[PATCH RFC 51/51] ARM: 7805/1: mm: change max*pfn to include the physical offset of memory

Santosh Shilimkar
2013-08-01T22:25:46Z

Most of the kernel code assumes that max*pfn is maximum pfns because
the physical start of memory is expected to be PFN0. Since this
assumption is not true on ARM architectures, the meaning of max*pfn
is number of memory pages. This is done to keep drivers happy which
are making use of of these variable to calculate the dma bounce limit
using dma_mask.

Now since we have a architecture override possibility for DMAable
maximum pfns, lets make meaning of max*pfns as maximum pnfs on ARM
as well.

Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
---
arch/arm/include/asm/dma-mapping.h | 8 ++++++++
arch/arm/mm/init.c | 10 ++++------
2 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/arch/arm/include/asm/dma-mapping.h b/arch/arm/include/asm/dma-mapping.h
index 5b579b9..863cd84 100644
--- a/arch/arm/include/asm/dma-mapping.h
+++ b/arch/arm/include/asm/dma-mapping.h
@@ -64,6 +64,7 @@ static inline dma_addr_t virt_to_dma(struct device *dev, void *addr)
{
return (dma_addr_t)__virt_to_bus((unsigned long)(addr));
}
+
#else
static inline dma_addr_t pfn_to_dma(struct device *dev, unsigned long pfn)
{
@@ -86,6 +87,13 @@ static inline dma_addr_t virt_to_dma(struct device *dev, void *addr)
}
#endif

+/* The ARM override for dma_max_pfn() */
+static inline unsigned long dma_max_pfn(struct device *dev)
+{
+ return PHYS_PFN_OFFSET + dma_to_pfn(dev, *dev->dma_mask);
+}
+#define dma_max_pfn(dev) dma_max_pfn(dev)
+
/*
* DMA errors are defined by all-bits-set in the DMA address.
*/
diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c
index b5b5836..2731dcf 100644
--- a/arch/arm/mm/init.c
+++ b/arch/arm/mm/init.c
@@ -422,12 +422,10 @@ void __init bootmem_init(void)
* This doesn't seem to be used by the Linux memory manager any
* more, but is used by ll_rw_block. If we can get rid of it, we
* also get rid of some of the stuff above as well.
- *
- * Note: max_low_pfn and max_pfn reflect the number of _pages_ in
- * the system, not the maximum PFN.
*/
- max_low_pfn = max_low - PHYS_PFN_OFFSET;
- max_pfn = max_high - PHYS_PFN_OFFSET;
+ min_low_pfn = min;
+ max_low_pfn = max_low;
+ max_pfn = max_high;
}

/*
@@ -533,7 +531,7 @@ static inline void free_area_high(unsigned long pfn, unsigned long end)
static void __init free_highpages(void)
{
#ifdef CONFIG_HIGHMEM
- unsigned long max_low = max_low_pfn + PHYS_PFN_OFFSET;
+ unsigned long max_low = max_low_pfn;
struct memblock_region *mem, *res;

/* set highmem page free */
--
1.7.4.4