Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753534Ab2KUB4q (ORCPT ); Tue, 20 Nov 2012 20:56:46 -0500 Received: from hqemgate03.nvidia.com ([216.228.121.140]:17870 "EHLO hqemgate03.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752522Ab2KUB4o (ORCPT ); Tue, 20 Nov 2012 20:56:44 -0500 X-PGP-Universal: processed; by hqnvupgp07.nvidia.com on Tue, 20 Nov 2012 17:56:38 -0800 From: Alex Courbot To: Tomi Valkeinen CC: Anton Vorontsov , Stephen Warren , Thierry Reding , Mark Zhang , Grant Likely , Rob Herring , Mark Brown , David Woodhouse , Arnd Bergmann , "linux-tegra@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , "linux-fbdev@vger.kernel.org" , "devicetree-discuss@lists.ozlabs.org" , "linux-pm@vger.kernel.org" , Alexandre Courbot Subject: Re: [PATCHv9 1/3] Runtime Interpreted Power Sequences Date: Wed, 21 Nov 2012 10:56:36 +0900 Message-ID: <4316169.5QXVzv7peZ@percival> Organization: NVIDIA User-Agent: KMail/4.9.3 (Linux/3.6.6-1-ARCH; KDE/4.9.3; x86_64; ; ) In-Reply-To: <50AB9832.90709@ti.com> References: <1353149747-31871-1-git-send-email-acourbot@nvidia.com> <1353149747-31871-2-git-send-email-acourbot@nvidia.com> <50AB9832.90709@ti.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2064 Lines: 41 Hi Tomi, On Tuesday 20 November 2012 22:48:18 Tomi Valkeinen wrote: > I guess there's a reason, but the above looks a bit inconsistent. For > gpio you define the gpio resource inside the step. For power and pwm the > resource is defined before the steps. Why wouldn't "pwm = <&pwm 2 > 5000000>;" work in step2? That's mostly a framework issue. Most frameworks do not export a function that allow to dereference a phandle - they expect resources to be declared right under the device node and accessed by name through foo_get(device, name). So using phandles in power sequences would require to export these additional functions and also opens the door to some inconsistencies - for instance, your PWM phandle could be referenced a second time in the sequence with a different period - how do you know that these are actually referring the same PWM device? > > +When a power sequence is run, its steps is executed one after the other > > until +one step fails or the end of the sequence is reached. > > The document doesn't give any hint of what the driver should do if > running the power sequence fails. Run the "opposite" power sequence? > Will that work for all resources? I'm mainly thinking of a case where > each enable of the resource should be matched by a disable, i.e. you > can't call disable if no enable was called. We discussed that issue already (around v5 I think) and the conclusion was that it should be up to the driver. When we simply enable/disable resources it is easy to revert, but in the future non-boolean properties will likely be introduced, and these cannot easily be reverted. Moreover some drivers might have more complex recovery needs. This deserves more discussion I think, as I'd like to have some "generic" recovery mechanism that covers most of the cases. Alex. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/