From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754187AbcGHIyU (ORCPT ); Fri, 8 Jul 2016 04:54:20 -0400 Received: from mezzanine.sirena.org.uk ([106.187.55.193]:56652 "EHLO mezzanine.sirena.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754055AbcGHIyO (ORCPT ); Fri, 8 Jul 2016 04:54:14 -0400 Date: Fri, 8 Jul 2016 10:53:38 +0200 From: Mark Brown To: Aleksandr Frid Cc: Doug Anderson , Laxman Dewangan , Boris Brezillon , Lee Jones , Brian Norris , "open list:ARM/Rockchip SoC..." , Heiko Stuebner , Thierry Reding , Liam Girdwood , "linux-kernel@vger.kernel.org" Message-ID: <20160708085338.GT6247@sirena.org.uk> References: <1467830521-15300-1-git-send-email-dianders@chromium.org> <577E1487.9010000@nvidia.com> <47095a54f7b44f8a98bdfe05cdea7865@HQMAIL106.nvidia.com> <364098370f214216ad14eda6487687e9@HQMAIL106.nvidia.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="dZoxY5VDSg+7Vbn9" Content-Disposition: inline In-Reply-To: <364098370f214216ad14eda6487687e9@HQMAIL106.nvidia.com> X-Cookie: You are always busy. User-Agent: Mutt/1.6.0 (2016-04-01) X-SA-Exim-Connect-IP: 137.158.22.235 X-SA-Exim-Mail-From: broonie@sirena.org.uk Subject: Re: [PATCH v2] regulator: pwm: Fix regulator ramp delay for continuous mode 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 --dZoxY5VDSg+7Vbn9 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, Jul 07, 2016 at 06:43:33PM +0000, Aleksandr Frid wrote: I'm not entirely sure what's wrong with your mail client here but your mails are essentially illegible. There appears to be some combination of top posting, reflowing quoted content to remove line breaks and extra levels of quoting. > >> > In the case that you don't need multiple steps then don't specify a regul= ator-ramp-delay, just a pwm-regulator-settle-us. > >> > Agreed >=20 > -----Original Message----- > From: dianders@google.com [mailto:dianders@google.com] On Behalf Of Doug = Anderson > Sent: Thursday, July 07, 2016 11:32 AM > To: Aleksandr Frid > Cc: Laxman Dewangan; Mark Brown; Boris Brezillon; Lee Jones; Brian Norris= ; open list:ARM/Rockchip SoC...; Heiko Stuebner; Thierry Reding; Liam Girdw= ood; linux-kernel@vger.kernel.org > Subject: Re: [PATCH v2] regulator: pwm: Fix regulator ramp delay for cont= inuous mode >=20 > Hi, >=20 > On Thu, Jul 7, 2016 at 11:23 AM, Aleksandr Frid wrote: > > Hi, > > > >>> > > In that case we should probably add a new PWM regulator property and no= t abuse the existing one. Maybe you use "pwm-regulator-settle-us" > > or something? > >>> > > Looks reasonable to me. > > > >>> > > actually the right thing is probably to implement=20 > > 'regulator-ramp-delay' as doing several small steps in that case > >>> > > Ramp delay uV/us is not a "real" metric for some PWM regulators with e= xponential transition -- as opposite to fixed slew-rate linear transition o= n other regulators. So splitting transition into multiple steps to implemen= t artificial (in this case) metric seems questionable. >=20 > In the case that you don't need multiple steps then don't specify a regul= ator-ramp-delay, just a pwm-regulator-settle-us. >=20 > ...the suggestion for multiple steps is because (so I'm told) it helps av= oid overshoot or undershoot problems. In general the whole point of rampin= g a regulator slowly is to avoid overshoot or undershoot problems. The "re= gulator-ramp-delay" property in Linux is a little odd because it sort of "d= escribes" the ramp delay and sort of "sets" > the ramp delay. Many PMICs allow you to set how fast the regulator will = ramp and this property is used to specify how the register in the PMIC shou= ld be set. However, it is also used as the actual delay in Linux. >=20 >=20 > -Doug --dZoxY5VDSg+7Vbn9 Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQEbBAEBCAAGBQJXf2oQAAoJECTWi3JdVIfQ3x0H+PJTskkBS1BS8NrZc8LwOe0i 4ezsSuEn3quyXp6htWj+jQCNygyBmAOqj8JVdPc2njER+VS+5gA1es/ZGpDOUbia SjVd8WS6OppC+PTFmZSaRkoKPp7FXLxJ03ltXtDqoyuLh1uPJsThDBqPcTGdvySA t4pg3jcOSjBlVOVkhAaOaGEnbQu5z1zgZPIt2tEE3c6ydDO2kHUXEDBqRXTXtL9f HAGD9RTBFldbJVldjWVZ5lnEzLZUVGqXLDT93a8c0Dp3Ccz42EGy1YsGlsdLw6N9 dQOakNETXG+zapsxA51SrtWa2EP+Df28jFATc1dJQ0J5nOVHDQPAAHkTFMi/gA== =bzBR -----END PGP SIGNATURE----- --dZoxY5VDSg+7Vbn9--