From: Daniel Lezcano <daniel.lezcano@linaro.org>
To: tglx@linutronix.de
Cc: linux-kernel@vger.kernel.org, Dmitry Osipenko <digetx@gmail.com>,
Jon Hunter <jonathanh@nvidia.com>,
Thierry Reding <treding@nvidia.com>,
Thierry Reding <thierry.reding@gmail.com>,
linux-tegra@vger.kernel.org (open list:TEGRA ARCHITECTURE
SUPPORT)
Subject: [PATCH 22/25] clocksource/drivers/tegra: Cycles can't be 0
Date: Wed, 26 Jun 2019 16:46:48 +0200 [thread overview]
Message-ID: <20190626144651.16742-22-daniel.lezcano@linaro.org> (raw)
In-Reply-To: <20190626144651.16742-1-daniel.lezcano@linaro.org>
From: Dmitry Osipenko <digetx@gmail.com>
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>
---
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;
}
--
2.17.1
next prev parent reply other threads:[~2019-06-26 14:48 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-26 14:43 [GIT PULL] timer drivers for v5.4 Daniel Lezcano
2019-06-26 14:46 ` [PATCH 01/25] clocksource/drivers/timer-meson6: Update with SPDX Licence identifier Daniel Lezcano
2019-06-26 14:46 ` [PATCH 02/25] clocksource/drivers/ixp4xx: Implement delay timer Daniel Lezcano
2019-06-26 14:46 ` [PATCH 03/25] clocksource/drivers/arc_timer: Use BIT() instead of _BITUL() Daniel Lezcano
2019-06-26 14:46 ` [PATCH 04/25] clocksource/drivers/exynos_mct: Increase priority over ARM arch timer Daniel Lezcano
2019-06-26 14:46 ` [PATCH 05/25] clocksource/drivers/tegra: Support per-CPU timers on all Tegra's Daniel Lezcano
2019-06-26 14:46 ` [PATCH 06/25] clocksource/drivers/tegra: Unify timer code Daniel Lezcano
2019-06-26 14:46 ` [PATCH 07/25] clocksource/drivers/tegra: Reset hardware state on init Daniel Lezcano
2019-06-26 14:46 ` [PATCH 08/25] clocksource/drivers/tegra: Replace readl/writel with relaxed versions Daniel Lezcano
2019-06-26 14:46 ` [PATCH 09/25] clocksource/drivers/tegra: Release all IRQ's on request_irq() error Daniel Lezcano
2019-06-26 14:46 ` [PATCH 10/25] clocksource/drivers/tegra: Minor code clean up Daniel Lezcano
2019-06-26 14:46 ` [PATCH 11/25] clocksource/drivers/tegra: Support COMPILE_TEST universally Daniel Lezcano
2019-06-26 14:46 ` [PATCH 12/25] clocksource/drivers/tegra: Lower clocksource rating for some Tegra's Daniel Lezcano
2019-06-26 14:46 ` [PATCH 13/25] clocksource/drivers/tegra: Rename timer-tegra20.c to timer-tegra.c Daniel Lezcano
2019-06-26 14:46 ` [PATCH 14/25] clocksource/drivers/sysctr: Add nxp system counter timer driver support Daniel Lezcano
2019-06-26 14:46 ` [PATCH 15/25] clocksource/drivers/arm_arch_timer: Extract elf_hwcap use to arch-helper Daniel Lezcano
2019-06-26 14:46 ` [PATCH 16/25] clocksource/drivers/tegra: Restore timer rate on Tegra210 Daniel Lezcano
2019-06-26 14:46 ` [PATCH 17/25] clocksource/drivers/tegra: Remove duplicated use of per_cpu_ptr Daniel Lezcano
2019-06-26 14:46 ` [PATCH 18/25] clocksource/drivers/tegra: Set and use timer's period Daniel Lezcano
2019-06-26 14:46 ` [PATCH 19/25] clocksource/drivers/tegra: Drop unneeded typecasting in one place Daniel Lezcano
2019-06-26 14:46 ` [PATCH 20/25] clocksource/drivers/tegra: Add verbose definition for 1MHz constant Daniel Lezcano
2019-06-26 14:46 ` [PATCH 21/25] clocksource/drivers/tegra: Restore base address before cleanup Daniel Lezcano
2019-06-26 14:46 ` Daniel Lezcano [this message]
2019-06-26 14:46 ` [PATCH 23/25] clocksource/drivers/tegra: Set up maximum-ticks limit properly Daniel Lezcano
2019-06-26 14:46 ` [PATCH 24/25] clocksource/drivers/davinci: Add support for clockevents Daniel Lezcano
2019-06-26 14:46 ` [PATCH 25/25] clocksource/drivers/davinci: Add support for clocksource Daniel Lezcano
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