linux-kernel - Re: [PATCH] iio: imu: inv_icm42600: Fix temperature calculation

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID:
 <FR3P281MB175785C1AA53950D27EE3C03CE8F2@FR3P281MB1757.DEUP281.PROD.OUTLOOK.COM>
Date: Sun, 4 May 2025 16:46:00 +0000
From: Jean-Baptiste Maneyrol <Jean-Baptiste.Maneyrol@....com>
To: Jonathan Cameron <jic23@...nel.org>, Sean Nyekjaer <sean@...nix.com>
CC: Lars-Peter Clausen <lars@...afoo.de>,
        Jonathan Cameron
	<Jonathan.Cameron@...wei.com>,
        "linux-iio@...r.kernel.org"
	<linux-iio@...r.kernel.org>,
        "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] iio: imu: inv_icm42600: Fix temperature calculation

Hello Sean, Jonathan,

good catch indeed!
This is all good for me, thanks for your fix.

Acked-by: Jean-Baptiste Maneyrol <jean-baptiste.maneyrol@....com>

Best regards,
JB

________________________________________
From: Jonathan Cameron <jic23@...nel.org>
Sent: Sunday, May 4, 2025 17:28
To: Sean Nyekjaer <sean@...nix.com>
Cc: Jean-Baptiste Maneyrol <Jean-Baptiste.Maneyrol@....com>; Lars-Peter Clausen <lars@...afoo.de>; Jean-Baptiste Maneyrol <Jean-Baptiste.Maneyrol@....com>; Jonathan Cameron <Jonathan.Cameron@...wei.com>; linux-iio@...r.kernel.org <linux-iio@...r.kernel.org>; linux-kernel@...r.kernel.org <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] iio: imu: inv_icm42600: Fix temperature calculation
 
This Message Is From an External Sender
This message came from outside your organization.
 
On Fri, 02 May 2025 11:37:26 +0200
Sean Nyekjaer <sean@...nix.com> wrote:

> From the documentation:
> "offset to be added to <type>[Y]_raw prior toscaling by <type>[Y]_scale"
> Offset should be applied before multiplying scale, so divide offset by
> scale to make this correct.
> 
> Fixes: bc3eb0207fb5 ("iio: imu: inv_icm42600: add temperature sensor support")
> Signed-off-by: Sean Nyekjaer <sean@...nix.com>
Looks correct to me.  Given this is going to have impacts on userspace
I'd definitely like to know Jean-Baptiste has seen it though before I apply.
So, Jean-Baptiste please take a look!

Thanks,

Jonathan


> ---
>  drivers/iio/imu/inv_icm42600/inv_icm42600_temp.c | 8 +++++---
>  1 file changed, 5 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/iio/imu/inv_icm42600/inv_icm42600_temp.c b/drivers/iio/imu/inv_icm42600/inv_icm42600_temp.c
> index 213cce1c31110e669e7191c8b42c9524c0d3e5db..91f0f381082bda3dbb95dfe1a38adcdc4eaf5419 100644
> --- a/drivers/iio/imu/inv_icm42600/inv_icm42600_temp.c
> +++ b/drivers/iio/imu/inv_icm42600/inv_icm42600_temp.c
> @@ -67,16 +67,18 @@ int inv_icm42600_temp_read_raw(struct iio_dev *indio_dev,
>  		return IIO_VAL_INT;
>  	/*
>  	 * T°C = (temp / 132.48) + 25
> -	 * Tm°C = 1000 * ((temp * 100 / 13248) + 25)
> +	 * Tm°C = 1000 * ((temp / 132.48) + 25)
> +	 * Tm°C = 7.548309 * temp + 25000
> +	 * Tm°C = (temp + 3312) * 7.548309
>  	 * scale: 100000 / 13248 ~= 7.548309
> -	 * offset: 25000
> +	 * offset: 3312
>  	 */
>  	case IIO_CHAN_INFO_SCALE:
>  		*val = 7;
>  		*val2 = 548309;
>  		return IIO_VAL_INT_PLUS_MICRO;
>  	case IIO_CHAN_INFO_OFFSET:
> -		*val = 25000;
> +		*val = 3312;
>  		return IIO_VAL_INT;
>  	default:
>  		return -EINVAL;
> 
> ---
> base-commit: 609bc31eca06c7408e6860d8b46311ebe45c1fef
> change-id: 20250502-imu-edc0faa6dae9
> 
> Best regards,