linux-kernel - drivers/clk/rockchip/clk-pll.c:912:2-8: WARNING: do_div() does a 64-by-32 division, please consider using div64

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Message-ID: <alpine.DEB.2.22.394.2401201801080.3267@hadrien>
Date: Sat, 20 Jan 2024 18:01:53 +0100 (CET)
From: Julia Lawall <julia.lawall@...ia.fr>
To: Elaine Zhang <zhangqing@...k-chips.com>, Heiko Stuebner <heiko@...ech.de>, 
    Sebastian Reichel <sebastian.reichel@...labora.com>
cc: linux-kernel@...r.kernel.org, oe-kbuild-all@...ts.linux.dev
Subject: drivers/clk/rockchip/clk-pll.c:912:2-8: WARNING: do_div() does a
 64-by-32 division, please consider using div64_u64 instead. (fwd)



---------- Forwarded message ----------
Date: Sun, 21 Jan 2024 00:55:25 +0800
From: kernel test robot <lkp@...el.com>
To: oe-kbuild@...ts.linux.dev
Cc: lkp@...el.com, Julia Lawall <julia.lawall@...ia.fr>
Subject: drivers/clk/rockchip/clk-pll.c:912:2-8: WARNING: do_div() does a
    64-by-32 division, please consider using div64_u64 instead.

BCC: lkp@...el.com
CC: oe-kbuild-all@...ts.linux.dev
CC: linux-kernel@...r.kernel.org
TO: Elaine Zhang <zhangqing@...k-chips.com>
CC: Heiko Stuebner <heiko@...ech.de>
CC: Sebastian Reichel <sebastian.reichel@...labora.com>

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   9d64bf433c53cab2f48a3fff7a1f2a696bc5229a
commit: 8f6594494b1cb0ad14493795b436413cfe64a0f8 clk: rockchip: add pll type for RK3588
date:   1 year, 2 months ago
:::::: branch date: 18 hours ago
:::::: commit date: 1 year, 2 months ago
config: arm-randconfig-r062-20240117 (https://download.01.org/0day-ci/archive/20240121/202401210007.174n0NM0-lkp@intel.com/config)
compiler: clang version 18.0.0git (https://github.com/llvm/llvm-project 9bde5becb44ea071f5e1fa1f5d4071dc8788b18c)

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@...el.com>
| Reported-by: Julia Lawall <julia.lawall@...ia.fr>
| Closes: https://lore.kernel.org/r/202401210007.174n0NM0-lkp@intel.com/

cocci warnings: (new ones prefixed by >>)
>> drivers/clk/rockchip/clk-pll.c:912:2-8: WARNING: do_div() does a 64-by-32 division, please consider using div64_u64 instead.

vim +912 drivers/clk/rockchip/clk-pll.c

8f6594494b1cb0 Elaine Zhang 2022-10-18  895
8f6594494b1cb0 Elaine Zhang 2022-10-18  896  static unsigned long rockchip_rk3588_pll_recalc_rate(struct clk_hw *hw, unsigned long prate)
8f6594494b1cb0 Elaine Zhang 2022-10-18  897  {
8f6594494b1cb0 Elaine Zhang 2022-10-18  898  	struct rockchip_clk_pll *pll = to_rockchip_clk_pll(hw);
8f6594494b1cb0 Elaine Zhang 2022-10-18  899  	struct rockchip_pll_rate_table cur;
8f6594494b1cb0 Elaine Zhang 2022-10-18  900  	u64 rate64 = prate, postdiv;
8f6594494b1cb0 Elaine Zhang 2022-10-18  901
8f6594494b1cb0 Elaine Zhang 2022-10-18  902  	rockchip_rk3588_pll_get_params(pll, &cur);
8f6594494b1cb0 Elaine Zhang 2022-10-18  903
8f6594494b1cb0 Elaine Zhang 2022-10-18  904  	rate64 *= cur.m;
8f6594494b1cb0 Elaine Zhang 2022-10-18  905  	do_div(rate64, cur.p);
8f6594494b1cb0 Elaine Zhang 2022-10-18  906
8f6594494b1cb0 Elaine Zhang 2022-10-18  907  	if (cur.k) {
8f6594494b1cb0 Elaine Zhang 2022-10-18  908  		/* fractional mode */
8f6594494b1cb0 Elaine Zhang 2022-10-18  909  		u64 frac_rate64 = prate * cur.k;
8f6594494b1cb0 Elaine Zhang 2022-10-18  910
8f6594494b1cb0 Elaine Zhang 2022-10-18  911  		postdiv = cur.p * 65535;
8f6594494b1cb0 Elaine Zhang 2022-10-18 @912  		do_div(frac_rate64, postdiv);
8f6594494b1cb0 Elaine Zhang 2022-10-18  913  		rate64 += frac_rate64;
8f6594494b1cb0 Elaine Zhang 2022-10-18  914  	}
8f6594494b1cb0 Elaine Zhang 2022-10-18  915  	rate64 = rate64 >> cur.s;
8f6594494b1cb0 Elaine Zhang 2022-10-18  916
8f6594494b1cb0 Elaine Zhang 2022-10-18  917  	return (unsigned long)rate64;
8f6594494b1cb0 Elaine Zhang 2022-10-18  918  }
8f6594494b1cb0 Elaine Zhang 2022-10-18  919

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki