Some drivers try to use a 64-bit dma_mask and a smaller (32-bit typically)
coherent dma mask.
We don't currently support that on platforms that do direct DMA
because:
- We use the generic dma_set_coherent_mask()
- It will use dma_supported() with the provided mask
- Our imlpementation of the latter in
dma_set_our dma_direct_dma_supported() will fail if the mask
passed isn't big enough to cover all of memory (+ DMA offset)
This fixes it by making dma_direct_dma_supported() use the ZONE_DMA32
limit when it's enabled, and removing the ifdef CONFIG_FSL_SOC around
the code in dma_direct_alloc_coherent() that supports allocating
from the 32-bit zone. (Nowadays, most drivers have been fixed).
This carries an additional change which is to generalize the test
against memblock_end_of_DRAM() + "dma_offset" to 32-bit platforms,
instead of just unconditionally returning 1 for these. This should
work since the rest of the code in the direct DMA ops assume this
is true anyway.
Signed-off-by: Benjamin Herrenschmidt <b...@kernel.crashing.org>
---
arch/powerpc/include/asm/pgtable.h | 1 +
arch/powerpc/kernel/dma.c | 21 ++++++---------------
arch/powerpc/mm/mem.c | 5 +++++
3 files changed, 12 insertions(+), 15 deletions(-)
diff --git a/arch/powerpc/include/asm/pgtable.h
b/arch/powerpc/include/asm/pgtable.h
index 9835ac4..a3680b8 100644
--- a/arch/powerpc/include/asm/pgtable.h
+++ b/arch/powerpc/include/asm/pgtable.h
@@ -217,6 +217,7 @@ extern pgd_t swapper_pg_dir[];
void limit_zone_pfn(enum zone_type zone, unsigned long max_pfn);
int dma_pfn_limit_to_zone(u64 pfn_limit);
+u64 dma_get_zone_limit(int zone);
extern void paging_init(void);
/*
diff --git a/arch/powerpc/kernel/dma.c b/arch/powerpc/kernel/dma.c
index 484b2d4..e24e0ae 100644
--- a/arch/powerpc/kernel/dma.c
+++ b/arch/powerpc/kernel/dma.c
@@ -53,16 +53,9 @@ void *dma_direct_alloc_coherent(struct device *dev, size_t
size,
#else
struct page *page;
int node = dev_to_node(dev);
-#ifdef CONFIG_FSL_SOC
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",
@@ -80,7 +73,6 @@ void *dma_direct_alloc_coherent(struct device *dev, size_t
size,
break;
#endif
};
-#endif /* CONFIG_FSL_SOC */
/* ignore region specifiers */
flag &= ~(__GFP_HIGHMEM);
@@ -149,14 +141,13 @@ 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 so platforms can set the limit in case
- * they have limited DMA windows
- */
- return mask >= get_dma_offset(dev) + (memblock_end_of_DRAM() - 1);
-#else
- return 1;
+ u64 offset = get_dma_offset(dev);
+ u64 limit = offset + memblock_end_of_DRAM() - 1;
+
+#if defined(CONFIG_ZONE_DMA32)
+ limit = offset + dma_get_zone_limit(ZONE_DMA32);
#endif
+ return mask >= limit;
}
static u64 dma_direct_get_required_mask(struct device *dev)
diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c
index f146ef0..a7f15e2 100644
--- a/arch/powerpc/mm/mem.c
+++ b/arch/powerpc/mm/mem.c
@@ -277,6 +277,11 @@ int dma_pfn_limit_to_zone(u64 pfn_limit)
return -EPERM;
}
+u64 dma_get_zone_limit(int zone)
+{
+ return max_zone_pfns[zone] << PAGE_SHIFT;
+}
+
/*
* paging_init() sets up the page tables - in fact we've already done this.
*/
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