From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753608AbcD0QaY (ORCPT ); Wed, 27 Apr 2016 12:30:24 -0400 Received: from mezzanine.sirena.org.uk ([106.187.55.193]:50168 "EHLO mezzanine.sirena.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753196AbcD0QaT (ORCPT ); Wed, 27 Apr 2016 12:30:19 -0400 Date: Wed, 27 Apr 2016 17:30:08 +0100 From: Mark Brown To: Hans de Goede Cc: Liam Girdwood , Maxime Ripard , Chen-Yu Tsai , Linux Kernel Mailing List Message-ID: <20160427163008.GB3217@sirena.org.uk> References: <1461765568-15828-1-git-send-email-hdegoede@redhat.com> <1461765568-15828-4-git-send-email-hdegoede@redhat.com> <20160427151219.GV3217@sirena.org.uk> <20160427154819.GY3217@sirena.org.uk> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="DVODceqoHWbxWDF1" Content-Disposition: inline In-Reply-To: X-Cookie: Tomorrow, you can be anywhere. User-Agent: Mutt/1.5.24 (2015-08-30) X-SA-Exim-Connect-IP: 2a01:348:6:8808:fab::3 X-SA-Exim-Mail-From: broonie@sirena.org.uk Subject: Re: [PATCH v2 3/3] regulator: axp20x: Fix axp22x ldo_io registration error on cold boot 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 --DVODceqoHWbxWDF1 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, Apr 27, 2016 at 06:04:53PM +0200, Hans de Goede wrote: > On 27-04-16 17:48, Mark Brown wrote: > >Well, I guess someone can just measure what happens? > What happens will likely depend on the pmic input voltage, > which can be either 5V from a charger / usb or can be approx > 3.8V from a lion or lipo battery. All linear regulators in > the axp20x / axp22x pmic are listed as having a max output > voltage of 3.3V, this likely has to do with the minimum > voltage drop compared to the input value. That sounds like it's a non-regulating bypass mode which is something we support; if the regulator is in bypass mode we'll look for the voltage =66rom the parent rather than in the child regulator. > So in some conditions the output voltage at a 0x1f register > value may very well be different then at others. IMHO we > should just avoid any out of spec. values. As I've said before it'll be read only unless the system integrator explicitly says otherwise. > I believe that we really need to write an in-spec value to the > register controlling the voltage, before enabling this regulator > (which is done by selecting the mux to connect it to the pin). We have a strong policy that we don't touch the hardware unless we are explicitly told it's OK to do so by the system integration, it's very hard to tell if things are in general going to be safe and if we get things wrong that could lead to physical damage. --DVODceqoHWbxWDF1 Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQEcBAEBCAAGBQJXIOkOAAoJECTWi3JdVIfQpDMH/AhRQnO+MSpPdVth/NIfLwf8 pKdGNOcEi8iHASA/jJ0iOq8uO5DCYa87eqnm/ZveHvI8T14pVDYKkikKzTAvsvKk ARxmmUOw07qDhF9ujScIYDwYdczuxarrr5sq4Y08Sfmkk2+iZC9PviqDNkIIV5rE ALRU9JvaYYcJcrsLd5TCjuS+f/CjzX6LOiag3stPf6OYuZlsK8ulp+VMlSVHoaY2 cKlq2qQ6SkcMVnc3DZ7Mou8MCZJsfjwfWU8yOiX8n5IswzaZFp2AGhjhm53jIjQe IhKYFIf56XfGl2mIDNPLUKz4lQvMzddCh2xx/xJLRdgU3VCSrLeXMMH8hvk0GJw= =K1Qd -----END PGP SIGNATURE----- --DVODceqoHWbxWDF1--