linux-kernel - Re: next-20241028: gcc-8-defconfig : ERROR: modpost: "__aeabi_uldivmod" [drivers/media/dvb-frontends/cxd2841er.ko] undefined!

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Message-Id: <e9971f03-e542-43ed-a8b5-8d79127f4693@app.fastmail.com>
Date: Fri, 01 Nov 2024 10:22:30 +0100
From: "Arnd Bergmann" <arnd@...db.de>
To: "Dan Carpenter" <dan.carpenter@...aro.org>,
 "Naresh Kamboju" <naresh.kamboju@...aro.org>
Cc: "Linux ARM" <linux-arm-kernel@...ts.infradead.org>,
 "open list" <linux-kernel@...r.kernel.org>,
 "Linux Regressions" <regressions@...ts.linux.dev>,
 lkft-triage@...ts.linaro.org, "Anders Roxell" <anders.roxell@...aro.org>,
 "Mauro Carvalho Chehab" <mchehab@...nel.org>,
 "Linux Media Mailing List" <linux-media@...r.kernel.org>
Subject: Re: next-20241028: gcc-8-defconfig : ERROR: modpost: "__aeabi_uldivmod"
 [drivers/media/dvb-frontends/cxd2841er.ko] undefined!

On Thu, Oct 31, 2024, at 12:27, Dan Carpenter wrote:
> Arnd, can you take a look at this?
>
> diff --git a/drivers/media/dvb-frontends/cxd2841er.c 
> b/drivers/media/dvb-frontends/cxd2841er.c
> index d925ca24183b..e3131f5c6708 100644
> --- a/drivers/media/dvb-frontends/cxd2841er.c
> +++ b/drivers/media/dvb-frontends/cxd2841er.c
> @@ -314,7 +314,7 @@ static u32 cxd2841er_calc_iffreq_xtal(enum 
> cxd2841er_xtal xtal, u32 ifhz)
>  	u64 tmp;
> 
>  	tmp = (u64) ifhz * 16777216;
> -	do_div(tmp, ((xtal == SONY_XTAL_24000) ? 48000000 : 41000000));
> +//	do_div(tmp, ((xtal == SONY_XTAL_24000) ? 48000000 : 41000000));
> 
>  	return (u32) tmp;
>  }

Not sure what is happening exactly, probably something where
__builtin_constant_p() is inconclusive. The patch below seems
to address it without impairing readability.

      Arnd

--- a/drivers/media/dvb-frontends/cxd2841er.c
+++ b/drivers/media/dvb-frontends/cxd2841er.c
@@ -311,12 +311,8 @@ static int cxd2841er_set_reg_bits(struct cxd2841er_priv *priv,

 static u32 cxd2841er_calc_iffreq_xtal(enum cxd2841er_xtal xtal, u32 ifhz)
 {
-       u64 tmp;
-
-       tmp = (u64) ifhz * 16777216;
-       do_div(tmp, ((xtal == SONY_XTAL_24000) ? 48000000 : 41000000));
-
-       return (u32) tmp;
+       return div_u64(ifhz * 16777216ull,
+                       (xtal == SONY_XTAL_24000) ? 48000000 : 41000000);
 }

 static u32 cxd2841er_calc_iffreq(u32 ifhz)