From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pavel Machek Subject: Re: [PATCH 2/3] hwmon: Driver for OMAP3 temperature sensor Date: Sun, 18 Jan 2015 21:33:46 +0100 Message-ID: <20150118203346.GA29863@amd> References: <20141226102933.GA28778@amd> <1419597294-21487-1-git-send-email-sre@kernel.org> <1419597294-21487-3-git-send-email-sre@kernel.org> <20141229181556.GA26926@amd> <20141229190448.GA27124@roeck-us.net> <20150103091858.GA30538@amd> <20150107161944.GB9012@roeck-us.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20150107161944.GB9012@roeck-us.net> Sender: linux-omap-owner@vger.kernel.org To: Guenter Roeck Cc: Nishanth Menon , Grazvydas Ignotas , Sebastian Reichel , Mark Rutland , dt list , Pawel Moll , Ian Campbell , Tony Lindgren , Kumar Gala , "linux-kernel@vger.kernel.org" , lm-sensors@lm-sensors.org, Rob Herring , Jean Delvare , =?iso-8859-1?Q?Beno=EEt?= Cousson , Pali Rohar , "linux-omap@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" List-Id: devicetree@vger.kernel.org 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 wrote: > > > > > > On Fri, Dec 26, 2014 at 2:34 PM, Sebastian Reichel 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 -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html