From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756555Ab2IMH2Y (ORCPT ); Thu, 13 Sep 2012 03:28:24 -0400 Received: from na3sys009aog102.obsmtp.com ([74.125.149.69]:49238 "EHLO na3sys009aog102.obsmtp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756241Ab2IMH1S (ORCPT ); Thu, 13 Sep 2012 03:27:18 -0400 Message-ID: <1347521231.7471.51.camel@lappyti> Subject: Re: [PATCH v6 1/4] Runtime Interpreted Power Sequences From: Tomi Valkeinen To: Sascha Hauer Cc: Alex Courbot , Stephen Warren , Thierry Reding , Simon Glass , Grant Likely , Rob Herring , Mark Brown , Anton Vorontsov , David Woodhouse , Arnd Bergmann , Leela Krishna Amudala , "linux-tegra@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-fbdev@vger.kernel.org" , "devicetree-discuss@lists.ozlabs.org" , "linux-pm@vger.kernel.org" , "linux-doc@vger.kernel.org" Date: Thu, 13 Sep 2012 10:27:11 +0300 In-Reply-To: <20120913071829.GE6180@pengutronix.de> References: <1347443867-18868-1-git-send-email-acourbot@nvidia.com> <1464760.6eqxJ2IzZ2@percival> <1347517377.7471.23.camel@lappyti> <2689722.93BQTh4lSC@percival> <1347519249.7471.42.camel@lappyti> <20120913070012.GC6180@pengutronix.de> <1347519807.7471.45.camel@lappyti> <20120913071829.GE6180@pengutronix.de> Content-Type: multipart/signed; micalg="pgp-sha1"; protocol="application/pgp-signature"; boundary="=-k/2ptgd5nhGu/j+xHFPM" X-Mailer: Evolution 3.2.3-0ubuntu6 Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --=-k/2ptgd5nhGu/j+xHFPM Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Thu, 2012-09-13 at 09:18 +0200, Sascha Hauer wrote: > On Thu, Sep 13, 2012 at 10:03:27AM +0300, Tomi Valkeinen wrote: > > On Thu, 2012-09-13 at 09:00 +0200, Sascha Hauer wrote: > > > On Thu, Sep 13, 2012 at 09:54:09AM +0300, Tomi Valkeinen wrote: > > > > On Thu, 2012-09-13 at 15:36 +0900, Alex Courbot wrote: > > > > > On Thursday 13 September 2012 14:22:57 Tomi Valkeinen wrote: > > > > > =20 > > > > > > However, I fear these board specific things may be quite a bit = anything, > > > > > > so it may well be pwm, gpios and regulators are not enough for = them. For > > > > > > example, there could be an FPGA on the board which requires som= e > > > > > > configuration to accomplish the task at hand. It could be rathe= r > > > > > > difficult to handle it with a generic power sequence. > > > > >=20 > > > > > Right. Note that this framework is supposed to be extended - I wo= uld like to=20 > > > > > at least add regulator voltage setting, and maybe even support fo= r clocks and=20 > > > > > pinmux (but that might be out of place). > > > >=20 > > > > Yes, that's one concern of mine... I already can imagine someone > > > > suggesting adding conditionals to the power sequence data. Perhaps = also > > > > direct memory read/writes so you can twiddle registers directly. >=20 > These memory writes can be avoided when these registers are abstracted > as a regular gpio/regulator/pwm driver. Only if they are gpios/regulators/pwms. Yes, I agree most of the possible things to configure would be among those (or perhaps pinmuxing). But there's always the odd one that's not one of those. > > Do you have examples of board specific power sequences or such? >=20 > Sure, tons of. One board needs a gpio to be set high to enable backlight, > the next one to low, a regulator has to be enabled, and to avoid > flickering a certain timing has to be ensured. This is all highly board > specific. Okay. In my experience these have always been device specific. In the case of backlight, the backlight device requires one gpio to be set high, other one low, etc. Can you share a bit more what kind of HW configuration you have that requires this? The backlight is not a single piece of HW added to the board (or embedded into a panel module), but consists of multiple HW blocks integrated in a custom way to the board? 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