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Date:   Mon, 17 Apr 2023 08:30:59 +0300
From:   Laurent Pinchart <laurent.pinchart@ideasonboard.com>
To:     Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Cc:     Manivannan Sadhasivam <mani@kernel.org>,
        Mauro Carvalho Chehab <mchehab@kernel.org>,
        Sakari Ailus <sakari.ailus@linux.intel.com>,
        linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org,
        linux-media@vger.kernel.org
Subject: Re: [PATCH] media: i2c: imx296: Fix error handling while reading
 temperature
Message-ID: <20230417053059.GC28551@pendragon.ideasonboard.com>
References: <827f94730c85b742f9ae66209b383a50ca79ec43.1681683246.git.christophe.jaillet@wanadoo.fr>
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In-Reply-To: <827f94730c85b742f9ae66209b383a50ca79ec43.1681683246.git.christophe.jaillet@wanadoo.fr>
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Hi Christophe,

Thank you for the patch.

On Mon, Apr 17, 2023 at 12:14:42AM +0200, Christophe JAILLET wrote:
> If imx296_read() returns an error, its returned value is a negative value.
> But because of the "& IMX296_TMDOUT_MASK" (i.e. 0x3ff), 'tmdout' can't be
> negative.
> 
> So the error handling does not work as expected and a wrong value is used
> to compute the temperature.
> 
> Apply the IMX296_TMDOUT_MASK mask after checking for errors to fix it.
> 
> Fixes: cb33db2b6ccf ("media: i2c: IMX296 camera sensor driver")
> Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>

Dan Carpenter has submitted the same fix in
https://lore.kernel.org/linux-media/Y%2FYf19AE78jn5YW7@kili/. Sakari,
could you please pick it up ?

> ---
>  drivers/media/i2c/imx296.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/media/i2c/imx296.c b/drivers/media/i2c/imx296.c
> index 4f22c0515ef8..c3d6d52fc772 100644
> --- a/drivers/media/i2c/imx296.c
> +++ b/drivers/media/i2c/imx296.c
> @@ -922,10 +922,12 @@ static int imx296_read_temperature(struct imx296 *sensor, int *temp)
>  	if (ret < 0)
>  		return ret;
>  
> -	tmdout = imx296_read(sensor, IMX296_TMDOUT) & IMX296_TMDOUT_MASK;
> +	tmdout = imx296_read(sensor, IMX296_TMDOUT);
>  	if (tmdout < 0)
>  		return tmdout;
>  
> +	tmdout &= IMX296_TMDOUT_MASK;
> +
>  	/* T(°C) = 246.312 - 0.304 * TMDOUT */;
>  	*temp = 246312 - 304 * tmdout;
>  

-- 
Regards,

Laurent Pinchart