From: Arnd Bergmann <arnd@kernel.org>
To: Daniel Lezcano <daniel.lezcano@linaro.org>,
Thomas Gleixner <tglx@linutronix.de>,
Thierry Reding <thierry.reding@gmail.com>,
Jonathan Hunter <jonathanh@nvidia.com>,
Pohsun Su <pohsuns@nvidia.com>, Robert Lin <robelin@nvidia.com>
Cc: Arnd Bergmann <arnd@arndb.de>,
linux-kernel@vger.kernel.org, linux-tegra@vger.kernel.org
Subject: [PATCH] clocksource: tegra186: avoid 64-bit division
Date: Fri, 20 Jun 2025 13:19:35 +0200 [thread overview]
Message-ID: <20250620111939.3395525-1-arnd@kernel.org> (raw)
From: Arnd Bergmann <arnd@arndb.de>
The newly added function causes a build failure on 32-bit targets with
older compiler version such as gcc-10:
arm-linux-gnueabi-ld: drivers/clocksource/timer-tegra186.o: in function `tegra186_wdt_get_timeleft':
timer-tegra186.c:(.text+0x3c2): undefined reference to `__aeabi_uldivmod'
The calculation can trivially be changed to avoid the division entirely,
as USEC_PER_SEC is a multiple of 5. Change both such calculation for
consistency, even though gcc apparently managed to optimize the other one
properly already.
Fixes: 28c842c8b0f5 ("clocksource/drivers/timer-tegra186: Add WDIOC_GETTIMELEFT support")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
drivers/clocksource/timer-tegra186.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/clocksource/timer-tegra186.c b/drivers/clocksource/timer-tegra186.c
index e5394f98a02e..bd3d443e41cd 100644
--- a/drivers/clocksource/timer-tegra186.c
+++ b/drivers/clocksource/timer-tegra186.c
@@ -159,7 +159,7 @@ static void tegra186_wdt_enable(struct tegra186_wdt *wdt)
tmr_writel(wdt->tmr, TMRCSSR_SRC_USEC, TMRCSSR);
/* configure timer (system reset happens on the fifth expiration) */
- value = TMRCR_PTV(wdt->base.timeout * USEC_PER_SEC / 5) |
+ value = TMRCR_PTV(wdt->base.timeout * (USEC_PER_SEC / 5)) |
TMRCR_PERIODIC | TMRCR_ENABLE;
tmr_writel(wdt->tmr, value, TMRCR);
@@ -267,7 +267,7 @@ static unsigned int tegra186_wdt_get_timeleft(struct watchdog_device *wdd)
* counter value to the time of the counter expirations that
* remain.
*/
- timeleft += (((u64)wdt->base.timeout * USEC_PER_SEC) / 5) * (4 - expiration);
+ timeleft += (u64)wdt->base.timeout * (USEC_PER_SEC / 5) * (4 - expiration);
/*
* Convert the current counter value to seconds,
--
2.39.5
next reply other threads:[~2025-06-20 11:19 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-06-20 11:19 Arnd Bergmann [this message]
2025-06-24 10:06 ` Jon Hunter
2025-06-24 10:20 ` Arnd Bergmann
2025-07-15 11:12 ` Daniel Lezcano
2025-07-23 7:17 ` [tip: timers/clocksource] clocksource/drivers/tegra186: Avoid " tip-bot2 for Arnd Bergmann
2025-07-25 10:31 ` tip-bot2 for Arnd Bergmann
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