[PATCH v2 25/52] m68k: apollo: Replace set but not used variable by READ_ONCE()

[Geert Uytterhoeven]

When building with W=1:

    arch/m68k/apollo/config.c: In function ‘dn_timer_int’:
    arch/m68k/apollo/config.c:171:32: warning: variable ‘x’ set but not used [-Wunused-but-set-variable]
      149 |         volatile unsigned char x;
	  |                                ^

Fix this by using READ_ONCE(), and removing the variable.
As READ_ONCE() casts to volatile internally, remove the existing cast.
Deduplicate the remaining casts by introducing an intermediary.

Signed-off-by: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
Acked-by: Arnd Bergmann <arnd@xxxxxxxx>
---
v2:
  - Add Acked-by,
  - Remove volatile and dedup casts, as suggested by Finn.
---
 arch/m68k/apollo/config.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/m68k/apollo/config.c b/arch/m68k/apollo/config.c
index 0e6801eecbaf6361..7afefb0191504d4e 100644
--- a/arch/m68k/apollo/config.c
+++ b/arch/m68k/apollo/config.c
@@ -146,13 +146,13 @@ void __init config_apollo(void)
 
 irqreturn_t dn_timer_int(int irq, void *dev_id)
 {
-	volatile unsigned char x;
+	unsigned char *at = (unsigned char *)apollo_timer;
 
 	legacy_timer_tick(1);
 	timer_heartbeat();
 
-	x = *(volatile unsigned char *)(apollo_timer + 3);
-	x = *(volatile unsigned char *)(apollo_timer + 5);
+	READ_ONCE(*(at + 3));
+	READ_ONCE(*(at + 5));
 
 	return IRQ_HANDLED;
 }
-- 
2.34.1