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,