Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752444AbaAMVbA (ORCPT ); Mon, 13 Jan 2014 16:31:00 -0500 Received: from comal.ext.ti.com ([198.47.26.152]:54586 "EHLO comal.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752094AbaAMVa5 (ORCPT ); Mon, 13 Jan 2014 16:30:57 -0500 Message-ID: <52D45AC8.1010607@ti.com> Date: Mon, 13 Jan 2014 17:29:44 -0400 From: Eduardo Valentin User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130510 Thunderbird/17.0.6 MIME-Version: 1.0 To: Wei Ni CC: Eduardo Valentin , Mark Rutland , 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" Subject: Re: [PATCHv9 02/20] thermal: introduce device tree parser 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> <52CB69FA.9080903@nvidia.com> In-Reply-To: <52CB69FA.9080903@nvidia.com> X-Enigmail-Version: 1.6 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="BcHIXGgKPN3KOsf4Pahsrt4VtRMfLhVLN" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --BcHIXGgKPN3KOsf4Pahsrt4VtRMfLhVLN Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Wei, On 06-01-2014 22:44, Wei Ni wrote: > 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 =3D of_property_read_string(child, "governor",= &str); >>>>> if (ret =3D=3D 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=20 >>>> hardware -- it's a software control policy. On the other hand, that = >>>> control policy must be tuned according to the behaviors of the platf= orm=20 >>>> hardware otherwise the system will be unstable. >>>> >>>> Is it appropriate to be naming the governor in DT? If so, is it equa= lly=20 >>>> appropriate to describe any governor-specific parameters in DT (even= =20 >>>> 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 awa= y >>> 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. >=20 > Yes, I think so, but the of-thermal driver handle the > thermal_zone_device_register, and pass the "tzp" without governor_name,= In fact, it will fall into the default governor, which is step_wise, by default config. > 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 Actually, no, the tz will be set to default governor, and its throttle call will be called. > 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. Still, why would you need to change the governor from a in kernel decision? There is an ABI to change the thermal zone policy based on user(land) request. If you need to change the policy from within the kernel, which seams to be what you are trying to propose, you need to explain why you need it, say, by giving at least one user of this API or explaining its use case. >=20 > Thanks. >=20 >> >>> >>> Thanks, >>> Mark. >>> >>> >> >> >=20 >=20 >=20 --=20 You have got to be excited about what you are doing. (L. Lamport) Eduardo Valentin --BcHIXGgKPN3KOsf4Pahsrt4VtRMfLhVLN Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (GNU/Linux) Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iF4EAREIAAYFAlLUWsgACgkQCXcVR3XQvP1orAEAialtk3Aps/1oTiWfB2foDt96 3h1Tq5XY7wTnht9Q61cBALCe0wBWAO3KHbJYKNgDeHcMid5INnBMshA76ABfWOtd =F2o/ -----END PGP SIGNATURE----- --BcHIXGgKPN3KOsf4Pahsrt4VtRMfLhVLN-- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/