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=-0.8 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 67945C072B5 for ; Fri, 24 May 2019 12:17:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2EB7A2081C for ; Fri, 24 May 2019 12:17:38 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="key not found in DNS" (0-bit key) header.d=micronovasrl.com header.i=@micronovasrl.com header.b="jxTV+ZGu" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391498AbfEXMRh (ORCPT ); Fri, 24 May 2019 08:17:37 -0400 Received: from mail.micronovasrl.com ([212.103.203.10]:49762 "EHLO mail.micronovasrl.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2391465AbfEXMRh (ORCPT ); Fri, 24 May 2019 08:17:37 -0400 X-Greylist: delayed 498 seconds by postgrey-1.27 at vger.kernel.org; Fri, 24 May 2019 08:17:35 EDT Received: from mail.micronovasrl.com (mail.micronovasrl.com [127.0.0.1]) by mail.micronovasrl.com (Postfix) with ESMTP id 40252B014C0 for ; Fri, 24 May 2019 14:09:16 +0200 (CEST) Authentication-Results: mail.micronovasrl.com (amavisd-new); dkim=pass reason="pass (just generated, assumed good)" header.d=micronovasrl.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=micronovasrl.com; h=content-transfer-encoding:content-language:content-type :content-type:in-reply-to:mime-version:user-agent:date:date :message-id:from:from:references:to:subject:subject; s=dkim; t= 1558699755; x=1559563756; bh=8zfBt/DHoA9altCnYmg1awpFAXKb2Mxggpk GeiE/K20=; b=jxTV+ZGurVcKwV0GxpY+YOkA+euNmp+XEVSHnXIWYPv53JEPzsi 2b3C5WDOvlUm8s84GTK4Z5IcucxdSpKNLzynSX08Ufbonpye3zlUFdYRxIqMMg9Y hnxYAeGt3X+CnhneRyu1Qb47Ds+PyxaIShfJvcQNl/mQUcvLfphgS45g= X-Virus-Scanned: Debian amavisd-new at mail.micronovasrl.com Received: from mail.micronovasrl.com ([127.0.0.1]) by mail.micronovasrl.com (mail.micronovasrl.com [127.0.0.1]) (amavisd-new, port 10026) with ESMTP id P7ak0tdWEcQq for ; Fri, 24 May 2019 14:09:15 +0200 (CEST) Received: from [192.168.2.18] (88-149-228-83.v4.ngi.it [88.149.228.83]) by mail.micronovasrl.com (Postfix) with ESMTPSA id D1A24B0008B; Fri, 24 May 2019 14:09:14 +0200 (CEST) Subject: Re: [PATCH 1/2 v2] serial: mctrl_gpio: Check if GPIO property exisits before requesting it To: Stefan Roese , Andy Shevchenko , Mika Westerberg Cc: "open list:SERIAL DRIVERS" , Linux Kernel Mailing List , Andy Shevchenko , Yegor Yefremov , Greg Kroah-Hartman References: <20190524094825.16151-1-sr@denx.de> <20190524102002.GT2781@lahna.fi.intel.com> <287cdcc8-9a8f-4583-8be9-bd1f95936733@denx.de> From: Giulio Benetti Message-ID: <2036b776-8b8e-d1fd-00b4-c3b046f25a2f@micronovasrl.com> Date: Fri, 24 May 2019 14:09:16 +0200 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.7.0 MIME-Version: 1.0 In-Reply-To: <287cdcc8-9a8f-4583-8be9-bd1f95936733@denx.de> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: it Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello Stefan, Il 24/05/2019 13:29, Stefan Roese ha scritto: > On 24.05.19 13:11, Andy Shevchenko wrote: >> On Fri, May 24, 2019 at 1:21 PM Mika Westerberg >> wrote: >>> >>> 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. >>>> >> >> We have a board where ASL provides _DSD for CTS and RxD pins. >> I'm afraid this won't work on it. > > With "won't work" you mean, that the GPIO can't be used for modem > control in this case in the current implementation (with this > patchset)? Or do you mean, that the breakage (input does not work > on Broxton systems) will not be solved by this patch? > > If its the former, then I think that solving this issue is something > for a new patch, to support modem-control on such platforms as well > (if needed). > > Please note that this patch is not trying to get modem-control working > on such ACPI based systems. Its targeted for device-tree enabled > platforms, using the 8250 serial driver, here specifically a MIPS > MT7688 based board. And just wants to fix the latter issue mentioned > above so that the 8250 modem-control support can be accepted in > mainline. Take a look here: https://lkml.org/lkml/2018/6/5/253 It's about waking up 8250 UART. As I remember that is the problem. I wanted to try to fix it but had no time. What it broken as I remember is the capability to wake up linux on uart RX. Hope I've understood right at that time. Best regards -- Giulio Benetti CTO MICRONOVA SRL Sede: Via A. Niedda 3 - 35010 Vigonza (PD) Tel. 049/8931563 - Fax 049/8931346 Cod.Fiscale - P.IVA 02663420285 Capitale Sociale € 26.000 i.v. Iscritta al Reg. Imprese di Padova N. 02663420285 Numero R.E.A. 258642 >> Basically we need to understand the use of the GPIOs in UART. In our >> case it's an out-of-band wake up source for UART. >> Simply requiring GPIOs to be present is not enough. >> >> Perhaps property like 'modem-control-gpio-in-use' (this seems a bad >> name, given for sake of example). > > Thanks, > Stefan >