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drm/radeon/kms: fix for radeon on systems >4GB without hardware iommu 

On my x86_64 system with >4GB of ram and swiotlb instead of
a hardware iommu (because I have a VIA chipset), the call
to pci_set_dma_mask (see below) with 40bits returns an error.

But it seems that the radeon driver is designed to have
need_dma32 = true exactly if pci_set_dma_mask is called
with 32 bits and false if it is called with 40 bits.

I have read somewhere that the default are 32 bits. So if the
call fails I suppose that need_dma32 should be set to true.

And indeed the patch fixes the problem I have had before
and which I had described here:
http://choon.net/forum/read.php?21,106131,115940

Acked-by: Alex Deucher <alexdeucher@gmail.com>
cc: stable@kernel.org
Signed-off-by: Dave Airlie <airlied@redhat.com>
This commit is contained in:
Daniel Haid 2011-06-08 20:04:45 +10:00 committed by Dave Airlie
parent 428c6e3630
commit 62fff811d7
1 changed files with 1 additions and 0 deletions
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1
drivers/gpu/drm/radeon/radeon_device.c
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@ -754,6 +754,7 @@ int radeon_device_init(struct radeon_device *rdev,
dma_bits = rdev->need_dma32 ? 32 : 40;
r = pci_set_dma_mask(rdev->pdev, DMA_BIT_MASK(dma_bits));
if (r) {
rdev->need_dma32 = true;
printk(KERN_WARNING "radeon: No suitable DMA available.\n");
}