMA controller need a kick in the ***
> after a suspend? I'm no expert on the ISA DMA controller so I could use
> some help here.
The DMA controller has some bits of state which are potentially in need
of restoration as well as a need to ensure you don't suspend while it is
running I would imagine. Even for bus masters I believe you would need
to restore the DMA enable bits.
See include/asm-i386/dma.h but note that some registers have side
effects and the dma_outb etc are used to get required delays on some PCs
Alan
next prev parent reply other threads:[~2005-05-28 13:53 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-05-28 13:38 ISA DMA controller hangs Pierre Ossman
2005-05-28 13:51 ` Alan Cox [this message]
2005-06-05 8:21 ` Pierre Ossman
2005-06-05 14:03 ` Pierre Ossman
2005-06-16 15:53 ` Pierre Ossman
2005-06-16 16:06 ` Russell King
2005-06-18 8:15 ` Pierre Ossman
2005-06-19 15:45 ` Russell King
2005-06-30 8:00 ` Pierre Ossman
2005-06-30 11:28 ` Alan Cox
2005-06-30 12:20 ` Pierre Ossman
2005-06-30 17:55 ` [PATCH 1/2] ISA DMA suspend for i386 Pierre Ossman
2005-06-30 17:58 ` [PATCH 2/2] ISA DMA suspend for x86_64 Pierre Ossman
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