diff mbox series

[v3,2/4] clk: vc3: Fix 64 by 64 division

Message ID 20230817142211.311366-3-biju.das.jz@bp.renesas.com (mailing list archive)
State Changes Requested, archived
Headers show
Series Fix Versa3 clock mapping | expand

Commit Message

Biju Das Aug. 17, 2023, 2:22 p.m. UTC
Fix the below cocci warnings by replacing do_div()->div64_ul() and
bound the result with a max value of U16_MAX.

cocci warnings:
	drivers/clk/clk-versaclock3.c:404:2-8: WARNING: do_div() does a
	64-by-32 division, please consider using div64_ul instead.

Reported-by: Julia Lawall <julia.lawall@inria.fr>
Closes: https://lore.kernel.org/r/202307270841.yr5HxYIl-lkp@intel.com/
Fixes: 6e9aff555db7 ("clk: Add support for versa3 clock driver")
Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
---
v2->v3:
 * Added to this patch series.
v1->v2:
 * Added fixes tag.
---
 drivers/clk/clk-versaclock3.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

Comments

Stephen Boyd Aug. 22, 2023, 8:28 p.m. UTC | #1
Quoting Biju Das (2023-08-17 07:22:09)
> Fix the below cocci warnings by replacing do_div()->div64_ul() and
> bound the result with a max value of U16_MAX.
> 
> cocci warnings:
>         drivers/clk/clk-versaclock3.c:404:2-8: WARNING: do_div() does a
>         64-by-32 division, please consider using div64_ul instead.
> 
> Reported-by: Julia Lawall <julia.lawall@inria.fr>
> Closes: https://lore.kernel.org/r/202307270841.yr5HxYIl-lkp@intel.com/
> Fixes: 6e9aff555db7 ("clk: Add support for versa3 clock driver")
> Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
> ---
> v2->v3:
>  * Added to this patch series.
> v1->v2:
>  * Added fixes tag.
> ---
>  drivers/clk/clk-versaclock3.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/drivers/clk/clk-versaclock3.c b/drivers/clk/clk-versaclock3.c
> index 7ab2447bd203..3ded616a0d15 100644
> --- a/drivers/clk/clk-versaclock3.c
> +++ b/drivers/clk/clk-versaclock3.c
> @@ -401,9 +401,8 @@ static long vc3_pll_round_rate(struct clk_hw *hw, unsigned long rate,
>                 /* Determine best fractional part, which is 16 bit wide */
>                 div_frc = rate % *parent_rate;
>                 div_frc *= BIT(16) - 1;
> -               do_div(div_frc, *parent_rate);
>  
> -               vc3->div_frc = (u32)div_frc;
> +               vc3->div_frc = min_t(u64, div64_ul(div_frc, *parent_rate), U16_MAX);
>                 rate = (*parent_rate *
>                         (vc3->div_int * VC3_2_POW_16 + div_frc) / VC3_2_POW_16);

                                                            ^
Should this be vc3->div_frc now to get the clamped value? --|
Biju Das Aug. 23, 2023, 6:50 a.m. UTC | #2
Hi Stephen Boyd,

Thanks for the feedback.

> Subject: Re: [PATCH v3 2/4] clk: vc3: Fix 64 by 64 division
> 
> Quoting Biju Das (2023-08-17 07:22:09)
> > Fix the below cocci warnings by replacing do_div()->div64_ul() and
> > bound the result with a max value of U16_MAX.
> >
> > cocci warnings:
> >         drivers/clk/clk-versaclock3.c:404:2-8: WARNING: do_div() does a
> >         64-by-32 division, please consider using div64_ul instead.
> >
> > Reported-by: Julia Lawall <julia.lawall@inria.fr>
> > Closes:

> > Fixes: 6e9aff555db7 ("clk: Add support for versa3 clock driver")
> > Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
> > ---
> > v2->v3:
> >  * Added to this patch series.
> > v1->v2:
> >  * Added fixes tag.
> > ---
> >  drivers/clk/clk-versaclock3.c | 3 +--
> >  1 file changed, 1 insertion(+), 2 deletions(-)
> >
> > diff --git a/drivers/clk/clk-versaclock3.c
> > b/drivers/clk/clk-versaclock3.c index 7ab2447bd203..3ded616a0d15
> > 100644
> > --- a/drivers/clk/clk-versaclock3.c
> > +++ b/drivers/clk/clk-versaclock3.c
> > @@ -401,9 +401,8 @@ static long vc3_pll_round_rate(struct clk_hw *hw,
> unsigned long rate,
> >                 /* Determine best fractional part, which is 16 bit wide
> */
> >                 div_frc = rate % *parent_rate;
> >                 div_frc *= BIT(16) - 1;
> > -               do_div(div_frc, *parent_rate);
> >
> > -               vc3->div_frc = (u32)div_frc;
> > +               vc3->div_frc = min_t(u64, div64_ul(div_frc,
> > + *parent_rate), U16_MAX);
> >                 rate = (*parent_rate *
> >                         (vc3->div_int * VC3_2_POW_16 + div_frc) /
> > VC3_2_POW_16);
> 
>                                                             ^ Should this
> be vc3->div_frc now to get the clamped value? --|

Yes, it is clamped value. I will send next version fixing
this.

Cheers,
Biju
diff mbox series

Patch

diff --git a/drivers/clk/clk-versaclock3.c b/drivers/clk/clk-versaclock3.c
index 7ab2447bd203..3ded616a0d15 100644
--- a/drivers/clk/clk-versaclock3.c
+++ b/drivers/clk/clk-versaclock3.c
@@ -401,9 +401,8 @@  static long vc3_pll_round_rate(struct clk_hw *hw, unsigned long rate,
 		/* Determine best fractional part, which is 16 bit wide */
 		div_frc = rate % *parent_rate;
 		div_frc *= BIT(16) - 1;
-		do_div(div_frc, *parent_rate);
 
-		vc3->div_frc = (u32)div_frc;
+		vc3->div_frc = min_t(u64, div64_ul(div_frc, *parent_rate), U16_MAX);
 		rate = (*parent_rate *
 			(vc3->div_int * VC3_2_POW_16 + div_frc) / VC3_2_POW_16);
 	} else {