From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id DDD90C072B5 for ; Fri, 24 May 2019 10:20:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B572C20856 for ; Fri, 24 May 2019 10:20:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390420AbfEXKUG (ORCPT ); Fri, 24 May 2019 06:20:06 -0400 Received: from mga18.intel.com ([134.134.136.126]:27154 "EHLO mga18.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389448AbfEXKUG (ORCPT ); Fri, 24 May 2019 06:20:06 -0400 X-Amp-Result: UNSCANNABLE X-Amp-File-Uploaded: False Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by orsmga106.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 24 May 2019 03:20:05 -0700 X-ExtLoop1: 1 Received: from lahna.fi.intel.com (HELO lahna) ([10.237.72.157]) by fmsmga001.fm.intel.com with SMTP; 24 May 2019 03:20:02 -0700 Received: by lahna (sSMTP sendmail emulation); Fri, 24 May 2019 13:20:02 +0300 Date: Fri, 24 May 2019 13:20:02 +0300 From: Mika Westerberg To: Stefan Roese Cc: linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org, Andy Shevchenko , Yegor Yefremov , Greg Kroah-Hartman , Giulio Benetti Subject: Re: [PATCH 1/2 v2] serial: mctrl_gpio: Check if GPIO property exisits before requesting it Message-ID: <20190524102002.GT2781@lahna.fi.intel.com> References: <20190524094825.16151-1-sr@denx.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190524094825.16151-1-sr@denx.de> Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo User-Agent: Mutt/1.11.4 (2019-03-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, May 24, 2019 at 11:48:24AM +0200, Stefan Roese wrote: > This patch adds a check for the GPIOs property existence, before the > GPIO is requested. This fixes an issue seen when the 8250 mctrl_gpio > support is added (2nd patch in this patch series) on x86 platforms using > ACPI. > > Here Mika's comments from 2016-08-09: > > " > I noticed that with v4.8-rc1 serial console of some of our Broxton > systems does not work properly anymore. I'm able to see output but input > does not work. > > I bisected it down to commit 4ef03d328769eddbfeca1f1c958fdb181a69c341 > ("tty/serial/8250: use mctrl_gpio helpers"). > > The reason why it fails is that in ACPI we do not have names for GPIOs > (except when _DSD is used) so we use the "idx" to index into _CRS GPIO > resources. Now mctrl_gpio_init_noauto() goes through a list of GPIOs > calling devm_gpiod_get_index_optional() passing "idx" of 0 for each. The > UART device in Broxton has following (simplified) ACPI description: > > Device (URT4) > { > ... > Name (_CRS, ResourceTemplate () { > GpioIo (Exclusive, PullDefault, 0x0000, 0x0000, IoRestrictionOutputOnly, > "\\_SB.GPO0", 0x00, ResourceConsumer) > { > 0x003A > } > GpioIo (Exclusive, PullDefault, 0x0000, 0x0000, IoRestrictionOutputOnly, > "\\_SB.GPO0", 0x00, ResourceConsumer) > { > 0x003D > } > }) > > In this case it finds the first GPIO (0x003A which happens to be RX pin > for that UART), turns it into GPIO which then breaks input for the UART > device. This also breaks systems with bluetooth connected to UART (those > typically have some GPIOs in their _CRS). > > Any ideas how to fix this? > > We cannot just drop the _CRS index lookup fallback because that would > break many existing machines out there so maybe we can limit this to > only DT enabled machines. Or alternatively probe if the property first > exists before trying to acquire the GPIOs (using > device_property_present()). > " > > This patch implements the fix suggested by Mika in his statement above. > > Signed-off-by: Stefan Roese > Cc: Mika Westerberg Reviewed-by: Mika Westerberg