Re: [PATCH v6 1/3] phy: mediatek: fix build warning caused by clang

Chunfeng Yun (云春峰)
2023-01-16T07:37:08Z

On Fri, 2023-01-13 at 23:42 +0530, Vinod Koul wrote:
> On 04-01-23, 21:26, Chunfeng Yun wrote:
> > Remove the temporary @mask_, this may cause build warning when use
> > clang
> > compiler for powerpc, but can't reproduce it when compile for
> > arm64.
> > the build warning is -Wtautological-constant-out-of-range-compare,
> > and
> > caused by
> > "BUILD_BUG_ON_MSG(__bf_cast_unsigned(_mask, _mask)"
> >
> > After removing @mask_, there is a "CHECK:MACRO_ARG_REUSE" when run
> > checkpatch.pl, due to @mask is constant, no reuse problem will
> > happen.
> >
> > Fixes: 84513eccd678 ("phy: mediatek: fix build warning of
> > FIELD_PREP()")
> > Reported-by: kernel test robot <lkp@intel.com>
> > Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
> > ---
> > v6: modify the title
>
> Title still does not tell what this patch is.. It tells me effect of
> the
> patch but not the changes, pls revise...
>
> "remove temp mask" can be better title
Got it, will modify it in next version, thanks

>
> > v5: no changes
> > v4 new patch, I'm not sure it can fix build warning, due to I don't
> > cross compile
> > it for powerpc using clang in office.
> > ---
> > drivers/phy/mediatek/phy-mtk-io.h | 4 ++--
> > 1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/phy/mediatek/phy-mtk-io.h
> > b/drivers/phy/mediatek/phy-mtk-io.h
> > index d20ad5e5be81..58f06db822cb 100644
> > --- a/drivers/phy/mediatek/phy-mtk-io.h
> > +++ b/drivers/phy/mediatek/phy-mtk-io.h
> > @@ -39,8 +39,8 @@ static inline void mtk_phy_update_bits(void
> > __iomem *reg, u32 mask, u32 val)
> > /* field @mask shall be constant and continuous */
> > #define mtk_phy_update_field(reg, mask, val) \
> > ({ \
> > - typeof(mask) mask_ = (mask); \
> > - mtk_phy_update_bits(reg, mask_, FIELD_PREP(mask_, val)); \
> > + BUILD_BUG_ON_MSG(!__builtin_constant_p(mask), "mask is not
> > constant"); \
> > + mtk_phy_update_bits(reg, mask, FIELD_PREP(mask, val)); \
> > })
> >
> > #endif
> > --
> > 2.18.0