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=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,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 90C57C072B5 for ; Fri, 24 May 2019 09:48:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5EBD220815 for ; Fri, 24 May 2019 09:48:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390267AbfEXJsq (ORCPT ); Fri, 24 May 2019 05:48:46 -0400 Received: from mx2.mailbox.org ([80.241.60.215]:46260 "EHLO mx2.mailbox.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389911AbfEXJsq (ORCPT ); Fri, 24 May 2019 05:48:46 -0400 Received: from smtp1.mailbox.org (smtp1.mailbox.org [IPv6:2001:67c:2050:105:465:1:1:0]) (using TLSv1.2 with cipher ECDHE-RSA-CHACHA20-POLY1305 (256/256 bits)) (No client certificate requested) by mx2.mailbox.org (Postfix) with ESMTPS id 92B1DA1064; Fri, 24 May 2019 11:48:43 +0200 (CEST) X-Virus-Scanned: amavisd-new at heinlein-support.de Received: from smtp1.mailbox.org ([80.241.60.240]) by spamfilter06.heinlein-hosting.de (spamfilter06.heinlein-hosting.de [80.241.56.125]) (amavisd-new, port 10030) with ESMTP id aWeop9YRr6Wt; Fri, 24 May 2019 11:48:26 +0200 (CEST) From: Stefan Roese To: linux-serial@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Mika Westerberg , Andy Shevchenko , Yegor Yefremov , Greg Kroah-Hartman , Giulio Benetti Subject: [PATCH 1/2 v2] serial: mctrl_gpio: Check if GPIO property exisits before requesting it Date: Fri, 24 May 2019 11:48:24 +0200 Message-Id: <20190524094825.16151-1-sr@denx.de> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 Cc: Andy Shevchenko Cc: Yegor Yefremov Cc: Greg Kroah-Hartman Cc: Giulio Benetti --- v2: - Include the problem description and analysis from Mika into the commit text, as suggested by Greg. drivers/tty/serial/serial_mctrl_gpio.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/drivers/tty/serial/serial_mctrl_gpio.c b/drivers/tty/serial/serial_mctrl_gpio.c index 39ed56214cd3..cac50b20a119 100644 --- a/drivers/tty/serial/serial_mctrl_gpio.c +++ b/drivers/tty/serial/serial_mctrl_gpio.c @@ -116,6 +116,13 @@ struct mctrl_gpios *mctrl_gpio_init_noauto(struct device *dev, unsigned int idx) for (i = 0; i < UART_GPIO_MAX; i++) { enum gpiod_flags flags; + char *gpio_str; + + /* Check if GPIO property exists and continue if not */ + gpio_str = kasprintf(GFP_KERNEL, "%s-gpios", + mctrl_gpios_desc[i].name); + if (!device_property_present(dev, gpio_str)) + continue; if (mctrl_gpios_desc[i].dir_out) flags = GPIOD_OUT_LOW; -- 2.21.0