linux-kernel - [PATCH 1/2] soc: qcom: stats: fix 64-bit division

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Message-Id: <20231206123717.524009-1-arnd@kernel.org>
Date:   Wed,  6 Dec 2023 13:37:06 +0100
From:   Arnd Bergmann <arnd@...nel.org>
To:     Bjorn Andersson <andersson@...nel.org>
Cc:     Arnd Bergmann <arnd@...db.de>, Andy Gross <agross@...nel.org>,
        Konrad Dybcio <konrad.dybcio@...aro.org>,
        Stephen Boyd <swboyd@...omium.org>,
        Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>, linux-arm-msm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH 1/2] soc: qcom: stats: fix 64-bit division

From: Arnd Bergmann <arnd@...db.de>

Unguarded 64-bit division is not allowed on 32-bit kernels because this
is very slow. The result of trying anyway is a link failure:

arm-linux-gnueabi-ld: drivers/soc/qcom/qcom_stats.o: in function `qcom_ddr_stats_show':
qcom_stats.c:(.text+0x334): undefined reference to `__aeabi_uldivmod'

As this function is only used for debugging and not performance critical,
rewrite it to use div_u64() instead. ARCH_TIMER_FREQ is a multiple of
MSEC_PER_SEC anyway, so there is no loss in precisison.

Fixes: e84e61bdb97c ("soc: qcom: stats: Add DDR sleep stats")
Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
 drivers/soc/qcom/qcom_stats.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/soc/qcom/qcom_stats.c b/drivers/soc/qcom/qcom_stats.c
index 4763d62a8cb0..5ec8a754b22b 100644
--- a/drivers/soc/qcom/qcom_stats.c
+++ b/drivers/soc/qcom/qcom_stats.c
@@ -221,7 +221,7 @@ static int qcom_ddr_stats_show(struct seq_file *s, void *unused)
 
 	for (i = 0; i < ddr.entry_count; i++) {
 		/* Convert the period to ms */
-		entry[i].dur = mult_frac(MSEC_PER_SEC, entry[i].dur, ARCH_TIMER_FREQ);
+		entry[i].dur = div_u64(entry[i].dur, ARCH_TIMER_FREQ / MSEC_PER_SEC);
 	}
 
 	for (i = 0; i < ddr.entry_count; i++)
-- 
2.39.2