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 B16A3C77B75 for ; Fri, 5 May 2023 11:31:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231634AbjEELbw (ORCPT ); Fri, 5 May 2023 07:31:52 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40468 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231744AbjEELbv (ORCPT ); Fri, 5 May 2023 07:31:51 -0400 Received: from relay1-d.mail.gandi.net (relay1-d.mail.gandi.net [IPv6:2001:4b98:dc4:8::221]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B17ACF2 for ; Fri, 5 May 2023 04:31:49 -0700 (PDT) Received: (Authenticated sender: alexandre.belloni@bootlin.com) by mail.gandi.net (Postfix) with ESMTPSA id 086E7240012; Fri, 5 May 2023 11:31:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=gm1; t=1683286308; 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=NffZQWuckCG77Xp/zKqPn00BHHj5mEDr3UweS2YEfIw=; b=CI/QCHRgmeQKCvH5kEq1G7NuKLWSxvxNMEDPN0E81kfjoy8B+KBnwX2xt2ixNKggTL7zy1 owxMxCKXVgxO+Tgy8KQKyti+Wi7jXonvv3GC1qSYdeZCDbagV40R8HjdLtxUbQQb7rMnvs tMTpmFi8Sf5ORZSx+Qy4GXpJjtH9SBqMTdBtR75BzWewjkQBHri6xNWR5OZtCxiQMq3k+9 C+QJSbbYZNfZythlQVfDkR5lKRXcfGA3P2ubvVLyDOSPvjOEV5GbONwHzeLoV1JulWRbm5 K4YECLVsm6qa/kf0iKNbIIRnNOlmaN8XhLme2PlvcFxNEUE1YJL0rDz1lB86Zg== Date: Fri, 5 May 2023 13:31:47 +0200 From: Alexandre Belloni To: Johannes Kirchmair Cc: "linux-rtc@vger.kernel.org" Subject: Re: [PATCH] disable clkout for rv3028 by default Message-ID: <20230505113147f5967bca@mail.local> References: <20230504083217.2371933-1-johannes.kirchmair@sigmatek.at> <202305040912507451f5a2@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: linux-rtc@vger.kernel.org On 05/05/2023 10:31:38+0000, Johannes Kirchmair wrote: > Hello Alex, > > > -----Original Message----- > > From: Alexandre Belloni > > Sent: Donnerstag, 4. Mai 2023 11:13 > > To: Johannes Kirchmair > > Cc: linux-rtc@vger.kernel.org > > Subject: Re: [PATCH] disable clkout for rv3028 by default > > > > CAUTION: External E-Mail ! > > > > On 04/05/2023 10:32:17+0200, Johannes Kirchmair wrote: > > > The rv3028 chip is kind of strange. > > > The chip has two inputs one for the buffer battery > > > (V_backup) and one for the main power supply (V_dd). > > > By default a clk out of the chip is enabled, drawing a big amount of > > > current, draining the buffer battery of our board in 3 days. > > > There is a mode that would shut down the clk out if powered from > > > V_backup, but that would have to be configured as well. In our > > > application the battery is connected via V_dd. So disabling the clk by > > > default is the way to go for us. > > > > > > > You can't do that, this introduces a glitch in the clock output and will > > break existing users. The clock should be disabled automatically by the > > CCF when there are no users. Is your kernel built without > > CONFIG_COMMON_CLK > Now I am a little confused. > I tested on an x86 board where the clock was not disabled by the kernel. > Than I tested on an arm imx8 board where it was disabled by default. > > In both cases I used an 5.15 kernel. > > Difference between x86 and arm is, that in x86 we probe from user space after boot process and on the arm board the rtc is probed while booting. > > Do you know at what point the clock is disabled? Is it part of registering the clock? > This is clk_disable_unused which is a late_initcall_sync() > Best regards Johannes > > > > > > Signed-off-by: Johannes Kirchmair > > > --- > > > drivers/rtc/rtc-rv3028.c | 12 +++++++++++- > > > 1 file changed, 11 insertions(+), 1 deletion(-) > > > > > > diff --git a/drivers/rtc/rtc-rv3028.c b/drivers/rtc/rtc-rv3028.c > > > index 12c807306893..9e2aaa7a533e 100644 > > > --- a/drivers/rtc/rtc-rv3028.c > > > +++ b/drivers/rtc/rtc-rv3028.c > > > @@ -787,7 +787,7 @@ static const struct regmap_config regmap_config = { > > > static int rv3028_probe(struct i2c_client *client) > > > { > > > struct rv3028_data *rv3028; > > > - int ret, status; > > > + int ret, status, buf; > > > u32 ohms; > > > struct nvmem_config nvmem_cfg = { > > > .name = "rv3028_nvram", > > > @@ -826,6 +826,16 @@ static int rv3028_probe(struct i2c_client *client) > > > if (status & RV3028_STATUS_AF) > > > dev_warn(&client->dev, "An alarm may have been missed.\n"); > > > > > > + ret = regmap_read(rv3028->regmap, RV3028_CLKOUT, &buf); > > > + if (ret < 0) > > > + return ret; > > > + > > > + if (buf != RV3028_CLKOUT_FD_MASK) { > > > + ret = rv3028_update_cfg(rv3028, RV3028_CLKOUT, 0xff, > > RV3028_CLKOUT_FD_MASK); // disable clk out > > > + if (ret < 0) > > > + return ret; > > > + } > > > + > > > rv3028->rtc = devm_rtc_allocate_device(&client->dev); > > > if (IS_ERR(rv3028->rtc)) > > > return PTR_ERR(rv3028->rtc); > > > -- > > > 2.25.1 > > > > > > > -- > > Alexandre Belloni, co-owner and COO, Bootlin > > Embedded Linux and Kernel engineering > > https://bootlin.com -- Alexandre Belloni, co-owner and COO, Bootlin Embedded Linux and Kernel engineering https://bootlin.com