From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755327AbbI2PAe (ORCPT ); Tue, 29 Sep 2015 11:00:34 -0400 Received: from mezzanine.sirena.org.uk ([106.187.55.193]:53885 "EHLO mezzanine.sirena.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753905AbbI2PAZ (ORCPT ); Tue, 29 Sep 2015 11:00:25 -0400 Date: Tue, 29 Sep 2015 16:00:17 +0100 From: Mark Brown To: Sascha Hauer Cc: linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, Liam Girdwood , kernel@pengutronix.de, "Rafael J. Wysocki" , Viresh Kumar Message-ID: <20150929150017.GR30445@sirena.org.uk> References: <20150925090724.GH7858@pengutronix.de> <20150925164726.GI30445@sirena.org.uk> <20150929080044.GS7858@pengutronix.de> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="25AjPoXvrcQXrjmi" Content-Disposition: inline In-Reply-To: <20150929080044.GS7858@pengutronix.de> X-Cookie: NOBODY EXPECTS THE SPANISH INQUISITION! User-Agent: Mutt/1.5.23 (2014-03-12) X-SA-Exim-Connect-IP: 94.175.94.161 X-SA-Exim-Mail-From: broonie@sirena.org.uk Subject: Re: Voltage setting on chained regulators, how? X-SA-Exim-Version: 4.2.1 (built Mon, 26 Dec 2011 16:24:06 +0000) X-SA-Exim-Scanned: Yes (on mezzanine.sirena.org.uk) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --25AjPoXvrcQXrjmi Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Tue, Sep 29, 2015 at 10:00:44AM +0200, Sascha Hauer wrote: > On Fri, Sep 25, 2015 at 09:47:26AM -0700, Mark Brown wrote: > > I suspect you always want the LDO in there to clean the supply up, it's > > just a more serious issue when more power is being drawn. > I just had a look at the i.MX6 datasheets and saw that while it's > possible to put the LDOs in bypass mode the expected lifetime of the SoC > decreases without the LDOs. So it seems better to let them enabled and > just make the voltage drop as small as possible. Yeah, that sounds pretty standard. It would be really good to get support for minimising the voltage drop over the LDO, there are going to be quite a few systems which could get a power consumption benefit from dynamically tuning the voltages of DCDCs like this. --25AjPoXvrcQXrjmi Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQEcBAEBCAAGBQJWCqeBAAoJECTWi3JdVIfQrA0H/RV2X4xFg20mPtDq+VBXGM1w p4fLr42w6n2X66LVl+7f91X/Mi+B3Nf4M5F/vAMhFHSKBiahhCT66lT7L5QjTUkd 6AVUMl2GBkuzPEmGve9rtP2nOzWeB6GnfCDnW5VDyZKQ4e085zS059o3H3o3DRMQ XSyrZiBjItdlR9JdUsin0JUzzMtho9dlM7MpKQQDAh8Yo9uiTaKEAfhJ/HwQVqjA I0jhW0ZPfP52xI21YP03e/6BZISQvNVPU4Ucd5Mpfq9b8cG51gVi+uCufh5IktkD WAOU4NDx9mXXOt09JawTK2lhoBjMiI4cePw2dE52uJsRUf/II+FTmn2jtbW/tF4= =aD7d -----END PGP SIGNATURE----- --25AjPoXvrcQXrjmi--