From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_NEOMUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D5277C48BD7 for ; Thu, 27 Jun 2019 18:37:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9D1982075E for ; Thu, 27 Jun 2019 18:37:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1561660676; bh=WtgVWv3h3e6GjUeYM72+oOL3QStDuHufllKTBP4Cqjw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=CponlJ6x6eo9iEVgJtSHaGd0pkrQ/bPsobYR0sft38QfbVULJJWpgWSF8s3UF6njb aR+LNXY1BcV9xsYUEdllVJ3trbzoVna5yOLzGoNR5TToDw/gFPuFQsARlFuujH8wkV bjN10lf1UWF0BSwUY8D4cqMOHv3OfxP/2YcBMR6Y= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726476AbfF0Sh4 (ORCPT ); Thu, 27 Jun 2019 14:37:56 -0400 Received: from mail.kernel.org ([198.145.29.99]:35680 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726384AbfF0Sh4 (ORCPT ); Thu, 27 Jun 2019 14:37:56 -0400 Received: from earth.universe (unknown [185.62.205.103]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 93EC22064A; Thu, 27 Jun 2019 18:37:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1561660675; bh=WtgVWv3h3e6GjUeYM72+oOL3QStDuHufllKTBP4Cqjw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=GblNFDB4+qPQZ2cNTxdiAQ8mhnWmjEhqcOFBbvX5LW7NPvYajqpwl6iBWf6XGGn9Y UEQt+CsfWcbMOSS+teKpMqLOs+HpsGVS23yuUohkkradaXvMtrDPoTDzejSw39uBK7 VjRf4ciUwyl90j95mp7yV/jNna4htgYcUsDgXqHc= Received: by earth.universe (Postfix, from userid 1000) id 4ED403C08D5; Thu, 27 Jun 2019 20:37:52 +0200 (CEST) Date: Thu, 27 Jun 2019 20:37:52 +0200 From: Sebastian Reichel To: Enric Balletbo Serra Cc: Benson Leung , Enric Balletbo i Serra , Linux PM list , Sameer Nanda , Benson Leung , "Rafael J. Wysocki" , Gwendal Grignou , linux-kernel , Len Brown , Guenter Roeck , Adam.Thomson.Opensource@diasemi.com, Collabora Kernel ML , Pavel Machek Subject: Re: [PATCH v4 1/2] power: supply: add input power and voltage limit properties Message-ID: <20190627183752.4amfttcvd7bswom6@earth.universe> References: <20190507095248.17915-1-enric.balletbo@collabora.com> <20190523195438.GA110498@google.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="e4ghregrusiggzmz" Content-Disposition: inline In-Reply-To: User-Agent: NeoMutt/20180716 Sender: linux-pm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org --e4ghregrusiggzmz Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Hi, I just queued both patches. Thanks for the detailed description and documentation. -- Sebastian On Tue, Jun 25, 2019 at 12:04:13PM +0200, Enric Balletbo Serra wrote: > Hi Sebastian, Pavel, >=20 > Missatge de Benson Leung del dia dj., 23 de maig > 2019 a les 21:55: > > > > Hi Enric, > > > > On Tue, May 07, 2019 at 11:52:47AM +0200, Enric Balletbo i Serra wrote: > > > For thermal management strategy you might be interested on limit the > > > input power for a power supply. We already have current limit but > > > basically what we probably want is to limit power. So, introduce the > > > input_power_limit property. > > > > > > Although the common use case is limit the input power, in some > > > specific cases it is the voltage that is problematic (i.e some regula= tors > > > have different efficiencies at higher voltage resulting in more heat). > > > So introduce also the input_voltage_limit property. > > > > > > This happens in one Chromebook and is used on the Pixel C's thermal > > > management strategy to effectively limit the input power to 5V 3A when > > > the screen is on. When the screen is on, the display, the CPU, and th= e GPU > > > all contribute more heat to the system than while the screen is off, = and > > > we made a tradeoff to throttle the charger in order to give more of t= he > > > thermal budget to those other components. > > > > > > So there's nothing fundamentally broken about the hardware that would > > > cause the Pixel C to malfunction if we were charging at 9V or 12V ins= tead > > > of 5V when the screen is on, i.e. if userspace doesn't change this. > > > > > > What would happen is that you wouldn't meet Google's skin temperature > > > targets on the system if the charger was allowed to run at 9V or 12V = with > > > the screen on. > > > > > > For folks hacking on Pixel Cs (which is now outside of Google's offic= ial > > > support window for Android) and customizing their own kernel and user= space > > > this would be acceptable, but we wanted to expose this feature in the > > > power supply properties because the feature does exist in the Emedded > > > Controller firmware of the Pixel C and all of Google's Chromebooks wi= th > > > USB-C made since 2015 in case someone running an up to date kernel wa= nted > > > to limit the charging power for thermal or other reasons. > > > > > > This patch exposes a new property, similar to input current limit, to > > > re-configure the maximum voltage from the external supply at runtime > > > based on system-level knowledge or user input. > > > > > > Signed-off-by: Enric Balletbo i Serra > > > Reviewed-by: Guenter Roeck > > > Acked-by: Adam Thomson > > > > Reviewed-by: Benson Leung > > >=20 > We're close to the merge window so I'm wondering if there are more > concerns on this patchset? >=20 > Thanks, > ~ Enric >=20 > > > --- > > > > > > Changes in v4: > > > - Add also input_power_limit. > > > > > > Changes in v3: > > > - Improve commit log and documentation with Benson comments. > > > > > > Changes in v2: > > > - Document the new property in ABI/testing/sysfs-class-power. > > > - Add the Reviewed-by Guenter Roeck tag. > > > > > > Documentation/ABI/testing/sysfs-class-power | 32 +++++++++++++++++++= ++ > > > Documentation/power/power_supply_class.txt | 4 +++ > > > drivers/power/supply/power_supply_sysfs.c | 2 ++ > > > include/linux/power_supply.h | 2 ++ > > > 4 files changed, 40 insertions(+) > > > > > > diff --git a/Documentation/ABI/testing/sysfs-class-power b/Documentat= ion/ABI/testing/sysfs-class-power > > > index 5e23e22dce1b..962a27a1daf8 100644 > > > --- a/Documentation/ABI/testing/sysfs-class-power > > > +++ b/Documentation/ABI/testing/sysfs-class-power > > > @@ -331,10 +331,42 @@ Description: > > > supply. Normally this is configured based on the type of > > > connection made (e.g. A configured SDP should output a = maximum > > > of 500mA so the input current limit is set to the same = value). > > > + Use preferably input_power_limit, and for problems that= can be > > > + solved using power limit use input_current_limit. > > > > > > Access: Read, Write > > > Valid values: Represented in microamps > > > > > > +What: /sys/class/power_supply//input_vol= tage_limit > > > +Date: May 2019 > > > +Contact: linux-pm@vger.kernel.org > > > +Description: > > > + This entry configures the incoming VBUS voltage limit c= urrently > > > + set in the supply. Normally this is configured based on > > > + system-level knowledge or user input (e.g. This is part= of the > > > + Pixel C's thermal management strategy to effectively li= mit the > > > + input power to 5V when the screen is on to meet Google'= s skin > > > + temperature targets). Note that this feature should not= be > > > + used for safety critical things. > > > + Use preferably input_power_limit, and for problems that= can be > > > + solved using power limit use input_voltage_limit. > > > + > > > + Access: Read, Write > > > + Valid values: Represented in microvolts > > > + > > > +What: /sys/class/power_supply//input_pow= er_limit > > > +Date: May 2019 > > > +Contact: linux-pm@vger.kernel.org > > > +Description: > > > + This entry configures the incoming power limit currentl= y set > > > + in the supply. Normally this is configured based on > > > + system-level knowledge or user input. Use preferably th= is > > > + feature to limit the incoming power and use current/vol= tage > > > + limit only for problems that can be solved using power = limit. > > > + > > > + Access: Read, Write > > > + Valid values: Represented in microwatts > > > + > > > What: /sys/class/power_supply//online, > > > Date: May 2007 > > > Contact: linux-pm@vger.kernel.org > > > diff --git a/Documentation/power/power_supply_class.txt b/Documentati= on/power/power_supply_class.txt > > > index 300d37896e51..1e3c705111db 100644 > > > --- a/Documentation/power/power_supply_class.txt > > > +++ b/Documentation/power/power_supply_class.txt > > > @@ -137,6 +137,10 @@ power supply object. > > > > > > INPUT_CURRENT_LIMIT - input current limit programmed by charger. Ind= icates > > > the current drawn from a charging source. > > > +INPUT_VOLTAGE_LIMIT - input voltage limit programmed by charger. Ind= icates > > > +the voltage limit from a charging source. > > > +INPUT_POWER_LIMIT - input power limit programmed by charger. Indicat= es > > > +the power limit from a charging source. > > > > > > CHARGE_CONTROL_LIMIT - current charge control limit setting > > > CHARGE_CONTROL_LIMIT_MAX - maximum charge control limit setting > > > diff --git a/drivers/power/supply/power_supply_sysfs.c b/drivers/powe= r/supply/power_supply_sysfs.c > > > index 5358a80d854f..860db617d241 100644 > > > --- a/drivers/power/supply/power_supply_sysfs.c > > > +++ b/drivers/power/supply/power_supply_sysfs.c > > > @@ -275,6 +275,8 @@ static struct device_attribute power_supply_attrs= [] =3D { > > > POWER_SUPPLY_ATTR(charge_control_limit), > > > POWER_SUPPLY_ATTR(charge_control_limit_max), > > > POWER_SUPPLY_ATTR(input_current_limit), > > > + POWER_SUPPLY_ATTR(input_voltage_limit), > > > + POWER_SUPPLY_ATTR(input_power_limit), > > > POWER_SUPPLY_ATTR(energy_full_design), > > > POWER_SUPPLY_ATTR(energy_empty_design), > > > POWER_SUPPLY_ATTR(energy_full), > > > diff --git a/include/linux/power_supply.h b/include/linux/power_suppl= y.h > > > index 2f9c201a54d1..ba135a5d8996 100644 > > > --- a/include/linux/power_supply.h > > > +++ b/include/linux/power_supply.h > > > @@ -122,6 +122,8 @@ enum power_supply_property { > > > POWER_SUPPLY_PROP_CHARGE_CONTROL_LIMIT, > > > POWER_SUPPLY_PROP_CHARGE_CONTROL_LIMIT_MAX, > > > POWER_SUPPLY_PROP_INPUT_CURRENT_LIMIT, > > > + POWER_SUPPLY_PROP_INPUT_VOLTAGE_LIMIT, > > > + POWER_SUPPLY_PROP_INPUT_POWER_LIMIT, > > > POWER_SUPPLY_PROP_ENERGY_FULL_DESIGN, > > > POWER_SUPPLY_PROP_ENERGY_EMPTY_DESIGN, > > > POWER_SUPPLY_PROP_ENERGY_FULL, > > > -- > > > 2.20.1 > > > > > > > -- > > Benson Leung > > Staff Software Engineer > > Chrome OS Kernel > > Google Inc. > > bleung@google.com > > Chromium OS Project > > bleung@chromium.org --e4ghregrusiggzmz Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCgAdFiEE72YNB0Y/i3JqeVQT2O7X88g7+poFAl0VDQAACgkQ2O7X88g7 +pqkhhAAlWCKoKEY+olvQ7v5gHO3kZB0Z5j8HEgtWE7KbkzVR0RmMq+dm0w7jOcu VNn9iYY/buXIRP/ey66XuQ8nYS/b9FGFsoxDsm7UVG9ps/7LTpgvhpIiN3hR5Aue BvwkIbBrE4lJSEtwuKKskOMP4+tUh6SLxVIuWkYBi3j9iW8+TquKLzIk/VLDqLlF jK+RlynXef5Ge+RNa8yAt0kz0GaRyDGIZf67FPQIvJ7qL/bjlsyJ21Bstq9wZqdf Ny06XGiY4nerdJelxnPIbLZrcZx9M4mb+LJSmJJ1ZNE2ofTduPv3FT5zMI4vq8+K /8aoKnp3DbpoQ/ubreqWAYpG1e/5Hs7kn1B3rDOXilOB4f96470f+ydDPzQ9aKuh SYxWkVEFoi2RcfsaLkYSC2JLTrHJG3n0IGEAxfdiV2Zd5orSlVfoz59EJR75EUAc nazikzvj62E2VHsUt3VvNpi1Gz2ojNhMqr2j4DJckvALujtORB38D65WfRlXbvej tJ0GLs3ItHnwe961+GWQOC/V/Wyon821hvigrlRhJHh17VZCWEFL3WnAuw51NejF F8VrrYbqkVNWCBTBEcjQ8L5RGz/uofBxg8g6mtHv7l+fSagk7KhVFO3N3Bm5FfJn 5rjIYw3/kID8EK7U82sMnG+QsR4TRJ8hqOeTtUXbZZV95rNmKHo= =Cf/l -----END PGP SIGNATURE----- --e4ghregrusiggzmz--