From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx2.suse.de (cantor2.suse.de [195.135.220.15]) (using TLSv1 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 88B411A0067 for ; Thu, 2 Oct 2014 09:21:20 +1000 (EST) Message-ID: <542C8C69.2010509@suse.de> Date: Thu, 02 Oct 2014 01:21:13 +0200 From: Alexander Graf MIME-Version: 1.0 To: Scott Wood Subject: Re: [PATCH 00/20] powerpc: Convert power off logic to pm_power_off References: <1412170086-57971-1-git-send-email-agraf@suse.de> <1412203153.13320.352.camel@snotra.buserror.net> In-Reply-To: <1412203153.13320.352.camel@snotra.buserror.net> Content-Type: text/plain; charset=utf-8 Cc: Arnd Bergmann , Geoff Levand , Alistair Popple , Anatolij Gustschin , linuxppc-dev@lists.ozlabs.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On 02.10.14 00:39, Scott Wood wrote: > On Wed, 2014-10-01 at 15:27 +0200, Alexander Graf wrote: >> The generic Linux framework to power off the machine is a function pointer >> called pm_power_off. The trick about this pointer is that device drivers can >> potentially implement it rather than board files. >> >> Today on PowerPC we set pm_power_off to invoke our generic full machine power >> off logic which then calls ppc_md.power_off to invoke machine specific power >> off. >> >> However, when we want to add a power off GPIO via the "gpio-poweroff" driver, >> this card house falls apart. That driver only registers itself if pm_power_off >> is NULL to ensure it doesn't override board specific logic. However, since we >> always set pm_power_off to the generic power off logic (which will just not >> power off the machine if no ppc_md.power_off call is implemented), we can't >> implement power off via the generic GPIO power off driver. >> >> To fix this up, let's get rid of the ppc_md.power_off logic and just always use >> pm_power_off as was intended. Then individual drivers such as the GPIO power off >> driver can implement power off logic via that function pointer. >> >> With this patch set applied and a few patches on top of QEMU that implement a >> power off GPIO on the virt e500 machine, I can successfully turn off my virtual >> machine after halt. > > Are there any plans to handle restart similarly? I don't see an immediate need for it, as we do have access to reset via the guts device. I also don't see any generic driver in Linux that would implement reset via a gpio controller device, so apparently it's not incredibly common to implement reset via gpio. Alex