From patchwork Fri Jun 19 14:34:28 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 224035 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,URIBL_BLOCKED,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 BAD95C433E0 for ; Fri, 19 Jun 2020 15:33:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 96CFD20786 for ; Fri, 19 Jun 2020 15:33:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1592580835; bh=thQfZr/q8RAdyDUbyWCNv25/gg/BpfzE787BTka3u6c=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=XKlHvDDaFQRnO2ubWacv5scGdhefyHkuzQLCvCPLJ3gJDoEpsL9Wpa21hjMQW3WR0 b78tCvwHEBXVvzMifTMVNJFy30J5k+BTD2ejDX6JMFI19Gidtspx3bhHMETOdJkbv1 xClsBvrcnpIZFkw3WKyIgRjO9EdP11cQHBvKEJls= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2403876AbgFSPdy (ORCPT ); Fri, 19 Jun 2020 11:33:54 -0400 Received: from mail.kernel.org ([198.145.29.99]:37050 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2404895AbgFSPdD (ORCPT ); Fri, 19 Jun 2020 11:33:03 -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 A984B2166E; Fri, 19 Jun 2020 15:33:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1592580782; bh=thQfZr/q8RAdyDUbyWCNv25/gg/BpfzE787BTka3u6c=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=An3xlAUc7TfD/GJVt6wTHmoNH2wkRHeSgIKerGjpFXsS0TWMJlIbgtW4E9bJQ0hf9 YRfCChW2PEcQdSbn9e0pCG0rKskRPWx0EF+doKaFz39fwhJcMAuu5PaPS9eCCYq+04 oOO0n26YgoHFHh/vMtvibrN88GZDzFq1iRGzbCRo= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Hans de Goede , Andy Shevchenko , Thierry Reding Subject: [PATCH 5.7 350/376] pwm: lpss: Fix get_state runtime-pm reference handling Date: Fri, 19 Jun 2020 16:34:28 +0200 Message-Id: <20200619141726.893185565@linuxfoundation.org> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20200619141710.350494719@linuxfoundation.org> References: <20200619141710.350494719@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Hans de Goede commit 01aa905d4791da7d3630f6030ff99d58105cca00 upstream. Before commit cfc4c189bc70 ("pwm: Read initial hardware state at request time"), a driver's get_state callback would get called once per PWM from pwmchip_add(). pwm-lpss' runtime-pm code was relying on this, getting a runtime-pm ref for PWMs which are enabled at probe time from within its get_state callback, before enabling runtime-pm. The change to calling get_state at request time causes a number of problems: 1. PWMs enabled at probe time may get runtime suspended before they are requested, causing e.g. a LCD backlight controlled by the PWM to turn off. 2. When the request happens when the PWM has been runtime suspended, the ctrl register will read all 1 / 0xffffffff, causing get_state to store bogus values in the pwm_state. 3. get_state was using an async pm_runtime_get() call, because it assumed that runtime-pm has not been enabled yet. If shortly after the request an apply call is made, then the pwm_lpss_is_updating() check may trigger because the resume triggered by the pm_runtime_get() call is not complete yet, so the ctrl register still reads all 1 / 0xffffffff. This commit fixes these issues by moving the initial pm_runtime_get() call for PWMs which are enabled at probe time to the pwm_lpss_probe() function; and by making get_state take a runtime-pm ref before reading the ctrl reg. BugLink: https://bugzilla.redhat.com/show_bug.cgi?id=1828927 Fixes: cfc4c189bc70 ("pwm: Read initial hardware state at request time") Cc: stable@vger.kernel.org Signed-off-by: Hans de Goede Reviewed-by: Andy Shevchenko Signed-off-by: Thierry Reding Signed-off-by: Greg Kroah-Hartman --- drivers/pwm/pwm-lpss.c | 15 +++++++++++---- 1 file changed, 11 insertions(+), 4 deletions(-) --- a/drivers/pwm/pwm-lpss.c +++ b/drivers/pwm/pwm-lpss.c @@ -158,7 +158,6 @@ static int pwm_lpss_apply(struct pwm_chi return 0; } -/* This function gets called once from pwmchip_add to get the initial state */ static void pwm_lpss_get_state(struct pwm_chip *chip, struct pwm_device *pwm, struct pwm_state *state) { @@ -167,6 +166,8 @@ static void pwm_lpss_get_state(struct pw unsigned long long base_unit, freq, on_time_div; u32 ctrl; + pm_runtime_get_sync(chip->dev); + base_unit_range = BIT(lpwm->info->base_unit_bits); ctrl = pwm_lpss_read(pwm); @@ -187,8 +188,7 @@ static void pwm_lpss_get_state(struct pw state->polarity = PWM_POLARITY_NORMAL; state->enabled = !!(ctrl & PWM_ENABLE); - if (state->enabled) - pm_runtime_get(chip->dev); + pm_runtime_put(chip->dev); } static const struct pwm_ops pwm_lpss_ops = { @@ -202,7 +202,8 @@ struct pwm_lpss_chip *pwm_lpss_probe(str { struct pwm_lpss_chip *lpwm; unsigned long c; - int ret; + int i, ret; + u32 ctrl; if (WARN_ON(info->npwm > MAX_PWMS)) return ERR_PTR(-ENODEV); @@ -232,6 +233,12 @@ struct pwm_lpss_chip *pwm_lpss_probe(str return ERR_PTR(ret); } + for (i = 0; i < lpwm->info->npwm; i++) { + ctrl = pwm_lpss_read(&lpwm->chip.pwms[i]); + if (ctrl & PWM_ENABLE) + pm_runtime_get(dev); + } + return lpwm; } EXPORT_SYMBOL_GPL(pwm_lpss_probe);