[U-Boot] [PATCH 2/6] riscv: remove invalid dcache flush implementation

[Lukas Auer]

The fence instruction is used to enforce device I/O and memory ordering
constraints in RISC-V. It does not directly affect the data cache and
particular cannot be used to flush or invalidate it. RISC-V does not
have instructions for explicit cache control. Remove the
flush_dcache_all implementation and its use in all dcache-specific
functions in lib/cache.c.

This also adds a missing new line between flush_dcache_all and
flush_dcache_range in lib/cache.c.

Signed-off-by: Lukas Auer <lukas.auer at aisec.fraunhofer.de>
---
This patch only removes the implementation itself and its use in
dcache-specific functions in lib/cache.c. There are more uses of it in
arch/riscv/, which this patch does not remove.

 arch/riscv/lib/cache.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/arch/riscv/lib/cache.c b/arch/riscv/lib/cache.c
index ae5c60716f..203e287612 100644
--- a/arch/riscv/lib/cache.c
+++ b/arch/riscv/lib/cache.c
@@ -13,11 +13,10 @@ void invalidate_icache_all(void)
 
 void flush_dcache_all(void)
 {
-	asm volatile ("fence" :::"memory");
 }
+
 void flush_dcache_range(unsigned long start, unsigned long end)
 {
-	flush_dcache_all();
 }
 
 void invalidate_icache_range(unsigned long start, unsigned long end)
@@ -31,7 +30,6 @@ void invalidate_icache_range(unsigned long start, unsigned long end)
 
 void invalidate_dcache_range(unsigned long start, unsigned long end)
 {
-	flush_dcache_all();
 }
 
 void cache_flush(void)
-- 
2.20.1