This is an automated email from the ASF dual-hosted git repository.
jerpelea pushed a commit to branch releases/10.2
in repository https://gitbox.apache.org/repos/asf/incubator-nuttx.git
commit 9e717995bf076ec732ba150a6da855a91f1ee6da
Author: Abdelatif Guettouche <abdelatif.guettou...@espressif.com>
AuthorDate: Wed Oct 13 10:32:24 2021 +0200
xtensa_testset.c: Simplify the test-set function and remove some old
comments.
Signed-off-by: Abdelatif Guettouche <abdelatif.guettou...@espressif.com>
---
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 169ff10..4753926 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 */
