Hi Biju,
On Thu, Jul 27, 2023 at 11:19 AM Biju Das <biju.das.jz@xxxxxxxxxxxxxx> wrote:
> > versaclock3.c:404:2-8: WARNING: do_div() does a 64-by-32 division, please
> > consider using div64_ul instead. (fwd)
> >
> > On Thu, 27 Jul 2023, Biju Das wrote:
> > > The reproduce link is not working for me.
> > >
> > > Can you please provide instruction to reproduce this issue?
> >
> > I don't think it's intended to be reproduced. The issue is just that a
> > long value is being passed to an integer that is 32 bit. If the long
> > value will never be very big, then you can just ignore the warning.
>
> The rate values are well below max 32 bit, 4294967296. So I guess, it is ok.
The type of the parent_rate in/output parameter of clk_ops.round_rate()
is unsigned long. Hence you should use div64_ul().
> > > > versaclock3.c:404:2-8: WARNING: do_div() does a 64-by-32 division,
> > > > please consider using div64_ul instead. (fwd)
> > > >
> > > >
> > > >
> > > > ---------- Forwarded message ----------
> > > > Date: Thu, 27 Jul 2023 08:50:37 +0800
> > > > From: kernel test robot <lkp@xxxxxxxxx>
> > > > To: oe-kbuild@xxxxxxxxxxxxxxx
> > > > Cc: lkp@xxxxxxxxx, Julia Lawall <julia.lawall@xxxxxxxx>
> > > > Subject: [linux-next:master 2742/4710] drivers/clk/clk-
> > > > versaclock3.c:404:2-8:
> > > > WARNING: do_div() does a 64-by-32 division,
> > > > please consider using div64_ul instead.
> > > >
> > > > BCC: lkp@xxxxxxxxx
> > > > CC: oe-kbuild-all@xxxxxxxxxxxxxxx
> > > > CC: Linux Memory Management List <linux-mm@xxxxxxxxx>
> > > > TO: Biju Das <biju.das.jz@xxxxxxxxxxxxxx>
> > > > CC: Stephen Boyd <sboyd@xxxxxxxxxx>
> > > >
> > > > tree:
> > > >
> > > > If you fix the issue in a separate patch/commit (i.e. not just a new
> > > > version of the same patch/commit), kindly add following tags
> > > > | Reported-by: kernel test robot <lkp@xxxxxxxxx>
> > > > | Reported-by: Julia Lawall <julia.lawall@xxxxxxxx>
> > > > | Closes:
> > > %2BsY49B78%3D&reserved=0
> > > >
> > > > cocci warnings: (new ones prefixed by >>)
> > > > >> drivers/clk/clk-versaclock3.c:404:2-8: WARNING: do_div() does a
> > > > >> 64-
> > > > by-32 division, please consider using div64_ul instead.
> > > >
> > > > vim +404 drivers/clk/clk-versaclock3.c
> > > >
> > > > 6e9aff555db7b6 Biju Das 2023-07-05 382
> > > > 6e9aff555db7b6 Biju Das 2023-07-05 383 static long
> > > > vc3_pll_round_rate(struct clk_hw *hw, unsigned long rate,
> > > > 6e9aff555db7b6 Biju Das 2023-07-05 384
> > unsigned
> > > > long *parent_rate)
> > > > 6e9aff555db7b6 Biju Das 2023-07-05 385 {
> > > > 6e9aff555db7b6 Biju Das 2023-07-05 386 struct vc3_hw_data *vc3 =
> > > > container_of(hw, struct vc3_hw_data, hw);
> > > > 6e9aff555db7b6 Biju Das 2023-07-05 387 const struct vc3_pll_data
> > *pll
> > > > = vc3->data;
> > > > 6e9aff555db7b6 Biju Das 2023-07-05 388 u64 div_frc;
> > > > 6e9aff555db7b6 Biju Das 2023-07-05 389
> > > > 6e9aff555db7b6 Biju Das 2023-07-05 390 if (rate < pll->vco_min)
> > > > 6e9aff555db7b6 Biju Das 2023-07-05 391 rate = pll->vco_min;
> > > > 6e9aff555db7b6 Biju Das 2023-07-05 392 if (rate > pll->vco_max)
> > > > 6e9aff555db7b6 Biju Das 2023-07-05 393 rate = pll->vco_max;
> > > > 6e9aff555db7b6 Biju Das 2023-07-05 394
> > > > 6e9aff555db7b6 Biju Das 2023-07-05 395 vc3->div_int = rate /
> > > > *parent_rate;
> > > > 6e9aff555db7b6 Biju Das 2023-07-05 396
> > > > 6e9aff555db7b6 Biju Das 2023-07-05 397 if (pll->num == VC3_PLL2)
> > {
> > > > 6e9aff555db7b6 Biju Das 2023-07-05 398 if (vc3->div_int >
> > 0x7ff)
> > > > 6e9aff555db7b6 Biju Das 2023-07-05 399 rate =
> > *parent_rate
> > > > * 0x7ff;
> > > > 6e9aff555db7b6 Biju Das 2023-07-05 400
> > > > 6e9aff555db7b6 Biju Das 2023-07-05 401 /* Determine best
> > > > fractional part, which is 16 bit wide */
> > > > 6e9aff555db7b6 Biju Das 2023-07-05 402 div_frc = rate %
> > > > *parent_rate;
> > > > 6e9aff555db7b6 Biju Das 2023-07-05 403 div_frc *= BIT(16) -
> > 1;
> > > > 6e9aff555db7b6 Biju Das 2023-07-05 @404 do_div(div_frc,
> > > > *parent_rate);
> > > > 6e9aff555db7b6 Biju Das 2023-07-05 405
> > > > 6e9aff555db7b6 Biju Das 2023-07-05 406 vc3->div_frc =
> > > > (u32)div_frc;
> > > > 6e9aff555db7b6 Biju Das 2023-07-05 407 rate = (*parent_rate
> > *
> > > > 6e9aff555db7b6 Biju Das 2023-07-05 408 (vc3->div_int
> > *
> > > > VC3_2_POW_16 + div_frc) / VC3_2_POW_16);
> > > > 6e9aff555db7b6 Biju Das 2023-07-05 409 } else {
> > > > 6e9aff555db7b6 Biju Das 2023-07-05 410 rate = *parent_rate
> > *
> > > > vc3->div_int;
> > > > 6e9aff555db7b6 Biju Das 2023-07-05 411 }
> > > > 6e9aff555db7b6 Biju Das 2023-07-05 412
> > > > 6e9aff555db7b6 Biju Das 2023-07-05 413 return rate;
> > > > 6e9aff555db7b6 Biju Das 2023-07-05 414 }
> > > > 6e9aff555db7b6 Biju Das 2023-07-05 415
> > > >
> > > > --
> > > > 0-DAY CI Kernel Test Service
> > >
--
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
