ARM: Qualify enabling of swiotlb_init()

We do not need a SWIOTLB unless we have DRAM that is addressable beyond
the arm_dma_limit. Compare max_pfn with arm_dma_pfn_limit to determine
whether we do need a SWIOTLB to be initialized.

Fixes: ad3c7b18c5b3 ("arm: use swiotlb for bounce buffering on LPAE configs")
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c
index 828a256..8356bf1 100644 (file)
--- a/arch/arm/mm/init.c
+++ b/arch/arm/mm/init.c
@@ -301,7 +301,11 @@ static void __init free_highpages(void)
 void __init mem_init(void)
 {
 #ifdef CONFIG_ARM_LPAE
-       swiotlb_init(1);
+       if (swiotlb_force == SWIOTLB_FORCE ||
+           max_pfn > arm_dma_pfn_limit)
+               swiotlb_init(1);
+       else
+               swiotlb_force = SWIOTLB_NO_FORCE;
 #endif
 
        set_max_mapnr(pfn_to_page(max_pfn) - mem_map);