From patchwork Wed May 12 14:47:31 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 436617 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=-19.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, 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 55AB7C43460 for ; Wed, 12 May 2021 16:27:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C726C61026 for ; Wed, 12 May 2021 16:27:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236923AbhELQXf (ORCPT ); Wed, 12 May 2021 12:23:35 -0400 Received: from mail.kernel.org ([198.145.29.99]:51344 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237834AbhELQN0 (ORCPT ); Wed, 12 May 2021 12:13:26 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 07F4A619A9; Wed, 12 May 2021 15:41:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1620834101; bh=mW3nM8JiIx1PdIRU+c4FabPHmHJaWAl+9/gSo3NoC14=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=UXP5gOFeKCQwNqvo/YS82OWA4et/mYnGyATW26y5wSQzKNv7JE/XnnNclPg5p4A6B aomcoZwXDPjMFSidQsztRn6xUi54Bj3JFf4Vbh5wer8YRG7J1EtG27qgiYMj2uBVq+ FrEV2PS38hAR/uAzXGuM519e9o83iKfykc5jfIuw= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Fabrice Gasnier , William Breathitt Gray , Lee Jones , Sasha Levin Subject: [PATCH 5.11 374/601] mfd: stm32-timers: Avoid clearing auto reload register Date: Wed, 12 May 2021 16:47:31 +0200 Message-Id: <20210512144840.112235220@linuxfoundation.org> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210512144827.811958675@linuxfoundation.org> References: <20210512144827.811958675@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Fabrice Gasnier [ Upstream commit 4917e498c6894ba077867aff78f82cffd5ffbb5c ] The ARR register is cleared unconditionally upon probing, after the maximum value has been read. This initial condition is rather not intuitive, when considering the counter child driver. It rather expects the maximum value by default: - The counter interface shows a zero value by default for 'ceiling' attribute. - Enabling the counter without any prior configuration makes it doesn't count. The reset value of ARR register is the maximum. So Choice here is to backup it, and restore it then, instead of clearing its value. It also fixes the initial condition seen by the counter driver. Fixes: d0f949e220fd ("mfd: Add STM32 Timers driver") Signed-off-by: Fabrice Gasnier Acked-by: William Breathitt Gray Signed-off-by: Lee Jones Signed-off-by: Sasha Levin --- drivers/mfd/stm32-timers.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/drivers/mfd/stm32-timers.c b/drivers/mfd/stm32-timers.c index add603359124..44ed2fce0319 100644 --- a/drivers/mfd/stm32-timers.c +++ b/drivers/mfd/stm32-timers.c @@ -158,13 +158,18 @@ static const struct regmap_config stm32_timers_regmap_cfg = { static void stm32_timers_get_arr_size(struct stm32_timers *ddata) { + u32 arr; + + /* Backup ARR to restore it after getting the maximum value */ + regmap_read(ddata->regmap, TIM_ARR, &arr); + /* * Only the available bits will be written so when readback * we get the maximum value of auto reload register */ regmap_write(ddata->regmap, TIM_ARR, ~0L); regmap_read(ddata->regmap, TIM_ARR, &ddata->max_arr); - regmap_write(ddata->regmap, TIM_ARR, 0x0); + regmap_write(ddata->regmap, TIM_ARR, arr); } static int stm32_timers_dma_probe(struct device *dev,