[PATCH] clk: Use div64_ul instead of do_div

[PATCH] clk: Use div64_ul instead of do_div

[cgel.zte]

From: Changcheng Deng <deng.changcheng@zte.com.cn>

do_div() does a 64-by-32 division. If the divisor is unsigned long, using
div64_ul can avoid truncation to 32-bit.

Reported-by: Zeal Robot <zealci@zte.com.cn>
Signed-off-by: Changcheng Deng <deng.changcheng@zte.com.cn>
---
 drivers/clk/clk-npcm7xx.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/clk/clk-npcm7xx.c b/drivers/clk/clk-npcm7xx.c
index e677bb5a784b..c75880af2b74 100644
--- a/drivers/clk/clk-npcm7xx.c
+++ b/drivers/clk/clk-npcm7xx.c
@@ -56,7 +56,7 @@ static unsigned long npcm7xx_clk_pll_recalc_rate(struct clk_hw *hw,
 	otdv2 = FIELD_GET(PLLCON_OTDV2, val);
 
 	ret = (u64)parent_rate * fbdv;
-	do_div(ret, indv * otdv1 * otdv2);
+	div64_ul(ret, indv * otdv1 * otdv2);
 
 	return ret;
 }
-- 
2.25.1

[PATCH v2] clk: Use div64_ul instead of do_div

[cgel.zte]

From: Changcheng Deng <deng.changcheng@zte.com.cn>

do_div() does a 64-by-32 division. Here the divisor is an unsigned long
which on some platforms is 64 bit wide. So use div64_ul instead of do_div
to avoid a possible truncation.

Reported-by: Zeal Robot <zealci@zte.com.cn>
Signed-off-by: Changcheng Deng <deng.changcheng@zte.com.cn>
---
 drivers/clk/clk-npcm7xx.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/clk/clk-npcm7xx.c b/drivers/clk/clk-npcm7xx.c
index e677bb5a784b..c75880af2b74 100644
--- a/drivers/clk/clk-npcm7xx.c
+++ b/drivers/clk/clk-npcm7xx.c
@@ -56,7 +56,7 @@ static unsigned long npcm7xx_clk_pll_recalc_rate(struct clk_hw *hw,
 	otdv2 = FIELD_GET(PLLCON_OTDV2, val);
 
 	ret = (u64)parent_rate * fbdv;
-	do_div(ret, indv * otdv1 * otdv2);
+	ret = div64_ul(ret, indv * otdv1 * otdv2);
 
 	return ret;
 }
-- 
2.25.1

Re: [PATCH v2] clk: Use div64_ul instead of do_div

[Stephen Boyd]

Please fix the subject. It should be "clk: npcm7xx: Use ..."

Quoting cgel.zte@gmail.com (2021-11-18 00:28:58)
> From: Changcheng Deng <deng.changcheng@zte.com.cn>
> 
> do_div() does a 64-by-32 division. Here the divisor is an unsigned long
> which on some platforms is 64 bit wide. So use div64_ul instead of do_div
> to avoid a possible truncation.
> 
> Reported-by: Zeal Robot <zealci@zte.com.cn>
> Signed-off-by: Changcheng Deng <deng.changcheng@zte.com.cn>