From ea08eeccae9297f7aabd2ef7f0c2517ac4549acc Mon Sep 17 00:00:00 2001
From: hc <hc@nodka.com>
Date: Tue, 20 Feb 2024 01:18:26 +0000
Subject: [PATCH] write in 30M
---
kernel/arch/arm/mach-mmp/time.c | 11 +++++++----
1 files changed, 7 insertions(+), 4 deletions(-)
diff --git a/kernel/arch/arm/mach-mmp/time.c b/kernel/arch/arm/mach-mmp/time.c
index 41b2e8a..708816c 100644
--- a/kernel/arch/arm/mach-mmp/time.c
+++ b/kernel/arch/arm/mach-mmp/time.c
@@ -43,18 +43,21 @@
static void __iomem *mmp_timer_base = TIMERS_VIRT_BASE;
/*
- * FIXME: the timer needs some delay to stablize the counter capture
+ * Read the timer through the CVWR register. Delay is required after requesting
+ * a read. The CR register cannot be directly read due to metastability issues
+ * documented in the PXA168 software manual.
*/
static inline uint32_t timer_read(void)
{
- int delay = 100;
+ uint32_t val;
+ int delay = 3;
__raw_writel(1, mmp_timer_base + TMR_CVWR(1));
while (delay--)
- cpu_relax();
+ val = __raw_readl(mmp_timer_base + TMR_CVWR(1));
- return __raw_readl(mmp_timer_base + TMR_CVWR(1));
+ return val;
}
static u64 notrace mmp_read_sched_clock(void)
--
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