linux-kernel - scatterlist.c or dma_map

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Message-ID: <c384c5ea0809280847p6a7d2e9as1b2454142751a468@mail.gmail.com>
Date:	Sun, 28 Sep 2008 17:47:59 +0200
From:	"Leon Woestenberg" <leon.woestenberg@...il.com>
To:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: scatterlist.c or dma_map_sg() should coalesce?

Hello,

in 2.6.27+, if I want to create a scatterlist of a large buffer in
virtual memory in a device driver, can I expect the scatterlist and/or
mapping API to provide me with a minimal list, each entry describing a
maximum bus-contiguous piece of memory? (i.e. can I assume coalescing
is done for me?).

In 2.6.24, dma_map_sg() *may* coalesce, but doesn't do so for my
platform, so for optimal DMA transfers the device driver needs to
coalesce the list entries.

Regards,
-- 
Leon
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