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From: Andy Lutomirski <luto-kltTT9wpgjJwATOyAt5JVQ@public.gmane.org>
To: Guenter Roeck <linux-0h96xk9xTtrk1uMJSBkQmQ@public.gmane.org>
Cc: lm-sensors-GZX6beZjE8VD60Wz+7aTrA@public.gmane.org,
	linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	Jean Delvare <khali-PUYAD+kWke1g9hUCZPvPmw@public.gmane.org>,
	James Ralston
	<james.d.ralston-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>,
	Andras BALI <drewie-Y8qEzhMunLyT9ig0jae3mg@public.gmane.org>
Subject: Re: [PATCH v3 3/4] tsod: New hwmon driver for Temperature Sensors on DIMM
Date: Wed, 17 Jul 2013 15:49:24 -0700	[thread overview]
Message-ID: <CALCETrWQF6p+DveuOxfMhp0r_CrvF=+FOmvfkF-TQ2NVgJ_2aA@mail.gmail.com> (raw)
In-Reply-To: <20130717221902.GC990-0h96xk9xTtrk1uMJSBkQmQ@public.gmane.org>

On Wed, Jul 17, 2013 at 3:19 PM, Guenter Roeck <linux-0h96xk9xTtrk1uMJSBkQmQ@public.gmane.org> wrote:
> On Wed, Jul 17, 2013 at 01:53:07PM -0700, Andy Lutomirski wrote:
>> Signed-off-by: Andy Lutomirski <luto-kltTT9wpgjJwATOyAt5JVQ@public.gmane.org>
>> ---
>
> Why don't you just use the existing jc42 driver ?

Failure to notice it.  *sigh*.  I assumed that any driver for this
device would have "tsod" or "TSOD" somewhere greppable.  I'll at least
send a patch to improve the description.

That being said, the jc42 driver *writes*.  The iMC controller
(AFAICS) uses the data from the TSOD for things like dynamically
adjusting the DRAM refresh interval and IMO the kernel has no business
at all writing to any registers on the TSOD on this platform.  (FWIW,
I tried fiddling with the critical threshold and my box didn't blow up
or report thermal trip events.  But still, this scares me a bit.)

If I modify the i2c_imc driver to add .class = I2C_CLASS_SPD and get
rid of the TSOD probing and load the jc42 module, then it can't
actually find my TSODs (because the i2c core isn't capable of probing
on the iMC bus).  If I manually add the device, it works.

But I'd like to keep the enumeration code I wrote around, since the
main point of this exercise is to enumerate things that aren't
actually hwmon devices.  But I don't want random sensors scripts
reprogramming the hardware.  Is the some magic I can work (or should
add) with i2c_board_info to force the jc42 driver into a read-only
mode?

In any case, am I doing the right thing by not setting I2C_CLASS_SPD on my bus?

--Andy

WARNING: multiple messages have this Message-ID (diff)
From: Andy Lutomirski <luto@amacapital.net>
To: Guenter Roeck <linux-0h96xk9xTtrk1uMJSBkQmQ@public.gmane.org>
Cc: lm-sensors-GZX6beZjE8VD60Wz+7aTrA@public.gmane.org,
	linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	Jean Delvare <khali-PUYAD+kWke1g9hUCZPvPmw@public.gmane.org>,
	James Ralston
	<james.d.ralston-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>,
	Andras BALI <drewie-Y8qEzhMunLyT9ig0jae3mg@public.gmane.org>
Subject: Re: [lm-sensors] [PATCH v3 3/4] tsod: New hwmon driver for Temperature Sensors on DIMM
Date: Wed, 17 Jul 2013 22:49:24 +0000	[thread overview]
Message-ID: <CALCETrWQF6p+DveuOxfMhp0r_CrvF=+FOmvfkF-TQ2NVgJ_2aA@mail.gmail.com> (raw)
In-Reply-To: <20130717221902.GC990-0h96xk9xTtrk1uMJSBkQmQ@public.gmane.org>

On Wed, Jul 17, 2013 at 3:19 PM, Guenter Roeck <linux@roeck-us.net> wrote:
> On Wed, Jul 17, 2013 at 01:53:07PM -0700, Andy Lutomirski wrote:
>> Signed-off-by: Andy Lutomirski <luto@amacapital.net>
>> ---
>
> Why don't you just use the existing jc42 driver ?

Failure to notice it.  *sigh*.  I assumed that any driver for this
device would have "tsod" or "TSOD" somewhere greppable.  I'll at least
send a patch to improve the description.

That being said, the jc42 driver *writes*.  The iMC controller
(AFAICS) uses the data from the TSOD for things like dynamically
adjusting the DRAM refresh interval and IMO the kernel has no business
at all writing to any registers on the TSOD on this platform.  (FWIW,
I tried fiddling with the critical threshold and my box didn't blow up
or report thermal trip events.  But still, this scares me a bit.)

If I modify the i2c_imc driver to add .class = I2C_CLASS_SPD and get
rid of the TSOD probing and load the jc42 module, then it can't
actually find my TSODs (because the i2c core isn't capable of probing
on the iMC bus).  If I manually add the device, it works.

But I'd like to keep the enumeration code I wrote around, since the
main point of this exercise is to enumerate things that aren't
actually hwmon devices.  But I don't want random sensors scripts
reprogramming the hardware.  Is the some magic I can work (or should
add) with i2c_board_info to force the jc42 driver into a read-only
mode?

In any case, am I doing the right thing by not setting I2C_CLASS_SPD on my bus?

--Andy

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lm-sensors@lm-sensors.org
http://lists.lm-sensors.org/mailman/listinfo/lm-sensors

  parent reply	other threads:[~2013-07-17 22:49 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-07-17 20:53 [PATCH v3 0/4] iMC SMBUS, TSOD hwmon devices, and eeprom modalias Andy Lutomirski
2013-07-17 20:53 ` [lm-sensors] " Andy Lutomirski
     [not found] ` <cover.1374093761.git.luto-kltTT9wpgjJwATOyAt5JVQ@public.gmane.org>
2013-07-17 20:53   ` [PATCH v3 1/4] i2c: Add DIMM bus code Andy Lutomirski
2013-07-17 20:53     ` [lm-sensors] " Andy Lutomirski
     [not found]     ` <b8e50b55358b4f0cd1db96174a9e6a2e69780359.1374093761.git.luto-kltTT9wpgjJwATOyAt5JVQ@public.gmane.org>
2013-07-17 22:23       ` Guenter Roeck
2013-07-17 22:23         ` [lm-sensors] " Guenter Roeck
     [not found]         ` <20130717222349.GD990-0h96xk9xTtrk1uMJSBkQmQ@public.gmane.org>
2013-07-17 23:04           ` Andy Lutomirski
2013-07-17 23:04             ` [lm-sensors] " Andy Lutomirski
     [not found]             ` <CALCETrVCotmG2PCQUF1BaAcbvnysMbS-kE4SJHoSokgzaML0jg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2013-07-18  0:57               ` Andy Lutomirski
2013-07-18  0:57                 ` [lm-sensors] " Andy Lutomirski
2013-07-17 20:53   ` [PATCH v3 2/4] i2c_imc: New driver for Intel's iMC, found on LGA2011 chips Andy Lutomirski
2013-07-17 20:53     ` [lm-sensors] " Andy Lutomirski
2013-07-17 20:53   ` [PATCH v3 3/4] tsod: New hwmon driver for Temperature Sensors on DIMM Andy Lutomirski
2013-07-17 20:53     ` [lm-sensors] " Andy Lutomirski
     [not found]     ` <f358329ff1dd3c3c272cadb4a358a5587cb28e18.1374093761.git.luto-kltTT9wpgjJwATOyAt5JVQ@public.gmane.org>
2013-07-17 22:19       ` Guenter Roeck
2013-07-17 22:19         ` [lm-sensors] " Guenter Roeck
     [not found]         ` <20130717221902.GC990-0h96xk9xTtrk1uMJSBkQmQ@public.gmane.org>
2013-07-17 22:49           ` Andy Lutomirski [this message]
2013-07-17 22:49             ` Andy Lutomirski
     [not found]             ` <CALCETrWQF6p+DveuOxfMhp0r_CrvF=+FOmvfkF-TQ2NVgJ_2aA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2013-07-17 23:09               ` Guenter Roeck
2013-07-17 23:09                 ` [lm-sensors] " Guenter Roeck
     [not found]                 ` <20130717230909.GB2120-0h96xk9xTtrk1uMJSBkQmQ@public.gmane.org>
2013-07-17 23:13                   ` Andy Lutomirski
2013-07-17 23:13                     ` [lm-sensors] " Andy Lutomirski
2013-07-17 20:53   ` [PATCH v3 4/4] eeprom: Add a MODULE_DEVICE_TABLE Andy Lutomirski
2013-07-17 20:53     ` [lm-sensors] " Andy Lutomirski
     [not found]     ` <5661ebb4676a4d20678f369df3a2da5d587e9100.1374093761.git.luto-kltTT9wpgjJwATOyAt5JVQ@public.gmane.org>
2013-07-18  7:11       ` Jean Delvare
2013-07-18  7:11         ` [lm-sensors] " Jean Delvare
     [not found]         ` <20130718091116.6757e088-R0o5gVi9kd7kN2dkZ6Wm7A@public.gmane.org>
2013-07-18 16:15           ` Andy Lutomirski
2013-07-18 16:15             ` [lm-sensors] " Andy Lutomirski
     [not found]             ` <CALCETrX9Et-D+C9qJ9Ou46UyuWdqD6SN+PSu6RKDwnVogE=jZQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2013-07-18 20:31               ` Jean Delvare
2013-07-18 20:31                 ` [lm-sensors] " Jean Delvare
     [not found]                 ` <20130718223125.63e03635-R0o5gVi9kd7kN2dkZ6Wm7A@public.gmane.org>
2013-07-18 20:44                   ` Andy Lutomirski
2013-07-18 20:44                     ` [lm-sensors] " Andy Lutomirski

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