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=-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=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 92F35C43461 for ; Wed, 12 May 2021 15:15:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7421A6194D for ; Wed, 12 May 2021 15:15:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233792AbhELPPC (ORCPT ); Wed, 12 May 2021 11:15:02 -0400 Received: from mail.kernel.org ([198.145.29.99]:59262 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231216AbhELPFU (ORCPT ); Wed, 12 May 2021 11:05:20 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 6D1B661950; Wed, 12 May 2021 15:00:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1620831633; bh=78gEKsbijpXic+wdjychEXMDO/H2HEqJvvQxTkarXXQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=dQQbepNsQ06+XlB2ADSm49YS6gbylmv1/gXR6k0zi7pd94gb4eLCRb2U+3jgiEn0w E5+1nnmGAp7TevL3zCv+XVXzDh9HLu47Mrm2n6CqLie6hV/sOmx/qGl6Rx0sQ1JFCP y78HyaGGCjC1nQ9vYw1KSkwUwEARVWA1UlMTtWmQ= 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 5.4 164/244] mfd: stm32-timers: Avoid clearing auto reload register Date: Wed, 12 May 2021 16:48:55 +0200 Message-Id: <20210512144748.259378650@linuxfoundation.org> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210512144743.039977287@linuxfoundation.org> References: <20210512144743.039977287@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@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 efcd4b980c94..1adba6a46dcb 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 void stm32_timers_dma_probe(struct device *dev, -- 2.30.2