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=-8.3 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable 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 4D9D6C433E0 for ; Thu, 11 Jun 2020 10:09:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 217B420760 for ; Thu, 11 Jun 2020 10:09:33 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=st.com header.i=@st.com header.b="Dfg8Bh6V" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726917AbgFKKJc (ORCPT ); Thu, 11 Jun 2020 06:09:32 -0400 Received: from mx07-00178001.pphosted.com ([62.209.51.94]:31768 "EHLO mx07-00178001.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726965AbgFKKJc (ORCPT ); Thu, 11 Jun 2020 06:09:32 -0400 Received: from pps.filterd (m0046668.ppops.net [127.0.0.1]) by mx07-00178001.pphosted.com (8.16.0.42/8.16.0.42) with SMTP id 05BA7Lfr003767; Thu, 11 Jun 2020 12:09:17 +0200 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=st.com; h=subject : to : cc : references : from : message-id : date : mime-version : in-reply-to : content-type : content-transfer-encoding; s=STMicroelectronics; bh=io4QkYyPev1lFAk4WWD+YOdtfCEKcWGZV313SSMWam4=; b=Dfg8Bh6Vhx2dsVrLDsX09I4ViM0xyUXa6FCuXkjKTvZoDN/cXP4rVkspuAXlAku12pEI Nh8Zm+GNw16WVrhgo3hHmia75qDQ3oCHAMM01HT4+S+6AKbfYYu+rzKvB3oPbGIN/qRC FqipJob9rxIm5nv3I3lYnHW7rMETvn8k2EAHLiF3yS3w6WcWuEbs00aCMD5zSPUW3NcM B/huIlftPJ/ugddyWl+fFCILqYt/S8IFVenn+bdwJzp6UsuyiTBHvH9uvV5Gd9g+Q560 HehTAN2G8PXEM0hDDL26wzGEhB55ow48vko78kVKIZ7JOTLE1gEItLxlibEALYs85x6T 9w== Received: from beta.dmz-eu.st.com (beta.dmz-eu.st.com [164.129.1.35]) by mx07-00178001.pphosted.com with ESMTP id 31jppnyg1r-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 11 Jun 2020 12:09:17 +0200 Received: from euls16034.sgp.st.com (euls16034.sgp.st.com [10.75.44.20]) by beta.dmz-eu.st.com (STMicroelectronics) with ESMTP id 3B2C810002A; Thu, 11 Jun 2020 12:09:16 +0200 (CEST) Received: from Webmail-eu.st.com (sfhdag5node3.st.com [10.75.127.15]) by euls16034.sgp.st.com (STMicroelectronics) with ESMTP id F075B20F366; Thu, 11 Jun 2020 12:09:15 +0200 (CEST) Received: from [10.211.9.250] (10.75.127.45) by SFHDAG5NODE3.st.com (10.75.127.15) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Thu, 11 Jun 2020 12:09:14 +0200 Subject: Re: [PATCH v2] iio: adc: stm32-adc: fix runtime autosuspend delay when slow polling To: Jonathan Cameron , , CC: , , , , , , , References: <1588163348-31640-1-git-send-email-fabrice.gasnier@st.com> <20200503124811.0abf7655@archlinux> From: Fabrice Gasnier Message-ID: Date: Thu, 11 Jun 2020 12:09:12 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.8.0 MIME-Version: 1.0 In-Reply-To: <20200503124811.0abf7655@archlinux> Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.75.127.45] X-ClientProxiedBy: SFHDAG7NODE1.st.com (10.75.127.19) To SFHDAG5NODE3.st.com (10.75.127.15) X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.216,18.0.687 definitions=2020-06-11_10:2020-06-10,2020-06-11 signatures=0 Sender: linux-iio-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-iio@vger.kernel.org On 5/3/20 1:48 PM, Jonathan Cameron wrote: > On Wed, 29 Apr 2020 14:29:08 +0200 > Fabrice Gasnier wrote: > >> When the ADC is runtime suspended and starting a conversion, the stm32-adc >> driver calls pm_runtime_get_sync() that gets cascaded to the parent >> (e.g. runtime resume of stm32-adc-core driver). This also kicks the >> autosuspend delay (e.g. 2s) of the parent. >> Once the ADC is active, calling pm_runtime_get_sync() again (upon a new >> capture) won't kick the autosuspend delay for the parent (stm32-adc-core >> driver) as already active. >> >> Currently, this makes the stm32-adc-core driver go in suspend state >> every 2s when doing slow polling. As an example, doing a capture, e.g. >> cat in_voltageY_raw at a 0.2s rate, the auto suspend delay for the parent >> isn't refreshed. Once it expires, the parent immediately falls into >> runtime suspended state, in between two captures, as soon as the child >> driver falls into runtime suspend state: >> - e.g. after 2s, + child calls pm_runtime_put_autosuspend() + 100ms >> autosuspend delay of the child. >> - stm32-adc-core switches off regulators, clocks and so on. >> - They get switched on back again 100ms later in this example (at 2.2s). >> >> So, use runtime_idle() callback in stm32-adc-core driver to call >> pm_runtime_mark_last_busy() for the parent driver (stm32-adc-core), >> to avoid this. >> >> Fixes: 9bdbb1139ca1 ("iio: adc: stm32-adc: add power management support") >> >> Signed-off-by: Fabrice Gasnier > > Whilst this seems 'sensible' to me, I really don't have a good enough grasp > of runtime pm to be sure. > > I see something similar looking in the greybus driver, but not sure on the > reason it is there. > > Hence, ideally looking for an ack from Rafael on this one! Hi, Gentle reminder, I'm not sure how to progress on this patch. Rafael, or maybe Ulf, could take a look at it ? Thanks in advance, Best Regards, Fabrice > > Thanks, > > Jonathan > >> --- >> Changes in v2: >> - Use runtime_idle callback in stm32-adc-core driver, instead of refreshing >> last_busy from the child (for the parent) at many place. Initial patch v1 >> looked like "somewhat adhoc solution" as commented by Jonathan. >> --- >> drivers/iio/adc/stm32-adc-core.c | 9 ++++++++- >> 1 file changed, 8 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/iio/adc/stm32-adc-core.c b/drivers/iio/adc/stm32-adc-core.c >> index 2df88d2..ebe5dbc 100644 >> --- a/drivers/iio/adc/stm32-adc-core.c >> +++ b/drivers/iio/adc/stm32-adc-core.c >> @@ -803,6 +803,13 @@ static int stm32_adc_core_runtime_resume(struct device *dev) >> { >> return stm32_adc_core_hw_start(dev); >> } >> + >> +static int stm32_adc_core_runtime_idle(struct device *dev) >> +{ >> + pm_runtime_mark_last_busy(dev); >> + >> + return 0; >> +} >> #endif >> >> static const struct dev_pm_ops stm32_adc_core_pm_ops = { >> @@ -810,7 +817,7 @@ static const struct dev_pm_ops stm32_adc_core_pm_ops = { >> pm_runtime_force_resume) >> SET_RUNTIME_PM_OPS(stm32_adc_core_runtime_suspend, >> stm32_adc_core_runtime_resume, >> - NULL) >> + stm32_adc_core_runtime_idle) >> }; >> >> static const struct stm32_adc_priv_cfg stm32f4_adc_priv_cfg = { >