From: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Date: Wed, 24 Sep 2008 11:48:37 +0000 (+0900)
Subject: x86: restore old GART alloc_coherent behavior
X-Git-Tag: v2.6.28-rc1~712^2^4~7
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=1d990882153f36723f9e8717c4401689e64c7a36;p=pandora-kernel.git

x86: restore old GART alloc_coherent behavior

Currently, GART alloc_coherent tries to allocate pages with GFP_DMA32
for a device having dma_masks > 24bit < 32bits. If GART gets an
address that a device can't access to, GART try to map the address to
a virtual I/O address that the device can access to.

But Andi pointed out, "The GART is somewhere in the 4GB range so you
cannot use it to map anything < 4GB. Also GART is pretty small."

http://lkml.org/lkml/2008/9/12/43

That is, it's possible that GART doesn't have virtual I/O address
space that a device can access to. The above behavior doesn't work for
a device having dma_masks > 24bit < 32bits.

This patch restores old GART alloc_coherent behavior (before the
alloc_coherent rewrite).

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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