[lm-sensors] Intend to implement ADT7467/ADT7468 driver

[lm-sensors] Intend to implement ADT7467/ADT7468 driver

[Bernhard Rieder]

Hi Everybody,

I am currently working on an ADT746[78] driver which will be finished soon.

However, I am not sure how to react to errors. Which values do I return in case
the chip reports errors (i.e. temp=-64 is an error value for the temperature reading,
-63 is ok). Are there somewhere error values defined which can used for this? I do
not think usinf -64 is a good choice, because the chip has two modes for temperature
and an error would be reported as -128 in the other mode. Additionally, -64 could be
interpreted as a real value (at least in sibiria when it is a cold winter day).

Are there somewhere constants like SENSORS_VOLTAGE_INVALID, SENSORS_TEMP_INVALID, ...
which I missed? I think common error values would be really beneficial ...

best regards,
Bernhard

-- 
Dipl.-Ing. Bernhard Rieder           email: bernhard@vmars.tuwien.ac.at
Real-Time Systems Group              web: http://www.vmars.tuwien.ac.at/
Vienna University of Technology      voice: +43 (1) 58801-18224
A-1040 Wien, Treitlstrafle 3/182-1    fax:   +43 (1) 5869149


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Re: [lm-sensors] Intend to implement ADT7467/ADT7468 driver

[Hans de Goede]

Bernhard Rieder wrote:
> Hi Everybody,
> 
> I am currently working on an ADT746[78] driver which will be finished soon.
> 
> However, I am not sure how to react to errors. Which values do I return in case
> the chip reports errors (i.e. temp=-64 is an error value for the temperature reading,
> -63 is ok). Are there somewhere error values defined which can used for this? I do
> not think usinf -64 is a good choice, because the chip has two modes for temperature
> and an error would be reported as -128 in the other mode. Additionally, -64 could be
> interpreted as a real value (at least in sibiria when it is a cold winter day).
> 

To report errors we have a separate sysfs attribute called temp#_fault, I think 
you want to implement that and have it return 1 when read when the temp is 
-64/-128 (normally it should read as 0). For temp#_input you can just return 
the temp even if it is an error, apps should ignore the reading from 
temp#_input when temp#_fault reads 1.

Regards,

Hans

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Re: [lm-sensors] Intend to implement ADT7467/ADT7468 driver

[Darrick J. Wong]

On Tue, Oct 21, 2008 at 02:21:46PM +0200, Bernhard Rieder wrote:
> Hi Everybody,
> 
> I am currently working on an ADT746[78] driver which will be finished soon.
> 
> However, I am not sure how to react to errors. Which values do I return in case
> the chip reports errors (i.e. temp=-64 is an error value for the temperature reading,
> -63 is ok). Are there somewhere error values defined which can used for this? I do
> not think usinf -64 is a good choice, because the chip has two modes for temperature
> and an error would be reported as -128 in the other mode. Additionally, -64 could be
> interpreted as a real value (at least in sibiria when it is a cold winter day).
> 
> Are there somewhere constants like SENSORS_VOLTAGE_INVALID, SENSORS_TEMP_INVALID, ...
> which I missed? I think common error values would be really beneficial ...

Hm... I think the lm85/adt7468 have similar registers.  Oddly, I was
working on a patch to the lm85 driver to add 7468 support.  I suspect we
should collaborate. :)

Also, a driver for the adt7467 is (mostly?) implemented in
drivers/macintosh/therm_adt746x.c, though it relies on finding the
device via some sort of openfirmware calls, which isn't appropriate for
PCs.

--D

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Re: [lm-sensors] Intend to implement ADT7467/ADT7468 driver

[Jean Delvare]

On Tue, 21 Oct 2008 15:43:23 -0700, Darrick J. Wong wrote:
> On Tue, Oct 21, 2008 at 02:21:46PM +0200, Bernhard Rieder wrote:
> > Hi Everybody,
> > 
> > I am currently working on an ADT746[78] driver which will be finished soon.
> > 
> > However, I am not sure how to react to errors. Which values do I return in case
> > the chip reports errors (i.e. temp=-64 is an error value for the temperature reading,
> > -63 is ok). Are there somewhere error values defined which can used for this? I do
> > not think usinf -64 is a good choice, because the chip has two modes for temperature
> > and an error would be reported as -128 in the other mode. Additionally, -64 could be
> > interpreted as a real value (at least in sibiria when it is a cold winter day).
> > 
> > Are there somewhere constants like SENSORS_VOLTAGE_INVALID, SENSORS_TEMP_INVALID, ...
> > which I missed? I think common error values would be really beneficial ...
> 
> Hm... I think the lm85/adt7468 have similar registers.  Oddly, I was
> working on a patch to the lm85 driver to add 7468 support.  I suspect we
> should collaborate. :)

The lm85 driver is already pretty big. I'd only add support for chips
which are 100% compatible with an already supported chip to it. If the
ADT7468 and ADT7467 have specific properties (missing or extra inputs,
different scaling factors, extra features...) I'd rather have a new
driver for them (which might as well be derived from lm85.c, but then
please make sure you start from the very last version as I fixed it and
cleaned it up extensively in the past few months.)

> Also, a driver for the adt7467 is (mostly?) implemented in
> drivers/macintosh/therm_adt746x.c, though it relies on finding the
> device via some sort of openfirmware calls, which isn't appropriate for
> PCs.

The macintosh driver also doesn't implement the standard sysfs
interface and I don't think it supports voltage inputs. I could never
convince the powerpc people to drop their custom interface in favor of
ours. Maybe with the advent of new-style I2C drivers and if we
implement an in-kernel interface for temperature value access, they
will reconsider...

-- 
Jean Delvare

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