ARM: Qualify enabling of swiotlb_init()

commit 536feceb27ca41c352bb3c8396b92c4ec22ae3e1 upstream.

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: bc856c0eca9d ("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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c
index 0804a6af4a3b7103c729a48d12d898212ecbc0ff..5a3641b5ec2cd09e5638dfbcd07c7ae8823e769c 100644 (file)
--- a/arch/arm/mm/init.c
+++ b/arch/arm/mm/init.c
@@ -469,7 +469,11 @@ 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);