| Message ID | 20211230093610.28012-1-miles.chen@mediatek.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v3] drm/mediatek: Fix unused-but-set variable warning | expand |
On 30/12/2021 10:36, Miles Chen wrote: > clang reports a unused-but-set variable warning: > drivers/gpu/drm/mediatek/mtk_cec.c:85:6: warning: variable 'tmp' set but not used [-Wunused-but-set-variable] > > In current implementation, mtk_cec_mask() writes val into target register > and ignores the mask. After talking to our hdmi experts, mtk_cec_mask() > should read a register, clean only mask bits, and update (val | mask) bits > to the register. > > Fixes: 8f83f26891e1 ("drm/mediatek: Add HDMI support") > > Cc: Zhiqiang Lin <zhiqiang.lin@mediatek.com> > Cc: CK Hu <ck.hu@mediatek.com> > Cc: Matthias Brugger <matthias.bgg@gmail.com> > > Signed-off-by: Miles Chen <miles.chen@mediatek.com> I'm still not happy with the commit subject, I think it is misleading. Clang only helped to find the bug, but the we are fixing something else, that's not just a clang warning. But I don't want to nit-pick too much so: Reviewed-by: Matthias Brugger <matthias.bgg@gmail.com> > > --- > > Change since v1: > add Fixes tag > > Change since v2: > add explanation of mtk_cec_mask() > > Change-Id: Iec6402b0532942f4d0e8bc56817eb87b95c03fad > --- > drivers/gpu/drm/mediatek/mtk_cec.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/mediatek/mtk_cec.c b/drivers/gpu/drm/mediatek/mtk_cec.c > index e9cef5c0c8f7..cdfa648910b2 100644 > --- a/drivers/gpu/drm/mediatek/mtk_cec.c > +++ b/drivers/gpu/drm/mediatek/mtk_cec.c > @@ -85,7 +85,7 @@ static void mtk_cec_mask(struct mtk_cec *cec, unsigned int offset, > u32 tmp = readl(cec->regs + offset) & ~mask; > > tmp |= val & mask; > - writel(val, cec->regs + offset); > + writel(tmp, cec->regs + offset); > } > > void mtk_cec_set_hpd_event(struct device *dev, >
diff --git a/drivers/gpu/drm/mediatek/mtk_cec.c b/drivers/gpu/drm/mediatek/mtk_cec.c index e9cef5c0c8f7..cdfa648910b2 100644 --- a/drivers/gpu/drm/mediatek/mtk_cec.c +++ b/drivers/gpu/drm/mediatek/mtk_cec.c @@ -85,7 +85,7 @@ static void mtk_cec_mask(struct mtk_cec *cec, unsigned int offset, u32 tmp = readl(cec->regs + offset) & ~mask; tmp |= val & mask; - writel(val, cec->regs + offset); + writel(tmp, cec->regs + offset); } void mtk_cec_set_hpd_event(struct device *dev,
clang reports a unused-but-set variable warning: drivers/gpu/drm/mediatek/mtk_cec.c:85:6: warning: variable 'tmp' set but not used [-Wunused-but-set-variable] In current implementation, mtk_cec_mask() writes val into target register and ignores the mask. After talking to our hdmi experts, mtk_cec_mask() should read a register, clean only mask bits, and update (val | mask) bits to the register. Fixes: 8f83f26891e1 ("drm/mediatek: Add HDMI support") Cc: Zhiqiang Lin <zhiqiang.lin@mediatek.com> Cc: CK Hu <ck.hu@mediatek.com> Cc: Matthias Brugger <matthias.bgg@gmail.com> Signed-off-by: Miles Chen <miles.chen@mediatek.com> --- Change since v1: add Fixes tag Change since v2: add explanation of mtk_cec_mask() Change-Id: Iec6402b0532942f4d0e8bc56817eb87b95c03fad --- drivers/gpu/drm/mediatek/mtk_cec.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)