From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sascha Hauer Date: Thu, 13 Sep 2012 07:18:29 +0000 Subject: Re: [PATCH v6 1/4] Runtime Interpreted Power Sequences Message-Id: <20120913071829.GE6180@pengutronix.de> List-Id: 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> In-Reply-To: <1347519807.7471.45.camel@lappyti> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Tomi Valkeinen 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-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "linux-fbdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org" , "linux-pm-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "linux-doc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" 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: > > > > > > > > > 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 some > > > > > configuration to accomplish the task at hand. It could be rather > > > > > difficult to handle it with a generic power sequence. > > > > > > > > Right. Note that this framework is supposed to be extended - I would like to > > > > at least add regulator voltage setting, and maybe even support for clocks and > > > > pinmux (but that might be out of place). > > > > > > 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. These memory writes can be avoided when these registers are abstracted as a regular gpio/regulator/pwm driver. > > > And so > > > on. Where's the limit what it should contain? Can we soon write full > > > drivers with the DT data? =) > > > > I have this concern aswell, that's why I'm sceptical about this patch > > set. But what are the alternatives? Adding power code to the drivers and > > thus adding board specific code to them is backwards. > > As was pointed out in earlier posts in this thread, these are almost > always device specific, not board specific. > > Do you have examples of board specific power sequences or such? 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. Sascha -- Pengutronix e.K. | | Industrial Linux Solutions | http://www.pengutronix.de/ | Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sascha Hauer Subject: Re: [PATCH v6 1/4] Runtime Interpreted Power Sequences Date: Thu, 13 Sep 2012 09:18:29 +0200 Message-ID: <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> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <1347519807.7471.45.camel@lappyti> Sender: linux-tegra-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Tomi Valkeinen 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-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "linux-fbdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org" , "linux-pm-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "linux-doc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" List-Id: linux-tegra@vger.kernel.org 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: > > > > > > > > > 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 some > > > > > configuration to accomplish the task at hand. It could be rather > > > > > difficult to handle it with a generic power sequence. > > > > > > > > Right. Note that this framework is supposed to be extended - I would like to > > > > at least add regulator voltage setting, and maybe even support for clocks and > > > > pinmux (but that might be out of place). > > > > > > 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. These memory writes can be avoided when these registers are abstracted as a regular gpio/regulator/pwm driver. > > > And so > > > on. Where's the limit what it should contain? Can we soon write full > > > drivers with the DT data? =) > > > > I have this concern aswell, that's why I'm sceptical about this patch > > set. But what are the alternatives? Adding power code to the drivers and > > thus adding board specific code to them is backwards. > > As was pointed out in earlier posts in this thread, these are almost > always device specific, not board specific. > > Do you have examples of board specific power sequences or such? 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. Sascha -- Pengutronix e.K. | | Industrial Linux Solutions | http://www.pengutronix.de/ | Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756117Ab2IMHSs (ORCPT ); Thu, 13 Sep 2012 03:18:48 -0400 Received: from metis.ext.pengutronix.de ([92.198.50.35]:36001 "EHLO metis.ext.pengutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752681Ab2IMHSq (ORCPT ); Thu, 13 Sep 2012 03:18:46 -0400 Date: Thu, 13 Sep 2012 09:18:29 +0200 From: Sascha Hauer To: Tomi Valkeinen 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" Subject: Re: [PATCH v6 1/4] Runtime Interpreted Power Sequences Message-ID: <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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1347519807.7471.45.camel@lappyti> X-Sent-From: Pengutronix Hildesheim X-URL: http://www.pengutronix.de/ X-IRC: #ptxdist @freenode X-Accept-Language: de,en X-Accept-Content-Type: text/plain X-Uptime: 09:13:06 up 81 days, 22:24, 62 users, load average: 0.59, 0.77, 0.66 User-Agent: Mutt/1.5.21 (2010-09-15) X-SA-Exim-Connect-IP: 2001:6f8:1178:2:21e:67ff:fe11:9c5c X-SA-Exim-Mail-From: sha@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-kernel@vger.kernel.org Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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: > > > > > > > > > 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 some > > > > > configuration to accomplish the task at hand. It could be rather > > > > > difficult to handle it with a generic power sequence. > > > > > > > > Right. Note that this framework is supposed to be extended - I would like to > > > > at least add regulator voltage setting, and maybe even support for clocks and > > > > pinmux (but that might be out of place). > > > > > > 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. These memory writes can be avoided when these registers are abstracted as a regular gpio/regulator/pwm driver. > > > And so > > > on. Where's the limit what it should contain? Can we soon write full > > > drivers with the DT data? =) > > > > I have this concern aswell, that's why I'm sceptical about this patch > > set. But what are the alternatives? Adding power code to the drivers and > > thus adding board specific code to them is backwards. > > As was pointed out in earlier posts in this thread, these are almost > always device specific, not board specific. > > Do you have examples of board specific power sequences or such? 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. Sascha -- Pengutronix e.K. | | Industrial Linux Solutions | http://www.pengutronix.de/ | Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |