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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,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 43228C31E45 for ; Thu, 13 Jun 2019 17:08:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 256B72063F for ; Thu, 13 Jun 2019 17:08:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2404578AbfFMRIH (ORCPT ); Thu, 13 Jun 2019 13:08:07 -0400 Received: from mga03.intel.com ([134.134.136.65]:41569 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729811AbfFMRIG (ORCPT ); Thu, 13 Jun 2019 13:08:06 -0400 X-Amp-Result: UNSCANNABLE X-Amp-File-Uploaded: False Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by orsmga103.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 13 Jun 2019 10:08:05 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.63,369,1557212400"; d="scan'208";a="184684275" Received: from smile.fi.intel.com (HELO smile) ([10.237.68.145]) by fmsmga002.fm.intel.com with ESMTP; 13 Jun 2019 10:08:03 -0700 Received: from andy by smile with local (Exim 4.92) (envelope-from ) id 1hbTCk-0006KB-GS; Thu, 13 Jun 2019 20:08:02 +0300 Date: Thu, 13 Jun 2019 20:08:02 +0300 From: Andy Shevchenko To: Stefan Roese Cc: linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org, Mika Westerberg , Yegor Yefremov , Greg Kroah-Hartman , Giulio Benetti Subject: Re: [PATCH 1/3 v6] serial: mctrl_gpio: Check if GPIO property exisits before requesting it Message-ID: <20190613170802.GE9224@smile.fi.intel.com> References: <20190613154542.32438-1-sr@denx.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190613154542.32438-1-sr@denx.de> Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 > Signed-off-by: Stefan Roese > Reviewed-by: Mika Westerberg > Cc: Mika Westerberg > Cc: Andy Shevchenko > Cc: Yegor Yefremov > Cc: Greg Kroah-Hartman > Cc: Giulio Benetti > --- > v6: > - No change > > v5: > - Simplified the code a bit (Andy) > - Added gpio_str == NULL handling (Andy) > > v4: > - Add missing free() calls (Johan) > - Added Mika's reviewed by tag > - Added Johan to Cc > > v3: > - No change > > v2: > - Include the problem description and analysis from Mika into the commit > text, as suggested by Greg. > > drivers/tty/serial/serial_mctrl_gpio.c | 13 +++++++++++++ > 1 file changed, 13 insertions(+) > > diff --git a/drivers/tty/serial/serial_mctrl_gpio.c b/drivers/tty/serial/serial_mctrl_gpio.c > index 39ed56214cd3..65348887a749 100644 > --- a/drivers/tty/serial/serial_mctrl_gpio.c > +++ b/drivers/tty/serial/serial_mctrl_gpio.c > @@ -116,6 +116,19 @@ 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; > + bool present; > + > + /* Check if GPIO property exists and continue if not */ > + gpio_str = kasprintf(GFP_KERNEL, "%s-gpios", > + mctrl_gpios_desc[i].name); > + if (!gpio_str) > + continue; > + > + present = device_property_present(dev, gpio_str); > + kfree(gpio_str); > + if (!present) > + continue; > > if (mctrl_gpios_desc[i].dir_out) > flags = GPIOD_OUT_LOW; > -- > 2.22.0 > -- With Best Regards, Andy Shevchenko