Re: [PATCH 2/6] media: i2c: mt9p031: Rewrite a bitwise mask

Laurent Pinchart
2026-04-28T13:25:27Z

On Tue, Apr 28, 2026 at 12:41:08PM +0000, Ricardo Ribalda wrote:
> The current code makes smatch a bit uncomfortable:
> drivers/media/i2c/mt9p031.c:799 mt9p031_s_ctrl() warn: assigning (-1952) to unsigned variable 'data'
>
> Probably because smatch is not clever enough (yet). Do a simple rewrite
> to make sure that smatch understands what we are doing here.
>
> Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
> ---
> drivers/media/i2c/mt9p031.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/media/i2c/mt9p031.c b/drivers/media/i2c/mt9p031.c
> index ea5d43d925ff..5c9dff030b4d 100644
> --- a/drivers/media/i2c/mt9p031.c
> +++ b/drivers/media/i2c/mt9p031.c
> @@ -795,7 +795,7 @@ static int mt9p031_s_ctrl(struct v4l2_ctrl *ctrl)
> ctrl->val &= ~1;
> data = (1 << 6) | (ctrl->val >> 1);
> } else {
> - ctrl->val &= ~7;
> + ctrl->val -= ctrl->val % 8;

This is less readable than it was :-/ Is there a way to avoid the
warning while keeping the ~7 ? Maybe by assigning

data = (ctrl->val - 64) >> 3;
data = (data << 8) | (1 << 6) | 32;

> data = ((ctrl->val - 64) << 5) | (1 << 6) | 32;
> }
>

--
Regards,

Laurent Pinchart