From 5b644c7a218702668d7b610994e7dcbc3d4705d3 Mon Sep 17 00:00:00 2001 From: Magnus Damm Date: Tue, 28 Apr 2009 08:17:54 +0000 Subject: [PATCH] clocksource: improve sh_cmt clocksource overflow handling This patch improves the sh_cmt clocksource handling. Currently the counter value is ignored in the case of overflow. With this patch the overflow flag is read before and after reading the counter, removing any counter value and overflow flag mismatch issues. Signed-off-by: Magnus Damm Signed-off-by: Paul Mundt --- drivers/clocksource/sh_cmt.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) diff --git a/drivers/clocksource/sh_cmt.c b/drivers/clocksource/sh_cmt.c index c2475648961..d607ac2d516 100644 --- a/drivers/clocksource/sh_cmt.c +++ b/drivers/clocksource/sh_cmt.c @@ -111,16 +111,21 @@ static unsigned long sh_cmt_get_counter(struct sh_cmt_priv *p, int *has_wrapped) { unsigned long v1, v2, v3; + int o1, o2; + + o1 = sh_cmt_read(p, CMCSR) & p->overflow_bit; /* Make sure the timer value is stable. Stolen from acpi_pm.c */ do { + o2 = o1; v1 = sh_cmt_read(p, CMCNT); v2 = sh_cmt_read(p, CMCNT); v3 = sh_cmt_read(p, CMCNT); - } while (unlikely((v1 > v2 && v1 < v3) || (v2 > v3 && v2 < v1) - || (v3 > v1 && v3 < v2))); + o1 = sh_cmt_read(p, CMCSR) & p->overflow_bit; + } while (unlikely((o1 != o2) || (v1 > v2 && v1 < v3) + || (v2 > v3 && v2 < v1) || (v3 > v1 && v3 < v2))); - *has_wrapped = sh_cmt_read(p, CMCSR) & p->overflow_bit; + *has_wrapped = o1; return v2; } @@ -394,7 +399,7 @@ static cycle_t sh_cmt_clocksource_read(struct clocksource *cs) raw = sh_cmt_get_counter(p, &has_wrapped); if (unlikely(has_wrapped)) - raw = p->match_value; + raw += p->match_value; spin_unlock_irqrestore(&p->lock, flags); return value + raw;