Re: [PATCH] media: i2c: rdamc21: Fix warning on u8 cast

From: Jacopo Mondi <jacopo@jmondi.org>
To: Jacopo Mondi <jacopo+renesas@jmondi.org>,
	Mauro Carvalho Chehab <mchehab@kernel.org>
Cc: Hans Verkuil <hverkuil@xs4all.nl>,
	linux-media@vger.kernel.org, linux-renesas-soc@vger.kernel.org
Subject: Re: [PATCH] media: i2c: rdamc21: Fix warning on u8 cast
Date: Sat, 13 Feb 2021 09:53:19 +0100	[thread overview]
Message-ID: <20210213085319.e5zrkkgyn5f25yai@uno.localdomain> (raw)
In-Reply-To: <20210208132749.97738-1-jacopo+renesas@jmondi.org>

Hello,

On Mon, Feb 08, 2021 at 02:27:49PM +0100, Jacopo Mondi wrote:
> Sparse reports a warning on a cast to u8 of a 16 bits constant.
>
> drivers/media/i2c/rdacm21.c:348:62: warning: cast truncates bits
> from constant value (300a becomes a)
>
> Even if the behaviour is intended, silence the sparse warning replacing
> the cast with a bitwise & operation.
>
> Fixes: a59f853b3b4b ("media: i2c: Add driver for RDACM21 camera module")
> Reported-by: Hans Verkuil <hverkuil@xs4all.nl>
> Signed-off-by: Jacopo Mondi <jacopo+renesas@jmondi.org>

I don't see this last fix for this window collected in the most recent
media tree.

Is it too late already ? It's really a trivial fix but silences a
sparse warning, so it might be worth collecting it ?

Thanks
   j

> ---
>  drivers/media/i2c/rdacm21.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/media/i2c/rdacm21.c b/drivers/media/i2c/rdacm21.c
> index dcc21515e5a4..179d107f494c 100644
> --- a/drivers/media/i2c/rdacm21.c
> +++ b/drivers/media/i2c/rdacm21.c
> @@ -345,7 +345,7 @@ static int ov10640_initialize(struct rdacm21_device *dev)
>  	/* Read OV10640 ID to test communications. */
>  	ov490_write_reg(dev, OV490_SCCB_SLAVE0_DIR, OV490_SCCB_SLAVE_READ);
>  	ov490_write_reg(dev, OV490_SCCB_SLAVE0_ADDR_HIGH, OV10640_CHIP_ID >> 8);
> -	ov490_write_reg(dev, OV490_SCCB_SLAVE0_ADDR_LOW, (u8)OV10640_CHIP_ID);
> +	ov490_write_reg(dev, OV490_SCCB_SLAVE0_ADDR_LOW, OV10640_CHIP_ID & 0xff);
>
>  	/* Trigger SCCB slave transaction and give it some time to complete. */
>  	ov490_write_reg(dev, OV490_HOST_CMD, OV490_HOST_CMD_TRIGGER);
> --
> 2.30.0
>