On Fri, 2009-07-31 at 20:41 +0100, David Woodhouse wrote:
> On an iMac G5, the b43 driver is failing to initialise because trying to
> set the dma mask to 30-bit fails. Even though there's only 512MiB of RAM
> in the machine anyway:
> https://bugzilla.redhat.com/show_bug.cgi?id=514787
>
> We should probably let it succeed if the available RAM in the system
> doesn't exceed the requested limit.
I've slightly modified the patch to use lmb_end_of_DRAM() instead
of highest_memmap_pfn because the later is an mm internal.h thing,
it looked too fishy to rely on it form arch code with a local
"extern" in the C code :-) It's not going to cause much more overhead
and it's not a hot path anyway afaik.
Below is a copy of what I've commited to my merge branch and will
ask Linus to pull in a few minutes.
>From 10ba96df690618632a8786494b2359f5ee350048 Mon Sep 17 00:00:00 2001
From: David Woodhouse <dw...@infradead.org>
Date: Fri, 31 Jul 2009 09:41:50 +0000
Subject: [PATCH] powerpc/dma: pci_set_dma_mask() shouldn't fail if mask fits in
RAM
On an iMac G5, the b43 driver is failing to initialise because trying to
set the dma mask to 30-bit fails. Even though there's only 512MiB of RAM
in the machine anyway:
https://bugzilla.redhat.com/show_bug.cgi?id=514787
We should probably let it succeed if the available RAM in the system
doesn't exceed the requested limit.
Signed-off-by: David Woodhouse <david.woodho...@intel.com>
Signed-off-by: Benjamin Herrenschmidt <b...@kernel.crashing.org>
---
arch/powerpc/kernel/dma.c | 6 +++---
1 files changed, 3 insertions(+), 3 deletions(-)
diff --git a/arch/powerpc/kernel/dma.c b/arch/powerpc/kernel/dma.c
index 20a60d6..ccf129d 100644
--- a/arch/powerpc/kernel/dma.c
+++ b/arch/powerpc/kernel/dma.c
@@ -7,6 +7,7 @@
#include <linux/device.h>
#include <linux/dma-mapping.h>
+#include <linux/lmb.h>
#include <asm/bug.h>
#include <asm/abs_addr.h>
@@ -90,11 +91,10 @@ static void dma_direct_unmap_sg(struct device *dev, struct
scatterlist *sg,
static int dma_direct_dma_supported(struct device *dev, u64 mask)
{
#ifdef CONFIG_PPC64
- /* Could be improved to check for memory though it better be
- * done via some global so platforms can set the limit in case
+ /* Could be improved so platforms can set the limit in case
* they have limited DMA windows
*/
- return mask >= DMA_BIT_MASK(32);
+ return mask >= (lmb_end_of_DRAM() - 1);
#else
return 1;
#endif
--
1.6.1.2.14.gf26b5
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