From 0ef6b01d024c24fad307b277cfa4a2be7d25dc29 Mon Sep 17 00:00:00 2001 From: Dmitry Osipenko Date: Tue, 18 Jun 2019 17:03:57 +0300 Subject: [PATCH] clocksource/drivers/tegra: Cycles can't be 0 Tegra's timer uses n+1 scheme for the counter, i.e. timer will fire after one tick if 0 is loaded. The minimum and maximum numbers of oneshot ticks are defined by clockevents_config_and_register(min, max) invocation and the min value is set to 1 tick. Hence "cycles" value can't ever be 0, unless it's a bug in clocksource core. Signed-off-by: Dmitry Osipenko Acked-by: Jon Hunter Acked-by: Thierry Reding Signed-off-by: Daniel Lezcano --- drivers/clocksource/timer-tegra.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) diff --git a/drivers/clocksource/timer-tegra.c b/drivers/clocksource/timer-tegra.c index 8e70f38f1898..a907e71065bd 100644 --- a/drivers/clocksource/timer-tegra.c +++ b/drivers/clocksource/timer-tegra.c @@ -56,9 +56,16 @@ static int tegra_timer_set_next_event(unsigned long cycles, { void __iomem *reg_base = timer_of_base(to_timer_of(evt)); - writel_relaxed(TIMER_PTV_EN | - ((cycles > 1) ? (cycles - 1) : 0), /* n+1 scheme */ - reg_base + TIMER_PTV); + /* + * Tegra's timer uses n+1 scheme for the counter, i.e. timer will + * fire after one tick if 0 is loaded. + * + * The minimum and maximum numbers of oneshot ticks are defined + * by clockevents_config_and_register(1, 0x1fffffff + 1) invocation + * below in the code. Hence the cycles (ticks) can't be outside of + * a range supportable by hardware. + */ + writel_relaxed(TIMER_PTV_EN | (cycles - 1), reg_base + TIMER_PTV); return 0; } -- 2.39.2