Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752941AbbLJJUN (ORCPT ); Thu, 10 Dec 2015 04:20:13 -0500 Received: from mail-wm0-f48.google.com ([74.125.82.48]:35380 "EHLO mail-wm0-f48.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751048AbbLJJUI (ORCPT ); Thu, 10 Dec 2015 04:20:08 -0500 MIME-Version: 1.0 In-Reply-To: <27901180.P9mpafrzx5@wuerfel> References: <1449610162-30543-1-git-send-email-john.stultz@linaro.org> <20151208220722.GG4000@usrtlx11787.corpusers.net> <27901180.P9mpafrzx5@wuerfel> Date: Thu, 10 Dec 2015 11:20:06 +0200 Message-ID: Subject: Re: [RFC][PATCH] misc: Introduce reboot_reason driver From: Tomas Winkler To: Arnd Bergmann Cc: John Stultz , Bjorn Andersson , lkml , Rob Herring , Pawel Moll , Mark Rutland , Ian Campbell , Kumar Gala , Vinay Simha BN , Haojian Zhuang , "devicetree@vger.kernel.org" , Android Kernel Team , Andy Gross , "linux-arm-msm@vger.kernel.org" Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2502 Lines: 56 On Thu, Dec 10, 2015 at 11:05 AM, Arnd Bergmann wrote: > On Wednesday 09 December 2015 17:32:02 John Stultz wrote: >> On Tue, Dec 8, 2015 at 2:07 PM, Bjorn Andersson >> wrote: >> > On Tue 08 Dec 13:29 PST 2015, John Stultz wrote: >> >> diff --git a/arch/arm/boot/dts/qcom-apq8064-nexus7-flo.dts b/arch/arm/boot/dts/qcom-apq8064-nexus7-flo.dts >> >> index 5183d18..ee5dcb7 100644 >> >> --- a/arch/arm/boot/dts/qcom-apq8064-nexus7-flo.dts >> >> +++ b/arch/arm/boot/dts/qcom-apq8064-nexus7-flo.dts >> >> @@ -282,6 +282,15 @@ >> >> }; >> >> }; >> >> >> >> + reboot_reason: reboot_reason@2a03f65c { >> >> + compatible = "reboot_reason"; >> >> + reg = <0x2A03F65C 0x4>; >> >> + reason,none = <0x77665501>; >> >> + reason,bootloader = <0x77665500>; >> >> + reason,recovery = <0x77665502>; >> >> + reason,oem = <0x6f656d00>; >> >> + }; >> >> + >> > >> > This address refers to IMEM, which is shared with a number of other >> > uses. So I think we should have a simple-mfd (and syscon) with this >> > within. >> >> So talking with Arnd some more it looked like IMEM was really just >> SRAM. Is that not the case, or is there something else special about >> it? Does it really need simple-mfd and syscon? I'm still fuzzy on how >> to use those for this. > > If it's SRAM, we should use the SRAM binding and not make it a syscon > device. What we can have however, is a mostly somewhat reboot-reason > driver that is able to access an SRAM device or something else, > depending on what the platform and/or bootloader has. > > HTC's Nexus 9 apparently uses a section of normal RAM for communication > between bootloader and kernel, so we'd also need a way to hook into > a driver for that. > > Arnd Intel uses EFI variables for that on some AOS platforms. There is a need for persistent storage abstraction and generalize the reboot reasons strings. Second, I wonder why this is submitted under drivers/misc when it doesn't bind the misc API. Thanks Tomas -- 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/