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Date:   Wed, 6 Dec 2023 15:16:58 +0100
From:   Uwe =?utf-8?Q?Kleine-K=C3=B6nig?= <u.kleine-koenig@pengutronix.de>
To:     Arnd Bergmann <arnd@kernel.org>
Cc:     Bjorn Andersson <andersson@kernel.org>,
        Arnd Bergmann <arnd@arndb.de>, Andy Gross <agross@kernel.org>,
        Konrad Dybcio <konrad.dybcio@linaro.org>,
        Stephen Boyd <swboyd@chromium.org>,
        linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] soc: qcom: stats: fix 64-bit division
Message-ID: <20231206141658.kjpjwjy7utdux6b5@pengutronix.de>
References: <20231206123717.524009-1-arnd@kernel.org>
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Hallo Arnd,

On Wed, Dec 06, 2023 at 01:37:06PM +0100, Arnd Bergmann wrote:
> 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:
>=20
> arm-linux-gnueabi-ld: drivers/soc/qcom/qcom_stats.o: in function `qcom_dd=
r_stats_show':
> qcom_stats.c:(.text+0x334): undefined reference to `__aeabi_uldivmod'
>=20
> 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.

Maybe add this information in a comment?

We have

	#define ARCH_TIMER_FREQ         19200000

so it's a multiple of MSEC_PER_SEC (=3D 1000) indeed.

Reviewed-by: Uwe Kleine-K=F6nig <u.kleine-koenig@pengutronix.de>

Best regards
Uwe

--=20
Pengutronix e.K.                           | Uwe Kleine-K=F6nig            |
Industrial Linux Solutions                 | https://www.pengutronix.de/ |

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