linux-kernel - [PATCH AUTOSEL 6.13 01/15] media: cxd2841er: fix 64-bit division on gcc-9

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Message-Id: <20250128175346.1197097-1-sashal@kernel.org>
Date: Tue, 28 Jan 2025 12:53:32 -0500
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Cc: Arnd Bergmann <arnd@...db.de>,
	Dan Carpenter <dan.carpenter@...aro.org>,
	Naresh Kamboju <naresh.kamboju@...aro.org>,
	Linux Kernel Functional Testing <lkft@...aro.org>,
	Hans Verkuil <hverkuil@...all.nl>,
	Sasha Levin <sashal@...nel.org>,
	aospan@...zon.com,
	mchehab@...nel.org,
	linux-media@...r.kernel.org
Subject: [PATCH AUTOSEL 6.13 01/15] media: cxd2841er: fix 64-bit division on gcc-9

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

[ Upstream commit 8d46603eeeb4c6abff1d2e49f2a6ae289dac765e ]

It appears that do_div() once more gets confused by a complex
expression that ends up not quite being constant despite
__builtin_constant_p() thinking it is:

ERROR: modpost: "__aeabi_uldivmod" [drivers/media/dvb-frontends/cxd2841er.ko] undefined!

Use div_u64() instead, forcing the expression to be evaluated
first, and making it a bit more readable.

Cc: Dan Carpenter <dan.carpenter@...aro.org>
Reported-by: Naresh Kamboju <naresh.kamboju@...aro.org>
Closes: https://lore.kernel.org/linux-media/CA+G9fYvvNm-aYodLaAwwTjEGtX0YxR-1R14FOA5aHKt0sSVsYg@mail.gmail.com/
Reported-by: Linux Kernel Functional Testing <lkft@...aro.org>
Closes: https://lore.kernel.org/linux-media/CA+G9fYvvNm-aYodLaAwwTjEGtX0YxR-1R14FOA5aHKt0sSVsYg@mail.gmail.com/
Signed-off-by: Arnd Bergmann <arnd@...db.de>
Signed-off-by: Hans Verkuil <hverkuil@...all.nl>
[hverkuil: added Closes tags]
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/media/dvb-frontends/cxd2841er.c | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/drivers/media/dvb-frontends/cxd2841er.c b/drivers/media/dvb-frontends/cxd2841er.c
index d925ca24183b5..415f1f91cc307 100644
--- 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)
-- 
2.39.5