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

From: Russell King <[email-masked]>
Date: Fri, 20 Sep 2013 00:44:07 +0100

From: Santosh Shilimkar <[email-masked]>

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 <[email-masked]>
Signed-off-by: Russell King <[email-masked]>
---
 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 8aab24f..d50533c 100644
--- a/arch/arm/mm/init.c
+++ b/arch/arm/mm/init.c
@@ -426,12 +426,10 @@ 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;
 }
 
 /*
@@ -537,7 +535,7 @@ 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