Re: [PATCH 0/4] allow drivers to flush in-flight DMA v2

[David Miller <davem@davemloft.net>]

From: akepner@sgi.com
Date: Thu, 27 Sep 2007 18:09:26 -0700

> 
> On Altix, DMA may be reordered between a device and host memory. 
> This reordering can happen in the NUMA interconnect, and it usually 
> results in correct operation and improved performance. In some 
> situations it may be necessary to explicitly synchronize DMA from 
> the device.
> 
> This patchset allows a memory region to be mapped with a "dmabarrier". 
> Writes to the memory region will cause in-flight DMA to be flushed, 
> providing a mechanism to order DMA from a device.

My only beef with this patch set is that it seems
a bit much to create a totally new function name every
time we want to set some kind of new attribute on some
DMA object.  Why not add a "dma_set_flags()" or similar
that can be used later on to set other kinds of aspects
we'd like to change?

You can make the arguments "u32 flags" and "int dir".
Actually you should probably use the dma direction
enumaration instead of 'int'.