[PATCH v2] powerpc: Only do dynamic DMA zone limits on platforms that need it

Michael Ellerman mpe at ellerman.id.au
Thu Oct 16 17:47:48 AEDT 2014

Scott's patch 1c98025c6c95 "Dynamic DMA zone limits" changed
dma_direct_alloc_coherent() to start using dev->coherent_dma_mask.

That seems fair enough, but it exposes the fact that some of the drivers
we care about on IBM platforms aren't setting the coherent mask.

The proper fix is to have drivers set the coherent mask and also have
the platform code honor it.

For now, just restrict the dynamic DMA zone limits to the platforms that
need it.

Signed-off-by: Michael Ellerman <mpe at ellerman.id.au>
 arch/powerpc/kernel/dma.c | 8 ++++++++
 1 file changed, 8 insertions(+)

v2: Use FSL_SOC.

diff --git a/arch/powerpc/kernel/dma.c b/arch/powerpc/kernel/dma.c
index adac9dc54aee..484b2d4462c1 100644
--- a/arch/powerpc/kernel/dma.c
+++ b/arch/powerpc/kernel/dma.c
@@ -53,9 +53,16 @@ void *dma_direct_alloc_coherent(struct device *dev, size_t size,
 	struct page *page;
 	int node = dev_to_node(dev);
 	u64 pfn = get_pfn_limit(dev);
 	int zone;
+	/*
+	 * This code should be OK on other platforms, but we have drivers that
+	 * don't set coherent_dma_mask. As a workaround we just ifdef it. This
+	 * whole routine needs some serious cleanup.
+	 */
 	zone = dma_pfn_limit_to_zone(pfn);
 	if (zone < 0) {
 		dev_err(dev, "%s: No suitable zone for pfn %#llx\n",
@@ -73,6 +80,7 @@ void *dma_direct_alloc_coherent(struct device *dev, size_t size,
+#endif /* CONFIG_FSL_SOC */
 	/* ignore region specifiers */
 	flag  &= ~(__GFP_HIGHMEM);

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