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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 82DA2C433F5 for ; Fri, 7 Oct 2022 18:57:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229648AbiJGS5s (ORCPT ); Fri, 7 Oct 2022 14:57:48 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37188 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229513AbiJGS5o (ORCPT ); Fri, 7 Oct 2022 14:57:44 -0400 Received: from relay4-d.mail.gandi.net (relay4-d.mail.gandi.net [217.70.183.196]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7D4E59F758; Fri, 7 Oct 2022 11:57:42 -0700 (PDT) Received: (Authenticated sender: alexandre.belloni@bootlin.com) by mail.gandi.net (Postfix) with ESMTPSA id 99517E0002; Fri, 7 Oct 2022 18:57:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=gm1; t=1665169060; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=iqBW2CwPxuqJw20irWWxJEKN6J5WBAj+ycFaQ0mdrf8=; b=br9j/u8pRrPuAON2MA6foE9JwLxCHNIbtr+cWeaZgAOYc8KZX2CIqmdgn1KmVY9zkf9IkL mRLkz33QOO+e0J5exw/Raa3dhMBVId5WIozRJkycxOpAJApcijLv2KmVMZXgs4LYhacLg8 lmyxboqeter8PDQfzJ26Fp7p8BM888D94cF7aett03kg8fC4E3rNcidYvj2izNgwEs/zat Bnpb1LctKgZnMwDk4zyUUifKzM4CnaD+6kGDhtbvo6Wmv9OUtsQsrr6VDLJxpsRTjtNqN4 i2Hav/uDnjbbz31v5CrCwNmDNInn450JvenUm4kg6ugmRNSdKVFoFcz5uRvo1g== Date: Fri, 7 Oct 2022 20:57:40 +0200 From: Alexandre Belloni To: Sean Anderson Cc: Alessandro Zummo , linux-rtc@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] rtc: abx80x: Don't warn about oscillator failure after PoR Message-ID: References: <20221007163712.2193966-1-sean.anderson@seco.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20221007163712.2193966-1-sean.anderson@seco.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On 07/10/2022 12:37:12-0400, Sean Anderson wrote: > According to the datasheet, the "oscillator failure" bit is set > > > ...on a power on reset, when both the system and battery voltages have > > dropped below acceptable levels. It is also set if an Oscillator Failure > > occurs.... > > From testing, this bit is also set if a software reset is initiated. > > This bit has a confusing name; it really tells us whether the time data > is valid. We clear it when writing the time. If it is still set, that > means there is a persistent issue (such as an oscillator failure), > instead of a transient one (such as power loss). > > Because there are several other reasons which might cause this bit > to be set (including booting for the first time or a battery failure), > do not warn about oscillator failures willy-nilly. This may cause system > integrators to waste time looking into the wrong line of investigation. > > Signed-off-by: Sean Anderson > --- > > drivers/rtc/rtc-abx80x.c | 17 ++++++++++++++++- > 1 file changed, 16 insertions(+), 1 deletion(-) > > diff --git a/drivers/rtc/rtc-abx80x.c b/drivers/rtc/rtc-abx80x.c > index 9b0138d07232..1eb752e4e39d 100644 > --- a/drivers/rtc/rtc-abx80x.c > +++ b/drivers/rtc/rtc-abx80x.c > @@ -115,6 +115,7 @@ struct abx80x_priv { > struct rtc_device *rtc; > struct i2c_client *client; > struct watchdog_device wdog; > + bool wrote_time; > }; > > static int abx80x_write_config_key(struct i2c_client *client, u8 key) > @@ -167,6 +168,7 @@ static int abx80x_enable_trickle_charger(struct i2c_client *client, > static int abx80x_rtc_read_time(struct device *dev, struct rtc_time *tm) > { > struct i2c_client *client = to_i2c_client(dev); > + struct abx80x_priv *priv = i2c_get_clientdata(client); > unsigned char buf[8]; > int err, flags, rc_mode = 0; > > @@ -181,7 +183,18 @@ static int abx80x_rtc_read_time(struct device *dev, struct rtc_time *tm) > return flags; > > if (flags & ABX8XX_OSS_OF) { > - dev_err(dev, "Oscillator failure, data is invalid.\n"); Simply remove the line. > + /* > + * The OF bit can be set either because of a reset > + * (PoR/Software reset) or because of an oscillator > + * failure. Effectively, it indicates that the stored > + * time is invalid. When we write the time, we clear > + * this bit. If it stays set, then this indicates an > + * oscillator failure. > + */ > + if (priv->wrote_time) > + dev_err(dev, "Oscillator failure\n"); > + else > + dev_info(dev, "Time data invalid\n"); > return -EINVAL; > } > } > @@ -207,6 +220,7 @@ static int abx80x_rtc_read_time(struct device *dev, struct rtc_time *tm) > static int abx80x_rtc_set_time(struct device *dev, struct rtc_time *tm) > { > struct i2c_client *client = to_i2c_client(dev); > + struct abx80x_priv *priv = i2c_get_clientdata(client); > unsigned char buf[8]; > int err, flags; > > @@ -240,6 +254,7 @@ static int abx80x_rtc_set_time(struct device *dev, struct rtc_time *tm) > dev_err(&client->dev, "Unable to write oscillator status register\n"); > return err; > } > + priv->wrote_time = true; > > return 0; > } > -- > 2.35.1.1320.gc452695387.dirty > -- Alexandre Belloni, co-owner and COO, Bootlin Embedded Linux and Kernel engineering https://bootlin.com