From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752759Ab3K3QT7 (ORCPT ); Sat, 30 Nov 2013 11:19:59 -0500 Received: from mail.kmu-office.ch ([178.209.48.102]:35549 "EHLO mail.kmu-office.ch" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752608Ab3K3QTp (ORCPT ); Sat, 30 Nov 2013 11:19:45 -0500 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Date: Sat, 30 Nov 2013 17:24:14 +0100 From: Stefan Agner To: Lucas Stach Cc: Stephen Warren , thierry.reding@gmail.com, sameo@linux.intel.com, dev@lynxeye.de, mark.rutland@arm.com, linux-tegra@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH 3/3] ARM: tegra: set SM2 voltage correct In-Reply-To: <1385632196.5838.4.camel@weser.hi.pengutronix.de> References: <5296281C.1060403@wwwdotorg.org> <1385632196.5838.4.camel@weser.hi.pengutronix.de> Message-ID: User-Agent: Roundcube Webmail/0.9.5 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Am 2013-11-28 10:49, schrieb Lucas Stach: > Am Mittwoch, den 27.11.2013, 10:13 -0700 schrieb Stephen Warren: >> On 11/26/2013 04:45 PM, Stefan Agner wrote: >> > Set the requested SM2 voltage to the correct value of 1.8V. The value >> > before used to work on TPS658623 since the driver applied a wrong >> > voltage table too. However, the TPS658643 used on newer devices uses >> > yet another voltage table and those broke that compatibility. The >> > regulator driver now has the correct voltage table for both regulator >> > versions and those the correct voltage can be used in this device >> > tree. >> >> One thing you haven't called out explicitly here is that this series is >> an incompatible change to the DT, since the old buggy driver used to >> allow old buggy DT content to accidentally work. >> > The current (wrong and potentially dangerous) DT content only worked on > the engineering sample models. So this change definitely does improve > the situation, even with the risk of breaking a small fraction of > working boards. On the released modules, the current value ends in a freeze during boot-up (since the wrong voltage table results in a too low voltage). When I use 1.8V in the device tree, the old drivers refuses to set any voltage. The regulators default/bootloader settings work then better than the wrongfully applied values (tested on a new device). The probe just fails: [ 0.243864] tps6586x-regulator tps6586x-regulator: failed to register regulator REG-SM_2 [ 0.244317] tps6586x-regulator: probe of tps6586x-regulator failed with error -22 So, for newer modules, the incompatible 1.8V DT results in a successful boot. Since we don't have a regulator driver at all, likely other things are broken at that situation... -- Stefan