From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753374AbcANKCs (ORCPT ); Thu, 14 Jan 2016 05:02:48 -0500 Received: from comal.ext.ti.com ([198.47.26.152]:44853 "EHLO comal.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752839AbcANKCo (ORCPT ); Thu, 14 Jan 2016 05:02:44 -0500 Subject: Re: [PATCH 1/3] ARM: dts: omap5-board-common: enable rtc and charging of backup battery To: Nishanth Menon , Tony Lindgren , Nishanth Menon References: <001346CD-CF31-4FEF-B406-B89EEBDFA063@goldelico.com> <56966558.1070608@ti.com> <569669C5.2070200@ti.com> <20160113164856.GF12777@atomide.com> <5696896F.4090309@ti.com> <20160113180006.GJ12777@atomide.com> <2B99611A-5D2E-4D17-A17D-0150516109FD@goldelico.com> <56969800.5010206@ti.com> <5696A002.6050402@ti.com> <20160113194032.GL12777@atomide.com> <5696D097.3040208@gmail.com> CC: "H. Nikolaus Schaller" , Grygorii Strashko , Laxman Dewangan , =?UTF-8?Q?Beno=c3=aet_Cousson?= , Rob Herring , Pawel Moll , Mark Rutland , Ian Campbell , Kumar Gala , Russell King , linux-omap , , LKML , Marek Belisko , =?UTF-8?Q?Gra=c5=bevydas_Ignotas?= , Keerthy From: Keerthy Message-ID: <56977211.8070206@ti.com> Date: Thu, 14 Jan 2016 15:31:53 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.2.0 MIME-Version: 1.0 In-Reply-To: <5696D097.3040208@gmail.com> Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thursday 14 January 2016 04:02 AM, Nishanth Menon wrote: > On 01/13/2016 01:40 PM, Tony Lindgren wrote: > >> Anyways, considering what's been discussed, after the minimal RTC fix >> we could also add code to allow the TWL driver optionally configure the >> GPIO. This way the TWL driver could also check the GPIO state in case >> some out-of-our-control mystery software goes tweak the msecure pin >> state. > > I dont even know how that will work: > If you are using MSECURE as it is intended to be, then you'd mux it to > msecure, which means that GPIO read is just a waste of time - you dont > even mux it to external world. Now, some SoCs like DRA7 has input lines > always connected. even assuming this is for such a case: > a) when you are running linux, you are already in nonsecure - it needs > no read of MSECURE GPIO to figure that out. > b) when you are in secure world, Linux wont be running either. > > Reading from GPIO is just misguided in my opinion. firewalls are not > reconfigured, and muxes are usually done a single time. > > Or the RTC driver could just check that the bits really change >> after= writing them. Then we would at least know things are not working >> right for the TWL related RTC drivers. > > that is reasonable to check, but just a overhead - anyways, just > isolated to palmas-rtc.. fail reason maynot always be issues with > MSECURE mux.. it could be very well be 32k clk fail etc.. but yeah - > that might give a hint that there is an issue.. > IIRC without configuring the mux mode of gpio234 to msecure mode we were unable to write to the rtc registers. Hence configured it one time at boot.