From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jean Delvare <khali@linux-fr.org>
Date: Mon, 14 Sep 2009 20:48:46 +0000
Subject: Re: [lm-sensors] [PATCH] hwmon: (adm1031) Add sysfs files for
Message-Id: <20090914224846.5a7fd079@hyperion.delvare>
List-Id: <lm-sensors.vger.kernel.org>
References: <20090630183918.GA3322@ovro.caltech.edu>
In-Reply-To: <20090630183918.GA3322@ovro.caltech.edu>
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To: lm-sensors@vger.kernel.org

Hi Ira,

On Tue, 30 Jun 2009 11:39:18 -0700, Ira Snyder wrote:
> The ADM1030/ADM1031 chips have temperature offset registers, for both the
> local and remote temperature sensors. Following the example set forth in
> the LM90/ADM1032 driver, expose the offset registers to userspace.
>=20
> Signed-off-by: Ira W. Snyder <iws@ovro.caltech.edu>
> ---
>=20
> I have tested this with an adm1031 chip, and I see the offsets as
> expected. I do not have any other compatible chips to test with, however
> I read the adm1030 datasheet, and everything should work fine.
>=20
> On the adm1031, the datasheet claims the offset registers can be used to
> add/subtract 15 degC from the temperature reading. I have found that it
> is actually possible to add 15 degC and subtract 16 degC. Following the
> data sheet, I clamped the value to +- 15 degC, just in case other chips
> are not compatible.
>=20
>  drivers/hwmon/adm1031.c |   40 ++++++++++++++++++++++++++++++++++++++++
>  1 files changed, 40 insertions(+), 0 deletions(-)
>=20
> diff --git a/drivers/hwmon/adm1031.c b/drivers/hwmon/adm1031.c
> index 7894418..5690595 100644
> --- a/drivers/hwmon/adm1031.c
> +++ b/drivers/hwmon/adm1031.c
> @@ -145,6 +147,10 @@ adm1031_write_value(struct i2c_client *client, u8 re=
g, unsigned int value)
> =20
>  #define TEMP_FROM_REG_EXT(val, ext)	(TEMP_FROM_REG(val) + (ext) * 125)
> =20
> +#define TEMP_OFFSET_TO_REG(val)		(TEMP_TO_REG(val) & 0x8f)
> +#define TEMP_OFFSET_FROM_REG(val)	TEMP_FROM_REG((val) < 0 ? \
> +						      (val) | 0x70 : (val))

This is not how I read the datasheet for negative offsets. The ADM1030
datasheet says that -1=B0C would be coded 0x81, while your implementation
would decode 0x81 to -15=B0C. But I admit the datasheet isn't too clear
either... Did you test your code with negative offsets and found that
it works OK?

--=20
Jean Delvare

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