[ath9k-devel] [RFC] ath9k: Insert wmb before linking dma descriptors

[John W. Linville <linville@tuxdriver.com>]

On Mon, Oct 04, 2010 at 10:55:08PM +0200, Bj?rn Smedman wrote:
> Hi all,
> 
> I've been looking at how ath9k does DMA and comparing with the
> recommendations in the Linux kernel documentation for the DMA API[1]. To
> me it looks like we risk setting up incorrect DMA descriptors on
> platforms that can reorder writes because all data in the descriptor may
> not be written to memory before the descriptor is linked into the DMA
> chain.
> 
> The patch below attempts to remove this risk by inserting a write memory
> barrier between where we set up a descriptor and where we add it to the 
> DMA chain. My hope is that this may solve some of the harder chip lockups 
> on MIPS but more testing is required to determine if it has this effect.
> 
> Any thoughts?
> 
> /Bj?rn
> 
> 1. http://www.mjmwired.net/kernel/Documentation/DMA-API.txt

I think this seems OK...?

John
-- 
John W. Linville		Someday the world will need a hero, and you
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