linux-kernel - [PATCH] media: dvb-frontends: use div64_u64() instead of do

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Date:   Wed,  9 Feb 2022 00:38:16 -0800
From:   Qing Wang <wangqing@...o.com>
To:     Mauro Carvalho Chehab <mchehab@...nel.org>,
        linux-media@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     Wang Qing <wangqing@...o.com>
Subject: [PATCH] media: dvb-frontends: use div64_u64() instead of do_div()

From: Wang Qing <wangqing@...o.com>

do_div() does a 64-by-32 division.
When the divisor is u64, do_div() truncates it to 32 bits, this means it
can test non-zero and be truncated to zero for division.

fix do_div.cocci warning:
do_div() does a 64-by-32 division, please consider using div64_u64 instead.

Signed-off-by: Wang Qing <wangqing@...o.com>
---
 drivers/media/dvb-frontends/tda10048.c     | 2 +-
 drivers/media/dvb-frontends/tda18271c2dd.c | 4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/media/dvb-frontends/tda10048.c b/drivers/media/dvb-frontends/tda10048.c
index d1d206e..1ce2e67
--- a/drivers/media/dvb-frontends/tda10048.c
+++ b/drivers/media/dvb-frontends/tda10048.c
@@ -344,7 +344,7 @@ static int tda10048_set_wref(struct dvb_frontend *fe, u32 sample_freq_hz,
 	z = 7 * sample_freq_hz;
 	do_div(t, z);
 	t += 5;
-	do_div(t, 10);
+	div64_u64(t, 10);
 
 	tda10048_writereg(state, TDA10048_TIME_WREF_LSB, (u8)t);
 	tda10048_writereg(state, TDA10048_TIME_WREF_MID1, (u8)(t >> 8));
diff --git a/drivers/media/dvb-frontends/tda18271c2dd.c b/drivers/media/dvb-frontends/tda18271c2dd.c
index a3483448..fd92878
--- a/drivers/media/dvb-frontends/tda18271c2dd.c
+++ b/drivers/media/dvb-frontends/tda18271c2dd.c
@@ -328,7 +328,7 @@ static int CalcMainPLL(struct tda_state *state, u32 freq)
 
 	OscFreq = (u64) freq * (u64) Div;
 	OscFreq *= (u64) 16384;
-	do_div(OscFreq, (u64)16000000);
+	do_div(OscFreq, 16000000);
 	MainDiv = OscFreq;
 
 	state->m_Regs[MPD] = PostDiv & 0x77;
@@ -352,7 +352,7 @@ static int CalcCalPLL(struct tda_state *state, u32 freq)
 	OscFreq = (u64)freq * (u64)Div;
 	/* CalDiv = u32( OscFreq * 16384 / 16000000 ); */
 	OscFreq *= (u64)16384;
-	do_div(OscFreq, (u64)16000000);
+	do_div(OscFreq, 16000000);
 	CalDiv = OscFreq;
 
 	state->m_Regs[CPD] = PostDiv;
-- 
2.7.4