From eeb68bda3d808aba0dace20b72eef3a889bfe7fc Mon Sep 17 00:00:00 2001 From: Abdelatif Guettouche Date: Wed, 13 Oct 2021 10:32:24 +0200 Subject: [PATCH] xtensa_testset.c: Simplify the test-set function and remove some old comments. Signed-off-by: Abdelatif Guettouche --- arch/xtensa/src/common/xtensa_testset.c | 33 +++---------------------- 1 file changed, 4 insertions(+), 29 deletions(-) diff --git a/arch/xtensa/src/common/xtensa_testset.c b/arch/xtensa/src/common/xtensa_testset.c index 169ff1085f..4753926f78 100644 --- a/arch/xtensa/src/common/xtensa_testset.c +++ b/arch/xtensa/src/common/xtensa_testset.c @@ -56,8 +56,9 @@ static inline uint32_t xtensa_compareset(volatile uint32_t *addr, __asm__ __volatile__ ( "WSR %2, SCOMPARE1\n" /* Initialize SCOMPARE1 */ - "S32C1I %0, %1, 0\n" /* Store id into the lock, if the lock is the - * same as comparel. Otherwise, no write-access */ + "S32C1I %0, %1, 0\n" /* Store the compare value into the lock, + * if the lock is the same as compare1. + * Otherwise, no write-access */ : "=r"(set) : "r"(addr), "r"(compare), "0"(set) ); @@ -90,36 +91,10 @@ static inline uint32_t xtensa_compareset(volatile uint32_t *addr, spinlock_t up_testset(volatile spinlock_t *lock) { - spinlock_t prev; - /* Perform the 32-bit compare and set operation */ - prev = xtensa_compareset((volatile uint32_t *)lock, + return xtensa_compareset((volatile uint32_t *)lock, SP_UNLOCKED, SP_LOCKED); - - /* xtensa_compareset() should return either SP_UNLOCKED if the spinlock - * was locked or SP_LOCKED or possibly ~SP_UNLOCKED if the spinlock was - * not locked: - * - * "In the RE-2013.0 release and after, there is a slight change in the - * semantics of the S32C1I instruction. Nothing is changed about the - * operation on memory. In rare cases the resulting value in register - * at can be different in this and later releases. The rule still holds - * that memory has been written if and only if the register result - * equals SCOMPARE1. - * - * "The difference is that in some cases where memory has not been - * written, the instruction returns ~SCOMPARE1 instead of the current - * value of memory. Although this change can, in principle, affect - * the operation of code, scanning all internal Cadence code produced - * no examples where this change would change the operation of the - * code." - * - * In any case, the return value of SP_UNLOCKED can be trusted and will - * always mean that the spinlock was set. - */ - - return (prev == SP_UNLOCKED) ? SP_UNLOCKED : SP_LOCKED; } #endif /* CONFIG_SPINLOCK */