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 5B06DC88CB2 for ; Tue, 13 Jun 2023 08:59:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238653AbjFMI7A (ORCPT ); Tue, 13 Jun 2023 04:59:00 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33494 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234253AbjFMI7A (ORCPT ); Tue, 13 Jun 2023 04:59:00 -0400 Received: from relay5-d.mail.gandi.net (relay5-d.mail.gandi.net [IPv6:2001:4b98:dc4:8::225]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BBF11AA; Tue, 13 Jun 2023 01:58:56 -0700 (PDT) X-GND-Sasl: alexandre.belloni@bootlin.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=gm1; t=1686646735; 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=WzN2Ac9TNvZka8mc3EL6P/jfHd2/+XW2RC/3jQwoJKg=; b=a+aUakOpxVgNwgM7lSaedlXEVyRkC2GC35n5dYwYOKEhLAaRBuSkeQ8BZpHKzczjhjSWmf 9MdK8+JPRUiU+eB/MIHvbSY3zNnSFv5dFbRhMU9qcMWyCZIpqrKQ8zbJZzI5514TNey0W7 yOuxYCGCMVk0bT1rw30HzbxiAjq4mTfAtRyuAafFYVgY9mpW52Qq/W1XybiGf8HcDwsPJd 1mlCxI+mNOGUfiyqZCME5nd0jF7z/gsEYeqRlZPYBQ2QkEA5+nbHi2ivBmnGwQeSN7kqAI K5/QlnZox4mqqoV2EgaDMvmHyj3SFygyYhqL/BeOzMUr2WHe1uOrDAOtlgJ7rw== X-GND-Sasl: alexandre.belloni@bootlin.com X-GND-Sasl: alexandre.belloni@bootlin.com X-GND-Sasl: alexandre.belloni@bootlin.com X-GND-Sasl: alexandre.belloni@bootlin.com X-GND-Sasl: alexandre.belloni@bootlin.com X-GND-Sasl: alexandre.belloni@bootlin.com X-GND-Sasl: alexandre.belloni@bootlin.com X-GND-Sasl: alexandre.belloni@bootlin.com Received: by mail.gandi.net (Postfix) with ESMTPSA id 90AC81C000E; Tue, 13 Jun 2023 08:58:54 +0000 (UTC) Date: Tue, 13 Jun 2023 10:58:54 +0200 From: Alexandre Belloni To: Rasmus Villemoes Cc: Alessandro Zummo , Andy Shevchenko , devicetree@vger.kernel.org, Rob Herring , Krzysztof Kozlowski , Conor Dooley , linux-rtc@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 6/8] rtc: isl12022: trigger battery level detection during probe Message-ID: <2023061308585481c7cb97@mail.local> References: <20230612113059.247275-1-linux@rasmusvillemoes.dk> <20230612113059.247275-7-linux@rasmusvillemoes.dk> <20230612141518c2119835@mail.local> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org On 13/06/2023 09:44:55+0200, Rasmus Villemoes wrote: > On 12/06/2023 16.15, Alexandre Belloni wrote: > > On 12/06/2023 13:30:56+0200, Rasmus Villemoes wrote: > >> Since the meaning of the SR_LBAT85 and SR_LBAT75 bits are different in > >> battery backup mode, they may very well be set after power on, and > >> stay set for up to a minute (i.e. until the battery detection in VDD > >> mode happens when the seconds counter hits 59). This would mean that > >> userspace doing a ioctl(RTC_VL_READ) early on could get a false > >> positive. > >> > >> The battery level detection can also be triggered by explicitly > >> writing a 1 to the TSE bit in the BETA register. Do that once during > >> boot (well, probe), and emit a single warning to the kernel log if the > >> battery is already low. > >> > >> Signed-off-by: Rasmus Villemoes > >> --- > >> drivers/rtc/rtc-isl12022.c | 19 ++++++++++++++++++- > >> 1 file changed, 18 insertions(+), 1 deletion(-) > >> > >> diff --git a/drivers/rtc/rtc-isl12022.c b/drivers/rtc/rtc-isl12022.c > >> index 1b6659a9b33a..690dbb446d1a 100644 > >> --- a/drivers/rtc/rtc-isl12022.c > >> +++ b/drivers/rtc/rtc-isl12022.c > >> @@ -280,8 +280,25 @@ static void isl12022_set_trip_levels(struct device *dev) > >> mask = ISL12022_REG_VB85_MASK | ISL12022_REG_VB75_MASK; > >> > >> ret = regmap_update_bits(regmap, ISL12022_REG_PWR_VBAT, mask, val); > >> - if (ret) > >> + if (ret) { > >> dev_warn(dev, "unable to set battery alarm levels: %d\n", ret); > >> + return; > >> + } > >> + > >> + ret = regmap_write_bits(regmap, ISL12022_REG_BETA, > >> + ISL12022_BETA_TSE, ISL12022_BETA_TSE); > >> + if (ret) { > >> + dev_warn(dev, "unable to trigger battery level detection: %d\n", ret); > > > > This is too verbose, there is no action for the user upon getting this > > message. > > OK. > > > Setting TSE also enables temperature compensation, which may be an > > undesirable side effect. Shouldn't this be reverted if necessary? > > Well, I can't imagine the board designer not wanting/expecting > temperature compensation to be enabled since they've spent the $$ on > using a part with that capability. Also, we anyway set TSE if > CONFIG_HWMON so that the TEMP registers get updated once per minute. > > If you insist I'll do the proper logic to set it back to 0 if it wasn't > set beforehand, but I prefer to just keep it as-is. > Ok, fine > > > >> + return; > >> + } > >> + > >> + ret = isl12022_read_sr(regmap); > >> + if (ret < 0) { > >> + dev_warn(dev, "unable to read status register: %d\n", ret); > >> + } else if (ret & (ISL12022_SR_LBAT85 | ISL12022_SR_LBAT75)) { > >> + dev_warn(dev, "battery voltage is below %u%%\n", > >> + (ret & ISL12022_SR_LBAT75) ? 75 : 85); > > > > This message is useless, I'd drop the whole block. > > I only added this as "compensation" for ripping out the warning in 1/8, > since I assumed somebody actually wanted at least one warning in the > kernel log if the battery is low. > No need, I had a patch removing the message anyway. > I/we are not going to scrape dmesg but will use the ioctl() to monitor > the battery, so I'm perfectly happy to just remove this. That will also > make the question of how long to wait after setting TSE moot, since > certainly userspace won't be able to issue the ioctl() soon enough to > see stale values in the LBAT bits. > Exactly. > Rasmus > -- Alexandre Belloni, co-owner and COO, Bootlin Embedded Linux and Kernel engineering https://bootlin.com