[PATCH AUTOSEL 4.19 041/158] arm64: mm: make CONFIG_ZONE_DMA32 configurable

[Sasha Levin]

From: Miles Chen <miles.chen@xxxxxxxxxxxx>

[ Upstream commit 0c1f14ed12262f45a3af1d588e4d7bd12438b8f5 ]

This change makes CONFIG_ZONE_DMA32 defuly y and allows users
to overwrite it only when CONFIG_EXPERT=y.

For the SoCs that do not need CONFIG_ZONE_DMA32, this is the
first step to manage all available memory by a single
zone(normal zone) to reduce the overhead of multiple zones.

The change also fixes a build error when CONFIG_NUMA=y and
CONFIG_ZONE_DMA32=n.

arch/arm64/mm/init.c:195:17: error: use of undeclared identifier 'ZONE_DMA32'
                max_zone_pfns[ZONE_DMA32] = PFN_DOWN(max_zone_dma_phys());

Change since v1:
1. only expose CONFIG_ZONE_DMA32 when CONFIG_EXPERT=y
2. remove redundant IS_ENABLED(CONFIG_ZONE_DMA32)

Cc: Robin Murphy <robin.murphy@xxxxxxx>
Signed-off-by: Miles Chen <miles.chen@xxxxxxxxxxxx>
Signed-off-by: Catalin Marinas <catalin.marinas@xxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 arch/arm64/Kconfig   | 3 ++-
 arch/arm64/mm/init.c | 5 +++--
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 8790a29d0af4..e3ebece79617 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -251,7 +251,8 @@ config GENERIC_CALIBRATE_DELAY
 	def_bool y
 
 config ZONE_DMA32
-	def_bool y
+	bool "Support DMA32 zone" if EXPERT
+	default y
 
 config HAVE_GENERIC_GUP
 	def_bool y
diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index 774c3e17c798..29d2f425806e 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -233,8 +233,9 @@ static void __init zone_sizes_init(unsigned long min, unsigned long max)
 {
 	unsigned long max_zone_pfns[MAX_NR_ZONES]  = {0};
 
-	if (IS_ENABLED(CONFIG_ZONE_DMA32))
-		max_zone_pfns[ZONE_DMA32] = PFN_DOWN(max_zone_dma_phys());
+#ifdef CONFIG_ZONE_DMA32
+	max_zone_pfns[ZONE_DMA32] = PFN_DOWN(max_zone_dma_phys());
+#endif
 	max_zone_pfns[ZONE_NORMAL] = max;
 
 	free_area_init_nodes(max_zone_pfns);
-- 
2.20.1