Re: 2.1.110 and newer, SB AWE64

Thomas Sailer (sailer@ife.ee.ethz.ch)
Mon, 07 Sep 1998 14:26:36 +0200


MOLNAR Ingo wrote:

> hm, if DMA channels are being mucked with from within an IRQ handler, then
> we should spinlock the DMA controller itself. It's only in recent kernels

I've thought about this too. Yes, sound among others need to get the
residue count out of the DMA controller at interrupt time. The problem
with the 8237 design is the "intrinsic" state shared between all the
channels on a particular chip, especially the "byte pointer flip flop".
This FF is affected whenever one reads or writes values, be it base
address or counter values.

So yes, the cleanest thing would be a global spinlock for the DMA
controller.

> the clean solution IMO is to add a global spinlock to DMA controllers.

Tom

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.rutgers.edu
Please read the FAQ at http://www.tux.org/lkml/faq.html