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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id AE342C64EC4 for ; Fri, 10 Mar 2023 15:15:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234123AbjCJPPx (ORCPT ); Fri, 10 Mar 2023 10:15:53 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56824 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234210AbjCJPPP (ORCPT ); Fri, 10 Mar 2023 10:15:15 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D8A21132A8C for ; Fri, 10 Mar 2023 07:06:31 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 565A861ACC for ; Fri, 10 Mar 2023 15:05:38 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 54E79C433EF; Fri, 10 Mar 2023 15:05:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1678460737; bh=vYKrF8LfbcEY50jVQyedLPtVAEhEDbWRjMx4/YkiO8E=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=dZowS2iyYZ2gJnR7uAiAtHT43Hk/nx3Zw03G+my3yXxZs7hdl4Aaf2utyzAuFVrVo 0BBByNadcMSzDPzYv4yQEVKeYh6yjREdM4nwPLFuhGw95+iSjDaQfUbhdzwIg3xBao KimMa3mz/WtNk/p4y3bpesdtRoh2gU5HHyLJM4/0= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, =?UTF-8?q?Uwe=20Kleine-K=C3=B6nig?= , Emil Renner Berthing , Thierry Reding , Sasha Levin Subject: [PATCH 5.10 434/529] pwm: sifive: Reduce time the controller lock is held Date: Fri, 10 Mar 2023 14:39:37 +0100 Message-Id: <20230310133825.028779564@linuxfoundation.org> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230310133804.978589368@linuxfoundation.org> References: <20230310133804.978589368@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Uwe Kleine-König [ Upstream commit 0f02f491b786143f08eb19840f1cf4f12aec6dee ] The lock is only to serialize access and update to user_count and approx_period between different PWMs served by the same pwm_chip. So the lock needs only to be taken during the check if the (chip global) period can and/or needs to be changed. Signed-off-by: Uwe Kleine-König Tested-by: Emil Renner Berthing Signed-off-by: Thierry Reding Stable-dep-of: 334c7b13d383 ("pwm: sifive: Always let the first pwm_apply_state succeed") Signed-off-by: Sasha Levin --- drivers/pwm/pwm-sifive.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/drivers/pwm/pwm-sifive.c b/drivers/pwm/pwm-sifive.c index 12e9e23272ab1..400cc91057acf 100644 --- a/drivers/pwm/pwm-sifive.c +++ b/drivers/pwm/pwm-sifive.c @@ -41,7 +41,7 @@ struct pwm_sifive_ddata { struct pwm_chip chip; - struct mutex lock; /* lock to protect user_count */ + struct mutex lock; /* lock to protect user_count and approx_period */ struct notifier_block notifier; struct clk *clk; void __iomem *regs; @@ -76,6 +76,7 @@ static void pwm_sifive_free(struct pwm_chip *chip, struct pwm_device *pwm) mutex_unlock(&ddata->lock); } +/* Called holding ddata->lock */ static void pwm_sifive_update_clock(struct pwm_sifive_ddata *ddata, unsigned long rate) { @@ -163,7 +164,6 @@ static int pwm_sifive_apply(struct pwm_chip *chip, struct pwm_device *pwm, return ret; } - mutex_lock(&ddata->lock); cur_state = pwm->state; enabled = cur_state.enabled; @@ -182,14 +182,17 @@ static int pwm_sifive_apply(struct pwm_chip *chip, struct pwm_device *pwm, /* The hardware cannot generate a 100% duty cycle */ frac = min(frac, (1U << PWM_SIFIVE_CMPWIDTH) - 1); + mutex_lock(&ddata->lock); if (state->period != ddata->approx_period) { if (ddata->user_count != 1) { + mutex_unlock(&ddata->lock); ret = -EBUSY; goto exit; } ddata->approx_period = state->period; pwm_sifive_update_clock(ddata, clk_get_rate(ddata->clk)); } + mutex_unlock(&ddata->lock); writel(frac, ddata->regs + PWM_SIFIVE_PWMCMP(pwm->hwpwm)); @@ -198,7 +201,6 @@ static int pwm_sifive_apply(struct pwm_chip *chip, struct pwm_device *pwm, exit: clk_disable(ddata->clk); - mutex_unlock(&ddata->lock); return ret; } -- 2.39.2