From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753277AbbJ0KJO (ORCPT ); Tue, 27 Oct 2015 06:09:14 -0400 Received: from mail-ob0-f172.google.com ([209.85.214.172]:36170 "EHLO mail-ob0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751902AbbJ0KJM (ORCPT ); Tue, 27 Oct 2015 06:09:12 -0400 MIME-Version: 1.0 In-Reply-To: <1445329509-6252-1-git-send-email-yamada.masahiro@socionext.com> References: <1445329509-6252-1-git-send-email-yamada.masahiro@socionext.com> Date: Tue, 27 Oct 2015 11:09:11 +0100 Message-ID: Subject: Re: [PATCH] pinctrl: uniphier: set input-enable before pin-muxing From: Linus Walleij To: Masahiro Yamada Cc: "linux-gpio@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@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 On Tue, Oct 20, 2015 at 10:25 AM, Masahiro Yamada wrote: > While IECTRL is disabled, input signals are pulled-down internally. > If pin-muxing is set up first, glitch signals (Low to High transition) > might be input to hardware blocks. > > Bad case scenario: > [1] The hardware block is already running before pinctrl is handled. > (the reset is de-asserted by default or by a firmware, for example) > [2] The pin-muxing is set up. The input signals to hardware block > are pulled-down by the chip-internal biasing. > [3] The pins are input-enabled. The signals from the board reach the > hardware block. > > Actually, one invalid character is input to the UART blocks for such > SoCs as PH1-LD4, PH1-sLD8, where UART devices start to run at the > power on reset. > > To avoid such problems, pins should be input-enabled before muxing. > > Fixes: 6e9088920258 ("pinctrl: UniPhier: add UniPhier pinctrl core support") > Signed-off-by: Masahiro Yamada > Reported-by: Dai Okamura > --- > > Hi Linus, > > If it is not too late, please apply this fix for Linux 4.3. It's too late at this point. Patch is applied for devel and will come into v4.4 and from there to -stable. Yours, Linus Walleij