Subject: [PATCH 2/3] hwmon: Driver for OMAP3 temperature sensor

From: [email-masked] (Pavel Machek)
Date: Sun, 18 Jan 2015 21:33:46 +0100

On Wed 2015-01-07 08:19:44, Guenter Roeck wrote:
> On Sat, Jan 03, 2015 at 10:18:58AM +0100, Pavel Machek wrote:
> > On Mon 2014-12-29 11:04:48, Guenter Roeck wrote:
> > > On Mon, Dec 29, 2014 at 07:15:56PM +0100, Pavel Machek wrote:
> > > > On Mon 2014-12-29 12:01:03, Nishanth Menon wrote:
> > > > > On Mon, Dec 29, 2014 at 11:52 AM, Grazvydas Ignotas <[email-masked]> wrote:
> > > > > > On Fri, Dec 26, 2014 at 2:34 PM, Sebastian Reichel <[email-masked]> wrote:
> > > > > >> OMAP34xx and OMAP36xx processors contain a register in the syscon area,
> > > > > >> which can be used to determine the SoCs temperature. This patch provides
> > > > > >> a DT based driver for the temperature sensor based on an older driver
> > > > > >> written by Peter De Schrijver for the Nokia N900 and N9.
> > > > > >
> > > > > > The sensor looks like an earlier iteration of sensors used in newer
> > > > > > OMAPs, which are already supported by maybe
> > > > > > drivers/thermal/ti-soc-thermal/ , maybe it would make sense to update
> > > > > > that driver instead?
> > > > > 
> > > > > Just to be clear - OMAP4 is the first time that the sensors were
> > > > > reliable enough to be used.
> > > > 
> > > > When testing initial version of the patch, they seem to work very well
> > > > in the omap3 case.
> > > > 
> > > Pavel,
> > > 
> > > can you look into the omap4 thermal driver to see if it can be used ?
> > 
> > After some fixes... yes, it seems to be same hardware.
> > 
> So this should be the way to go, but then we have others claim that
> it should not be done because the OMAP3 sensors are too unreliable
> to use for thermal decisions. Not really sure where that leaves us.
> I am kind of opposed to have similar drivers for similar chips
> in two different subsystems.
> 
> Is it possible to add the patch below to the omap thermal driver
> and not use it for thermal decisions ?

Well... noone forces you to enable the driver, and I don't think it
will do any thermal decisions on N900 as it is ... so we should be ok.

Plus, it seems to work reasonably well (say +- 5 C), so situation does
not seem to be as bad as TI claims.

Nokia was actually using it in production.

Best regards,
									Pavel
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