From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wei Ni Subject: Re: [PATCHv9 02/20] thermal: introduce device tree parser Date: Tue, 7 Jan 2014 10:44:10 +0800 Message-ID: <52CB69FA.9080903@nvidia.com> References: <1384285582-16933-1-git-send-email-eduardo.valentin@ti.com> <1384285582-16933-3-git-send-email-eduardo.valentin@ti.com> <52C4D612.2090808@nvidia.com> <52C5A6CE.5060904@nvidia.com> <20140106135145.GD21906@e106331-lin.cambridge.arm.com> <52CAC3AF.9020401@ti.com> Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <52CAC3AF.9020401@ti.com> Sender: linux-pm-owner@vger.kernel.org To: Eduardo Valentin , Mark Rutland Cc: Matthew Longnecker , "swarren@wwwdotorg.org" , Pawel Moll , "ian.campbell@citrix.com" , "rob.herring@calxeda.com" , "linux@roeck-us.net" , "rui.zhang@intel.com" , "grant.likely@linaro.org" , "durgadoss.r@intel.com" , "linux-pm@vger.kernel.org" , "devicetree@vger.kernel.org" , "lm-sensors@lm-sensors.org" , "linux-kernel@vger.kernel.org" List-Id: devicetree@vger.kernel.org On 01/06/2014 10:54 PM, Eduardo Valentin wrote: > * PGP Signed by an unknown key > > On 06-01-2014 09:51, Mark Rutland wrote: >> On Thu, Jan 02, 2014 at 05:50:06PM +0000, Matthew Longnecker wrote: >>> >>>> I think the platform driver may set governor for the thermal zone, >>>> so how about to add a property named as "governor", >>>> and parse it to tzp->governor_name, >>>> something like: >>>> ret = of_property_read_string(child, "governor", &str); >>>> if (ret == 0) >>>> if (strlen(str) < THERMAL_NAME_LENGTH) >>>> strcpy(tzp->governor_name, str); >>>> >>>> Thanks. >>>> Wei. >>> >>> DT is supposed to describe the hardware, right? The governor isn't >>> hardware -- it's a software control policy. On the other hand, that >>> control policy must be tuned according to the behaviors of the platform >>> hardware otherwise the system will be unstable. >>> >>> Is it appropriate to be naming the governor in DT? If so, is it equally >>> appropriate to describe any governor-specific parameters in DT (even >>> though they are pure software constructs)? >> >> The dt should be relatively static -- if the hardware doesn't change the >> dt shouldn't have to. >> >> The governers are not static. We can introduce new ones and throw away >> old ones at any time. Tuning parameters can also change at any time. >> >> I'd prefer to not have governer details described in the dt, and the >> choice of governer and configuration of its tuning parameters should be >> made at runtime somehow. > > Agreed. Yes, I think so, but the of-thermal driver handle the thermal_zone_device_register, and pass the "tzp" without governor_name, so the created thermal_zone's governor will be NULL, then it can't run into the governor->throttle() if needed. And currently there have no interface to support updating governor and configuration at runtime. I think it's better to initialize the governor_name when register the thermal zone device in the of-thermal driver. Thanks. > >> >> Thanks, >> Mark. >> >> > >