From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from lindbergh.monkeyblade.net (lindbergh.monkeyblade.net [23.128.96.19]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C99291DFDA for ; Tue, 10 Oct 2023 13:40:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=none Received: from metis.whiteo.stw.pengutronix.de (metis.whiteo.stw.pengutronix.de [IPv6:2a0a:edc0:2:b01:1d::104]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 12FF610E7 for ; Tue, 10 Oct 2023 06:39:49 -0700 (PDT) Received: from drehscheibe.grey.stw.pengutronix.de ([2a0a:edc0:0:c01:1d::a2]) by metis.whiteo.stw.pengutronix.de with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1qqCxU-0007N7-9E; Tue, 10 Oct 2023 15:39:36 +0200 Received: from [2a0a:edc0:2:b01:1d::c0] (helo=ptx.whiteo.stw.pengutronix.de) by drehscheibe.grey.stw.pengutronix.de with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1qqCxT-000g0g-CR; Tue, 10 Oct 2023 15:39:35 +0200 Received: from ore by ptx.whiteo.stw.pengutronix.de with local (Exim 4.92) (envelope-from ) id 1qqCxT-00Dk78-9t; Tue, 10 Oct 2023 15:39:35 +0200 Date: Tue, 10 Oct 2023 15:39:35 +0200 From: Oleksij Rempel To: Mark Brown Cc: Liam Girdwood , Rob Herring , Krzysztof Kozlowski , Conor Dooley , kernel@pengutronix.de, linux-kernel@vger.kernel.org, devicetree@vger.kernel.org Subject: Re: [PATCH v1 3/3] regulator: fixed: forward under-voltage events Message-ID: <20231010133935.GB3268051@pengutronix.de> References: <20231010085906.3440452-1-o.rempel@pengutronix.de> <20231010085906.3440452-3-o.rempel@pengutronix.de> <5e51792a-cc93-4364-a51b-c2b116d89369@sirena.org.uk> <20231010125531.GA3268051@pengutronix.de> Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20231010125531.GA3268051@pengutronix.de> X-Sent-From: Pengutronix Hildesheim X-URL: http://www.pengutronix.de/ X-Accept-Language: de,en X-Accept-Content-Type: text/plain User-Agent: Mutt/1.10.1 (2018-07-13) X-SA-Exim-Connect-IP: 2a0a:edc0:0:c01:1d::a2 X-SA-Exim-Mail-From: ore@pengutronix.de X-SA-Exim-Scanned: No (on metis.whiteo.stw.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: devicetree@vger.kernel.org X-Spam-Status: No, score=-2.6 required=5.0 tests=BAYES_00,RCVD_IN_DNSWL_LOW, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net On Tue, Oct 10, 2023 at 02:55:31PM +0200, Oleksij Rempel wrote: > Hi, > > On Tue, Oct 10, 2023 at 01:19:36PM +0100, Mark Brown wrote: > > On Tue, Oct 10, 2023 at 10:59:06AM +0200, Oleksij Rempel wrote: > > > Add handler to forward under-voltage events. > > > On systems for more or less complicated regulator chains we need to > > > forward under-voltage events to actual driver which need to react on > > > them. > > > > It isn't clear to me why this would be implemented in one specific > > driver, nor why this would be done unconditionally. Could you provide > > some information on the problem you're trying to solve here? > > The hardware I am working with has an under-voltage sensor on the 24V > supply regulator and some backup capacitors to run SoC for 100ms. I want > to forward under-voltage events across a chain of different regulators > to a designated consumer. For instance, to the mmc driver, enabling it > to initiate shutdown before power loss occurs. Additionally, a bit can > be set in the volatile memory of a scratch pad in an RTC clock to record > sudden power loss, which can be checked on the next system start. The bit picture of my HW may potentially be even more advanced: - some regulator chain paths are disabled by the HW. With other words under-voltage event is converted to fail or disable. There is nothing what software can do, but it will be good to reflect it on the SW side for diagnostic. - some paths can be disabled by software to get some more milliseconds of life and complete emergency shutdown task. -- Pengutronix e.K. | | Steuerwalder Str. 21 | http://www.pengutronix.de/ | 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |