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=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham 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 AD0B3C18E5C for ; Tue, 10 Mar 2020 13:03:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6BB6824695 for ; Tue, 10 Mar 2020 13:03:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1583845395; bh=kcMAhrmYVfHyP3SFva/+apQupWoPVqUiqfIfT353oAU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=x0zbxAdHjSY0pJ5kYOJhji2CyPy3KSIFnG/Z57UihdALPQlLu5RYmSl8DexACVRVD JIlBbzKmODPbhPKtUy5UQfJWBV82MOINLRAAjqMck4Jp2zHQJ1CoaYoscFrbJTLvL2 o9o0B1DhbdIRX0UiZ6ctJa/oLt8Te6iuBT7OS370= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730549AbgCJNDO (ORCPT ); Tue, 10 Mar 2020 09:03:14 -0400 Received: from mail.kernel.org ([198.145.29.99]:47724 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730542AbgCJNDK (ORCPT ); Tue, 10 Mar 2020 09:03:10 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 4C419208E4; Tue, 10 Mar 2020 13:03:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1583845389; bh=kcMAhrmYVfHyP3SFva/+apQupWoPVqUiqfIfT353oAU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=DLZ15p59Q/EYHD5ifho9jtbF0sox0iEp5oIllctHtqZqaLisSWUFfMx259PaIQqMA H2tyGh2KGV5ugFEo9o4UxkADbzXhhKcDObsQhiCrj5CoDvXf+K5lBfNR+AhkeKJZPp 0dG937ow11fjct8dftblYvA2vMqyLHaLRE+cAO/w= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Fabrice Gasnier , Mark Brown Subject: [PATCH 5.5 166/189] regulator: stm32-vrefbuf: fix a possible overshoot when re-enabling Date: Tue, 10 Mar 2020 13:40:03 +0100 Message-Id: <20200310123656.755785851@linuxfoundation.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200310123639.608886314@linuxfoundation.org> References: <20200310123639.608886314@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Fabrice Gasnier commit 02fbabd5f4ed182d2c616e49309f5a3efd9ec671 upstream. There maybe an overshoot, when disabling, then re-enabling vrefbuf too quickly. VREFBUF is used by ADC/DAC on some boards. When re-enabling too quickly, an overshoot on the reference voltage make the conversions inaccurate for a short period of time. - Don't put the VREFBUF in HiZ when disabling, to force an active discharge. - Enforce a 1ms OFF/ON delay Fixes: 0cdbf481e927 ("regulator: Add support for stm32-vrefbuf") Signed-off-by: Fabrice Gasnier Message-Id: <1583312132-20932-1-git-send-email-fabrice.gasnier@st.com> Signed-off-by: Mark Brown Signed-off-by: Greg Kroah-Hartman --- drivers/regulator/stm32-vrefbuf.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/drivers/regulator/stm32-vrefbuf.c +++ b/drivers/regulator/stm32-vrefbuf.c @@ -88,7 +88,7 @@ static int stm32_vrefbuf_disable(struct } val = readl_relaxed(priv->base + STM32_VREFBUF_CSR); - val = (val & ~STM32_ENVR) | STM32_HIZ; + val &= ~STM32_ENVR; writel_relaxed(val, priv->base + STM32_VREFBUF_CSR); pm_runtime_mark_last_busy(priv->dev); @@ -175,6 +175,7 @@ static const struct regulator_desc stm32 .volt_table = stm32_vrefbuf_voltages, .n_voltages = ARRAY_SIZE(stm32_vrefbuf_voltages), .ops = &stm32_vrefbuf_volt_ops, + .off_on_delay = 1000, .type = REGULATOR_VOLTAGE, .owner = THIS_MODULE, };