From patchwork Wed Jul 1 14:55:28 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Fabrice Gasnier X-Patchwork-Id: 11636593 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id C394013BD for ; Wed, 1 Jul 2020 14:56:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AABAC20702 for ; Wed, 1 Jul 2020 14:56:30 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=st.com header.i=@st.com header.b="wpXgP/rp" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727014AbgGAO4a (ORCPT ); Wed, 1 Jul 2020 10:56:30 -0400 Received: from mx07-00178001.pphosted.com ([62.209.51.94]:42046 "EHLO mx07-00178001.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726854AbgGAO43 (ORCPT ); Wed, 1 Jul 2020 10:56:29 -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 061EtrS5003069; Wed, 1 Jul 2020 16:56:11 +0200 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=st.com; h=from : to : cc : subject : date : message-id : mime-version : content-type; s=STMicroelectronics; bh=nGDxePmF8IHyOLxj56WyGmH8rDztYQ7/Xj77p7TVsIY=; b=wpXgP/rpD0IANM8/tkoEOdkQWEETKMnvIvHdvYz/RnTNlb/T9hYWhL/hRDfBxv8YFH/g q0pcI2muFSjnAz89Zjo6N3lL1hZpAkjfYj8kevyScHcluxdmTEDW05zjQciBmBcxr4wR O4MhmBrZZT46RR5YuFouOnSL2usw1wHaDvrHKzKHtWtkOLNclPEjCiZO3b0xVMwvG7Zy L3FNKVzXsCmTpk2tpDh1v5S4scfP48xfXDozmU7kqAisBH+mcX79tA68FBB7zVWlSsbe yW8HHdy0eoVr9uEBDqdcHSFtRvHlFo7D4HeEGKZyyNA9f2G3LKcv2C8iT4dUYhE7glVN cg== Received: from beta.dmz-eu.st.com (beta.dmz-eu.st.com [164.129.1.35]) by mx07-00178001.pphosted.com with ESMTP id 31wuk1jsy0-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 01 Jul 2020 16:56:11 +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 1F6E210002A; Wed, 1 Jul 2020 16:56:10 +0200 (CEST) Received: from Webmail-eu.st.com (sfhdag5node3.st.com [10.75.127.15]) by euls16034.sgp.st.com (STMicroelectronics) with ESMTP id 0F0502BE22C; Wed, 1 Jul 2020 16:56:10 +0200 (CEST) Received: from localhost (10.75.127.44) by SFHDAG5NODE3.st.com (10.75.127.15) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Wed, 1 Jul 2020 16:56:09 +0200 From: Fabrice Gasnier To: , CC: , , , , , , , , , Subject: [RESEND PATCH v2] iio: adc: stm32-adc: fix runtime autosuspend delay when slow polling Date: Wed, 1 Jul 2020 16:55:28 +0200 Message-ID: <1593615328-5180-1-git-send-email-fabrice.gasnier@st.com> X-Mailer: git-send-email 2.7.4 MIME-Version: 1.0 X-Originating-IP: [10.75.127.44] X-ClientProxiedBy: SFHDAG3NODE1.st.com (10.75.127.7) To SFHDAG5NODE3.st.com (10.75.127.15) X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.235,18.0.687 definitions=2020-07-01_08:2020-07-01,2020-07-01 signatures=0 Sender: linux-iio-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-iio@vger.kernel.org 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 Reviewed-by: Ulf Hansson --- 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 0e2068e..3586369 100644 --- a/drivers/iio/adc/stm32-adc-core.c +++ b/drivers/iio/adc/stm32-adc-core.c @@ -794,6 +794,13 @@ 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 = { @@ -801,7 +808,7 @@ 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 = {