Re: [spacemit:for-next 4/6] drivers/clk/spacemit/ccu-k1.c:241:1: error: initializer element is not a compile-time constant

[Haylen Chu <heylenay@4d2.org>]

On Tue, Apr 15, 2025 at 02:31:37PM +0000, Yixun Lan wrote:
> Hi Alex,
> 
> On 09:16 Tue 15 Apr     , Alex Elder wrote:
> > On 4/15/25 8:44 AM, kernel test robot wrote:
> > > tree:   https://github.com/spacemit-com/linux for-next
> > > head:   9ead3efbc88a21e9a1f38948cc0902518022a2e5
> > > commit: e2d238ba301f25a5c8a7d490a36f9cd014d7aecc [4/6] clk: spacemit: Add clock support for SpacemiT K1 SoC
> > > config: s390-allmodconfig (https://download.01.org/0day-ci/archive/20250415/202504152107.7ekGPIrF-lkp@intel.com/config)
> > > compiler: clang version 18.1.8 (https://github.com/llvm/llvm-project 3b5b5c1ec4a3095ab096dd780e84d7ab81f3d7ff)
> > > reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250415/202504152107.7ekGPIrF-lkp@intel.com/reproduce)
> > > 
> > > 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@intel.com>
> > > | Closes: https://lore.kernel.org/oe-kbuild-all/202504152107.7ekGPIrF-lkp@intel.com/
> > > 
> > > All errors (new ones prefixed by >>):
> > 
> > If I'm interpreting this right, this seems to be a problem on
> > a S390 build (under COMPILE_TEST), because there is no constant
> > version of the __ffs() for that architecture.  This might be the
> > case on other architectures as well.
> > 
> > On RISC-V, this is fine.
> > 
> > Any recommendations on how to address this?
> > 
> it occur to me the __ffs() isn't really necessary, since all input
> is constant value (GENMASK here), we then should know the shift..

I'll second this: instead of calculating the LSB from bitmask in
compilation time, we could derive bitmask from LSB/MSB of the field:
taking slow_uart2_48 as example, this means changing current definition
to

	CCU_DDN_DEFINE(slow_uart2_48, pll1_d4_614p4, MPMU_SUCCR_1,
		       28, 16, 12, 0, 0);

> > 
> > 
> > > 
> > >>> drivers/clk/spacemit/ccu-k1.c:241:1: error: initializer element is not a compile-time constant
> > >       241 | CCU_DDN_DEFINE(slow_uart1_14p74, pll1_d16_153p6, MPMU_SUCCR, GENMASK(28, 16), GENMASK(12, 0), 0);
> > >           | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > >     drivers/clk/spacemit/ccu_ddn.h:33:15: note: expanded from macro 'CCU_DDN_DEFINE'
> > >        33 |         .num_shift      = __ffs(_num_mask),                                     \
> > >           |                           ^~~~~~~~~~~~~~~~
> > >     drivers/clk/spacemit/ccu-k1.c:242:1: error: initializer element is not a compile-time constant
> > >       242 | CCU_DDN_DEFINE(slow_uart2_48, pll1_d4_614p4, MPMU_SUCCR_1, GENMASK(28, 16), GENMASK(12, 0), 0);
> > >           | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > >     drivers/clk/spacemit/ccu_ddn.h:33:15: note: expanded from macro 'CCU_DDN_DEFINE'
> > >        33 |         .num_shift      = __ffs(_num_mask),                                     \
> > >           |                           ^~~~~~~~~~~~~~~~
> > >     2 errors generated.
> > > 
> > > 
> > > vim +241 drivers/clk/spacemit/ccu-k1.c
> > > 
> > >     239	
> > >     240	CCU_GATE_DEFINE(slow_uart, CCU_PARENT_NAME(osc), MPMU_ACGR, BIT(1), CLK_IGNORE_UNUSED);
> > >   > 241	CCU_DDN_DEFINE(slow_uart1_14p74, pll1_d16_153p6, MPMU_SUCCR, GENMASK(28, 16), GENMASK(12, 0), 0);
> > >     242	CCU_DDN_DEFINE(slow_uart2_48, pll1_d4_614p4, MPMU_SUCCR_1, GENMASK(28, 16), GENMASK(12, 0), 0);
> > >     243	
> > > 
> > 
> 
> -- 
> Yixun Lan (dlan)
> Gentoo Linux Developer
> GPG Key ID AABEFD55

Regards,
Haylen Chu