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=-0.7 required=3.0 tests=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 4252AC31E44 for ; Fri, 14 Jun 2019 09:29:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 214D72133D for ; Fri, 14 Jun 2019 09:29:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727021AbfFNJ3j (ORCPT ); Fri, 14 Jun 2019 05:29:39 -0400 Received: from mx2.mailbox.org ([80.241.60.215]:35582 "EHLO mx2.mailbox.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726479AbfFNJ3j (ORCPT ); Fri, 14 Jun 2019 05:29:39 -0400 Received: from smtp1.mailbox.org (smtp1.mailbox.org [80.241.60.240]) (using TLSv1.2 with cipher ECDHE-RSA-CHACHA20-POLY1305 (256/256 bits)) (No client certificate requested) by mx2.mailbox.org (Postfix) with ESMTPS id 8DF5FA1091; Fri, 14 Jun 2019 11:29:35 +0200 (CEST) X-Virus-Scanned: amavisd-new at heinlein-support.de Received: from smtp1.mailbox.org ([80.241.60.240]) by hefe.heinlein-support.de (hefe.heinlein-support.de [91.198.250.172]) (amavisd-new, port 10030) with ESMTP id yKkjF9F1R2O0; Fri, 14 Jun 2019 11:29:31 +0200 (CEST) Subject: Re: [PATCH 1/3 v6] serial: mctrl_gpio: Check if GPIO property exisits before requesting it To: Yegor Yefremov , Andy Shevchenko Cc: linux-serial@vger.kernel.org, kernel list , Mika Westerberg , Greg Kroah-Hartman , Giulio Benetti References: <20190613154542.32438-1-sr@denx.de> <20190613170802.GE9224@smile.fi.intel.com> From: Stefan Roese Message-ID: <0bf6629c-cedf-e1dd-b42b-989c6711d390@denx.de> Date: Fri, 14 Jun 2019 11:29:29 +0200 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 14.06.19 11:04, Yegor Yefremov wrote: > On Thu, Jun 13, 2019 at 7:08 PM Andy Shevchenko > wrote: >> >> On Thu, Jun 13, 2019 at 05:45:40PM +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. >>> >> >> Reviewed-by: Andy Shevchenko > > I cannot compile the driver without adding #include > to drivers/tty/serial/serial_mctrl_gpio.c. > > My platform is AM335X (OMAP3). I've tried the patches both against the > main repo and also tty-next. > > Other than that everything is working. Thanks for reporting. I'll wait a bit for other review comments and tests (thanks Andy) and will then send v7 with this header included (and compile tested on OMAP3) later next week. BTW: Could you please add a Tested-by-tag with the next version? Thanks, Stefan