linux-kernel - [PATCH] mmc: mtk-sd: use div64_u64() instead of do

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Date:   Wed,  9 Feb 2022 00:38:47 -0800
From:   Qing Wang <wangqing@...o.com>
To:     Chaotian Jing <chaotian.jing@...iatek.com>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        linux-mmc@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, linux-kernel@...r.kernel.org
Cc:     Wang Qing <wangqing@...o.com>
Subject: [PATCH] mmc: mtk-sd: 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/mmc/host/mtk-sd.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/mmc/host/mtk-sd.c b/drivers/mmc/host/mtk-sd.c
index 65037e1..777c9a8
--- a/drivers/mmc/host/mtk-sd.c
+++ b/drivers/mmc/host/mtk-sd.c
@@ -766,7 +766,7 @@ static u64 msdc_timeout_cal(struct msdc_host *host, u64 ns, u64 clks)
 		clk_ns  = 1000000000ULL;
 		do_div(clk_ns, mmc->actual_clock);
 		timeout = ns + clk_ns - 1;
-		do_div(timeout, clk_ns);
+		div64_u64(timeout, clk_ns);
 		timeout += clks;
 		/* in 1048576 sclk cycle unit */
 		timeout = DIV_ROUND_UP(timeout, BIT(20));
-- 
2.7.4