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authorDmitry Osipenko <digetx@gmail.com>2019-06-18 17:03:57 +0300
committerDaniel Lezcano <daniel.lezcano@linaro.org>2019-06-25 20:49:18 +0300
commit0ef6b01d024c24fad307b277cfa4a2be7d25dc29 (patch)
tree05aab71c90a634168a29b9b45cc04b9b8bb2b93c /drivers/clocksource
parentfc9babc2574691d3bbf0428f007b22261fed55c6 (diff)
downloadlinux-0ef6b01d024c24fad307b277cfa4a2be7d25dc29.tar.xz
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 <digetx@gmail.com> Acked-by: Jon Hunter <jonathanh@nvidia.com> Acked-by: Thierry Reding <treding@nvidia.com> Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Diffstat (limited to 'drivers/clocksource')
-rw-r--r--drivers/clocksource/timer-tegra.c13
1 files 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;
}