[PATCH stable 5.10] ARM: Qualify enabling of swiotlb_init()

From: Florian Fainelli
Date: Wed Sep 22 2021 - 20:14:36 EST


commit fcf044891c84e38fc90eb736b818781bccf94e38 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: ad3c7b18c5b3 ("arm: use swiotlb for bounce buffering on LPAE configs")
Signed-off-by: Florian Fainelli <f.fainelli@xxxxxxxxx>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
---
arch/arm/mm/init.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c
index d54d69cf1732..75f3ab531bdf 100644
--- a/arch/arm/mm/init.c
+++ b/arch/arm/mm/init.c
@@ -378,7 +378,11 @@ 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);
--
2.25.1