From patchwork Tue Aug 15 10:43:29 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Leif Middelschulte X-Patchwork-Id: 1821324 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@legolas.ozlabs.org Authentication-Results: legolas.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org (client-ip=2620:137:e000::1:20; helo=out1.vger.email; envelope-from=linux-pwm-owner@vger.kernel.org; receiver=) Authentication-Results: legolas.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256 header.s=20221208 header.b=S/WIormd; dkim-atps=neutral Received: from out1.vger.email (out1.vger.email [IPv6:2620:137:e000::1:20]) by legolas.ozlabs.org (Postfix) with ESMTP id 4RQ7FC1l1Sz1yfb for ; Tue, 15 Aug 2023 20:44:47 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236439AbjHOKoL (ORCPT ); Tue, 15 Aug 2023 06:44:11 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59686 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236516AbjHOKnp (ORCPT ); Tue, 15 Aug 2023 06:43:45 -0400 Received: from mail-ej1-x62b.google.com (mail-ej1-x62b.google.com [IPv6:2a00:1450:4864:20::62b]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1764D199F; Tue, 15 Aug 2023 03:43:42 -0700 (PDT) Received: by mail-ej1-x62b.google.com with SMTP id a640c23a62f3a-99bf8e5ab39so715392366b.2; Tue, 15 Aug 2023 03:43:42 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20221208; t=1692096220; x=1692701020; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=izO0tZzm3QLcY+sUcTdrcBNTqHL831hXZtp+UuXI19g=; b=S/WIormd94u7em4MZjGUFv8zIwrpEoyaTwbXs+rlOhpgq4lFQBYGWilNdyZiFCd4Oc eOLIju7rRkIgqloXyVFSdcUj5Fet4XAXLWf/7HGUbx/mpqg9SPLBmLwacuef15Ave6vA 38hQUkZ+qKOk6WyPOMqa1fT3LKDNkA/iJpX6PjCOD/ALXzJwxiE8aPATuzpZbMtD8Rki R7ny3A6XVRQJ/So0+CZeN9VaIBVW0YaNNOsmJOaDrEmScgJW60fcx7J4Zvrvq3hFUW+3 /P8y+PVV07Ngfevc0la8N3s3oWjrSqFpsaRcdH2PQmpn9JFYyN+Uw7vyq0hrD6Iqi9y1 e+Aw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1692096220; x=1692701020; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=izO0tZzm3QLcY+sUcTdrcBNTqHL831hXZtp+UuXI19g=; b=YGy8PTlz8xEEUsjR5EAVXbXT9LXTxGZO7zCPGdW4viwAJsADYyzmYFyhs9HByzf1Ql K+R25+ZjaRS3tabJXCCb3Hh6IMLCpAo8xEG38HpFlNgtHkVtCCMwzO1RiniqiRSPXmQ1 ULep5M8kZCoPNOQjoVEj5l10ATLK26FiknXu9t2PNR1GF7IyM6Pm1AEvEeQBB7NGoaD2 2CN+p07VPJlzdgBPOBsji/nm0cyF/AfiSqQC4W5WVopifynWc6Wox0ho8o3naf1H1HZX ZpKfldVRenCVna+cWgeySWjQZJpocHnBChQ/5R0m339zVRIpUNYjj/BfpoS7RmkjCTaH PWCA== X-Gm-Message-State: AOJu0YxGNg/sEPo0N6cddQIS6CiwEBePcOZ6w/ju9f8iIuFINJI50l64 ceRQ1yFzrOAGAUnLSwoza6U= X-Google-Smtp-Source: AGHT+IEjn0TgKyCUAw/r/ZD1Yio4oGXG55KLp3wwLdcgB2uGZ7G7CxI+L1GmvoL+wV+Z6boGgz3n0g== X-Received: by 2002:a17:906:20d7:b0:99b:c949:5ef8 with SMTP id c23-20020a17090620d700b0099bc9495ef8mr10187701ejc.54.1692096220330; Tue, 15 Aug 2023 03:43:40 -0700 (PDT) Received: from localhost.localdomain (pd9e9e2b1.dip0.t-ipconnect.de. [217.233.226.177]) by smtp.gmail.com with ESMTPSA id md15-20020a170906ae8f00b0098d486d2bdfsm6944627ejb.177.2023.08.15.03.43.39 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Tue, 15 Aug 2023 03:43:39 -0700 (PDT) From: Leif Middelschulte X-Google-Original-From: Leif Middelschulte To: Thierry Reding , =?utf-8?q?Uwe_Kleine-K=C3=B6n?= =?utf-8?q?ig?= , Shawn Guo , Sascha Hauer , Pengutronix Kernel Team , Fabio Estevam , NXP Linux Team Cc: Leif Middelschulte , linux-pwm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: [PATCH v3 1/4] pwm: imx27: fix race condition .apply,.get_state Date: Tue, 15 Aug 2023 12:43:29 +0200 Message-Id: <20230815104332.55044-1-Leif.Middelschulte@gmail.com> X-Mailer: git-send-email 2.39.2 (Apple Git-143) In-Reply-To: <20230310174517.rb7xxrougkse2lrc@pengutronix.de> References: <20230310174517.rb7xxrougkse2lrc@pengutronix.de> MIME-Version: 1.0 X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,FREEMAIL_FROM, RCVD_IN_DNSWL_BLOCKED,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-pwm@vger.kernel.org From: Leif Middelschulte With CONFIG_PWM_DEBUG=y after writing a value to the PWMSAR register in .apply(), the register is read in .get_state(). Unless a period completed in the meantime, this read yields the previously used duty cycle configuration. As the PWM_DEBUG code applies the read out configuration for testing purposes this effectively undoes the intended effect by rewriting the previous hardware state. Note that this change merely implements a sensible heuristic. The i.MX has a 4 slot FIFO to configure the duty cycle. This FIFO cannot be read back in its entirety. The "write x then read back x from hw" semantics are therefore not easily applicable. With this change, the .get_state() function tries to wait for some stabilization in the FIFO (empty state). In this state it keeps applying the last value written to the sample register. Signed-off-by: Leif Middelschulte --- drivers/pwm/pwm-imx27.c | 50 ++++++++++++++++++++++++++++++++++++++--- 1 file changed, 47 insertions(+), 3 deletions(-) diff --git a/drivers/pwm/pwm-imx27.c b/drivers/pwm/pwm-imx27.c index 29a3089c534c..32389ca2da3e 100644 --- a/drivers/pwm/pwm-imx27.c +++ b/drivers/pwm/pwm-imx27.c @@ -75,6 +75,7 @@ (x)) + 1) #define MX3_PWM_SWR_LOOP 5 +#define MX3_PWM_FIFOAV_EMPTY_LOOP 4 /* PWMPR register value of 0xffff has the same effect as 0xfffe */ #define MX3_PWMPR_MAX 0xfffe @@ -118,8 +119,28 @@ static void pwm_imx27_clk_disable_unprepare(struct pwm_imx27_chip *imx) clk_disable_unprepare(imx->clk_ipg); } +static int pwm_imx27_wait_fifo_empty(struct pwm_chip *chip, + struct pwm_device *pwm) +{ + struct pwm_imx27_chip *imx = to_pwm_imx27_chip(chip); + struct device *dev = chip->dev; + unsigned int period_ms = DIV_ROUND_UP_ULL(pwm_get_period(pwm), NSEC_PER_MSEC); + int tries = MX3_PWM_FIFOAV_EMPTY_LOOP; + int fifoav; + u32 sr; + + while (tries--) { + sr = readl(imx->mmio_base + MX3_PWMSR); + fifoav = FIELD_GET(MX3_PWMSR_FIFOAV, sr); + if (fifoav == MX3_PWMSR_FIFOAV_EMPTY) + return; + msleep(period_ms); + } + dev_warn(dev, "FIFO has been refilled concurrently\n"); +} + static int pwm_imx27_get_state(struct pwm_chip *chip, - struct pwm_device *pwm, struct pwm_state *state) + struct pwm_device *pwm, struct pwm_state *state) { struct pwm_imx27_chip *imx = to_pwm_imx27_chip(chip); u32 period, prescaler, pwm_clk, val; @@ -161,10 +182,33 @@ static int pwm_imx27_get_state(struct pwm_chip *chip, * PWMSAR can be read only if PWM is enabled. If the PWM is disabled, * use the cached value. */ - if (state->enabled) + if (state->enabled) { + /* + * From the i.MX PWM reference manual: + * "A read on the sample register yields the current FIFO value that + * is being used, or will be used, by the PWM for generation on the + * output signal. Therefore, a write and a subsequent read on the + * sample register may result in different values being obtained." + * Furthermore: + * "When a new value is written, the duty cycle changes after the + * current period is over." + * Note "changes" vs. "changes to the given value"! + * Finally: + * "The PWM will run at the last set duty-cycle setting if all the + * values of the FIFO has been utilized, until the FIFO is reloaded + * or the PWM is disabled." + * Try to be at least a bit more deterministic about which value is + * read by waiting until the FIFO is empty. In this state the last/most + * recently pushed sample (duty cycle) value is continuously applied. + * Beware that this approach is still racy, as a new value could have + * been supplied and a period expired between the call of the wait + * function and the subsequent readl. + */ + pwm_imx27_wait_fifo_empty(chip, pwm); val = readl(imx->mmio_base + MX3_PWMSAR); - else + } else { val = imx->duty_cycle; + } tmp = NSEC_PER_SEC * (u64)(val) * prescaler; state->duty_cycle = DIV_ROUND_UP_ULL(tmp, pwm_clk); From patchwork Tue Aug 15 10:43:30 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Leif Middelschulte X-Patchwork-Id: 1821325 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@legolas.ozlabs.org Authentication-Results: legolas.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org (client-ip=2620:137:e000::1:20; helo=out1.vger.email; envelope-from=linux-pwm-owner@vger.kernel.org; receiver=) Authentication-Results: legolas.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256 header.s=20221208 header.b=BVKJ4NC6; dkim-atps=neutral Received: from out1.vger.email (out1.vger.email [IPv6:2620:137:e000::1:20]) by legolas.ozlabs.org (Postfix) with ESMTP id 4RQ7FC46jTz1ygB for ; Tue, 15 Aug 2023 20:44:47 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236467AbjHOKoN (ORCPT ); Tue, 15 Aug 2023 06:44:13 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34332 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236542AbjHOKnx (ORCPT ); Tue, 15 Aug 2023 06:43:53 -0400 Received: from mail-lj1-x22e.google.com (mail-lj1-x22e.google.com [IPv6:2a00:1450:4864:20::22e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8E3201999; Tue, 15 Aug 2023 03:43:45 -0700 (PDT) Received: by mail-lj1-x22e.google.com with SMTP id 38308e7fff4ca-2b9b50be31aso78565441fa.3; Tue, 15 Aug 2023 03:43:45 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20221208; t=1692096224; x=1692701024; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=AYPNsi1tl/0GDFSQd4trv1IQAjRIoOCldAj6utrHW9I=; b=BVKJ4NC6xl0b1hX2so1zEeLI80BttQqOaJJyHBsOGOuvRXY8c8dxINOxFuKYbf9jhP EjCKxzPRkWjXWjruArltN16oYzHMemcM2agGEg4LfQZtlWt4Jq+TEeVlFlZdJBGYgRtd aLGlHPINgwzso84nmkL9XgwcuMNZjsMftwwMFrzzxF8CuQ5PbJVkcjkU9EFt3MQL9+Q5 qUAEDmHAOh6pIglsVggtcSFVoPKYKtiOuH5HiD8pspPYOSJTNojCfh/weACdsFWNz/79 2CJRnq52jNNgoTK383dzKaV7VsW26JXbkO5Sx6gYWYxD+rSWEq6Y+WNPemWtfMC5BtkC lCLg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1692096224; x=1692701024; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=AYPNsi1tl/0GDFSQd4trv1IQAjRIoOCldAj6utrHW9I=; b=LvDUkcOUrOGAg3arQdhN+tSofYc3Vk94tldOle63n1CnFfwcmkkpxIEzLfUuJCA2H0 QkvbW7ZpCWEu8ul2TvlFK6OnulKBPZ7BbM6BNVgEZ6fVen5HCbuIpItVZ6WOeC5MzaT3 bRFnLonASf6D39LDkkhVr6OjrIF8+BkAK4h/Fd6Epb1S6JryA1YQTJub+tQ0fmYSAx9o UB3dvXWH9ROAbVybwWUXr24W3HjnuTe7phtWmPUpIGNI71dRvbaVNfy9Dp9cu43H6gew CKycPZSv4N7zKr/DvVoZnVVB0syacLKbXJrRxV6W4KGK4t2E+sX3bkUeays6vYd9vETz YM7w== X-Gm-Message-State: AOJu0YyXm6vAwV3amv1tpqtp7Y2zGUbWYZyya3FxBLy+BCVsayioWgM5 DAxgckVlWcsQT5ddwZyaB6s= X-Google-Smtp-Source: AGHT+IFT/ZySzwqKc9Vu47m3NtHFJhQcTa+4fAaJxkK4zkHQORY0GTYEDGrh/4x7l50Qp9yA/a1reg== X-Received: by 2002:a2e:b011:0:b0:2b5:7a87:a85a with SMTP id y17-20020a2eb011000000b002b57a87a85amr8385283ljk.13.1692096223533; Tue, 15 Aug 2023 03:43:43 -0700 (PDT) Received: from localhost.localdomain (pd9e9e2b1.dip0.t-ipconnect.de. [217.233.226.177]) by smtp.gmail.com with ESMTPSA id md15-20020a170906ae8f00b0098d486d2bdfsm6944627ejb.177.2023.08.15.03.43.42 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Tue, 15 Aug 2023 03:43:43 -0700 (PDT) From: Leif Middelschulte X-Google-Original-From: Leif Middelschulte To: Thierry Reding , =?utf-8?q?Uwe_Kleine-K=C3=B6n?= =?utf-8?q?ig?= , Shawn Guo , Sascha Hauer , Pengutronix Kernel Team , Fabio Estevam , NXP Linux Team Cc: Leif Middelschulte , linux-pwm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: [PATCH v3 2/4] pwm: imx27: avoid PWM consumer API Date: Tue, 15 Aug 2023 12:43:30 +0200 Message-Id: <20230815104332.55044-2-Leif.Middelschulte@gmail.com> X-Mailer: git-send-email 2.39.2 (Apple Git-143) In-Reply-To: <20230815104332.55044-1-Leif.Middelschulte@gmail.com> References: <20230310174517.rb7xxrougkse2lrc@pengutronix.de> <20230815104332.55044-1-Leif.Middelschulte@gmail.com> MIME-Version: 1.0 X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,FREEMAIL_FROM, RCVD_IN_DNSWL_BLOCKED,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-pwm@vger.kernel.org Access struct members directly as adviced[0]. [0] https://lore.kernel.org/lkml/20230310174517.rb7xxrougkse2lrc@pengutronix.de/T/#ec9560c1f613d9c0d7b77d72ad9051768812f80db Signed-off-by: Leif Middelschulte Reviewed-by: Uwe Kleine-König --- drivers/pwm/pwm-imx27.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/pwm/pwm-imx27.c b/drivers/pwm/pwm-imx27.c index 32389ca2da3e..c2a1e2030072 100644 --- a/drivers/pwm/pwm-imx27.c +++ b/drivers/pwm/pwm-imx27.c @@ -124,7 +124,7 @@ static int pwm_imx27_wait_fifo_empty(struct pwm_chip *chip, { struct pwm_imx27_chip *imx = to_pwm_imx27_chip(chip); struct device *dev = chip->dev; - unsigned int period_ms = DIV_ROUND_UP_ULL(pwm_get_period(pwm), NSEC_PER_MSEC); + unsigned int period_ms = DIV_ROUND_UP_ULL(pwm->state.period, NSEC_PER_MSEC); int tries = MX3_PWM_FIFOAV_EMPTY_LOOP; int fifoav; u32 sr; @@ -248,7 +248,7 @@ static void pwm_imx27_wait_fifo_slot(struct pwm_chip *chip, sr = readl(imx->mmio_base + MX3_PWMSR); fifoav = FIELD_GET(MX3_PWMSR_FIFOAV, sr); if (fifoav == MX3_PWMSR_FIFOAV_4WORDS) { - period_ms = DIV_ROUND_UP_ULL(pwm_get_period(pwm), + period_ms = DIV_ROUND_UP_ULL(pwm->state.period, NSEC_PER_MSEC); msleep(period_ms); From patchwork Tue Aug 15 10:43:31 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Leif Middelschulte X-Patchwork-Id: 1821327 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@legolas.ozlabs.org Authentication-Results: legolas.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org (client-ip=2620:137:e000::1:20; helo=out1.vger.email; envelope-from=linux-pwm-owner@vger.kernel.org; receiver=) Authentication-Results: legolas.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256 header.s=20221208 header.b=LUDpqjma; dkim-atps=neutral Received: from out1.vger.email (out1.vger.email [IPv6:2620:137:e000::1:20]) by legolas.ozlabs.org (Postfix) with ESMTP id 4RQ7FD3YMrz1ygB for ; Tue, 15 Aug 2023 20:44:48 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236508AbjHOKoN (ORCPT ); Tue, 15 Aug 2023 06:44:13 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59714 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236541AbjHOKnx (ORCPT ); Tue, 15 Aug 2023 06:43:53 -0400 Received: from mail-ej1-x62f.google.com (mail-ej1-x62f.google.com [IPv6:2a00:1450:4864:20::62f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 39F93199A; Tue, 15 Aug 2023 03:43:46 -0700 (PDT) Received: by mail-ej1-x62f.google.com with SMTP id a640c23a62f3a-986d8332f50so712457766b.0; Tue, 15 Aug 2023 03:43:46 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20221208; t=1692096225; x=1692701025; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=sduk85jgb4Rzoi+0BThhCqf7BU7Lkg9hkmERzbD9sNs=; b=LUDpqjmagiSq84kwsybeyWQZDC7l+URGFNMSBVRzkJYuR95dgNCI9rbrT7CAbtEhZk 03X4hMXJITjpUsBQNQ6WonRjOuglXzrBKso7gAhLdtwxQhUyG5jZJ9zOVHaBA5pyf1SZ EnLEKgsx5l7MWGkmoj6FCruDQU38cyVcxnvPgCa2QIyKz8nckkNVZ1xMifIYJbm3bi+E FSLCYs123CBBYQr+QOQvT5BTOCIf43+7MvcT44qgMxEQ4K67p/rjYim/iqp1ld9V4rR4 OfCm8VUSxLsfjMqCS5HcvhzXqtBHvj2MxcJQiynzGG95908KFZpfKp+LToZMmnrE5rLr Cj/g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1692096225; x=1692701025; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=sduk85jgb4Rzoi+0BThhCqf7BU7Lkg9hkmERzbD9sNs=; b=mIM46WTGTwaOZM0080cGxWnqVO94xM6G1WS0XGeaYKO7efwXT7wjhw+VNn7ZewnmS7 MiVYsVcxtL+MM7/oXUPu89Mxxp5FuiC0HGgf1MJvhPn2H0kFRccHvsv+ojN/OL6R5Ogf D0E5xLmuINyZmCIoDMgyg3cmTiN68hkyXKxWiRA34Z70AeVmwmo2fO8v3O/lwqzjDvRD Fuaykyooz/iDSNWT5Q9rukgx14W2oSRzcL1i2tB1TjVhmaxdkjqeHHsS8QNgREwAK/5t v57haUF+3sWNRQiD9DdEG0QM2sRL3esCWC+2lw900BreHNSxOsHz3Z1eA/8z0Ae14ZOm /07A== X-Gm-Message-State: AOJu0YweJZHhR64fUItYvLzn+xl4dpIBp4csaoHFI1QZ7vKeoLuHpeIm VlXZHsQSTjMyH6eofwA+0oA= X-Google-Smtp-Source: AGHT+IFHzcS38HnEee+VxY8yfIsaZCs/wKTJxbsgsL3GPtyM5JlHWnLE3Va5K1Voj/9n8TDkfi5wKw== X-Received: by 2002:a17:906:3196:b0:99c:6518:ce77 with SMTP id 22-20020a170906319600b0099c6518ce77mr8581512ejy.54.1692096224703; Tue, 15 Aug 2023 03:43:44 -0700 (PDT) Received: from localhost.localdomain (pd9e9e2b1.dip0.t-ipconnect.de. [217.233.226.177]) by smtp.gmail.com with ESMTPSA id md15-20020a170906ae8f00b0098d486d2bdfsm6944627ejb.177.2023.08.15.03.43.44 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Tue, 15 Aug 2023 03:43:44 -0700 (PDT) From: Leif Middelschulte X-Google-Original-From: Leif Middelschulte To: Thierry Reding , =?utf-8?q?Uwe_Kleine-K=C3=B6n?= =?utf-8?q?ig?= , Shawn Guo , Sascha Hauer , Pengutronix Kernel Team , Fabio Estevam , NXP Linux Team Cc: Leif Middelschulte , linux-pwm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: [PATCH v3 3/4] pwm: imx27: verify decreasing PWM FIFO av value Date: Tue, 15 Aug 2023 12:43:31 +0200 Message-Id: <20230815104332.55044-3-Leif.Middelschulte@gmail.com> X-Mailer: git-send-email 2.39.2 (Apple Git-143) In-Reply-To: <20230815104332.55044-1-Leif.Middelschulte@gmail.com> References: <20230310174517.rb7xxrougkse2lrc@pengutronix.de> <20230815104332.55044-1-Leif.Middelschulte@gmail.com> MIME-Version: 1.0 X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,FREEMAIL_FROM, RCVD_IN_DNSWL_BLOCKED,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-pwm@vger.kernel.org Avoid unnecessary sleeps as adviced[0], if the FIFO cannot be emptied. [0] https://lore.kernel.org/lkml/20230310174517.rb7xxrougkse2lrc@pengutronix.de/T/#ec9560c1f613d9c0d7b77d72ad9051768812f80db Signed-off-by: Leif Middelschulte --- drivers/pwm/pwm-imx27.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/drivers/pwm/pwm-imx27.c b/drivers/pwm/pwm-imx27.c index c2a1e2030072..9673e809d212 100644 --- a/drivers/pwm/pwm-imx27.c +++ b/drivers/pwm/pwm-imx27.c @@ -126,7 +126,7 @@ static int pwm_imx27_wait_fifo_empty(struct pwm_chip *chip, struct device *dev = chip->dev; unsigned int period_ms = DIV_ROUND_UP_ULL(pwm->state.period, NSEC_PER_MSEC); int tries = MX3_PWM_FIFOAV_EMPTY_LOOP; - int fifoav; + int fifoav, previous_fifoav = INT_MAX; u32 sr; while (tries--) { @@ -134,6 +134,10 @@ static int pwm_imx27_wait_fifo_empty(struct pwm_chip *chip, fifoav = FIELD_GET(MX3_PWMSR_FIFOAV, sr); if (fifoav == MX3_PWMSR_FIFOAV_EMPTY) return; + /* if the FIFO value does not decrease, there is another problem */ + if (previous_fifoav == fifoav) + break; + previous_fifoav = fifoav; msleep(period_ms); } dev_warn(dev, "FIFO has been refilled concurrently\n"); From patchwork Tue Aug 15 10:43:32 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Leif Middelschulte X-Patchwork-Id: 1821326 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@legolas.ozlabs.org Authentication-Results: legolas.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org (client-ip=2620:137:e000::1:20; helo=out1.vger.email; envelope-from=linux-pwm-owner@vger.kernel.org; receiver=) Authentication-Results: legolas.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256 header.s=20221208 header.b=CbvqMNyY; dkim-atps=neutral Received: from out1.vger.email (out1.vger.email [IPv6:2620:137:e000::1:20]) by legolas.ozlabs.org (Postfix) with ESMTP id 4RQ7FC6BpRz1yfS for ; Tue, 15 Aug 2023 20:44:47 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236495AbjHOKoL (ORCPT ); Tue, 15 Aug 2023 06:44:11 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59718 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236544AbjHOKnx (ORCPT ); Tue, 15 Aug 2023 06:43:53 -0400 Received: from mail-ej1-x62e.google.com (mail-ej1-x62e.google.com [IPv6:2a00:1450:4864:20::62e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AA0781BC5; Tue, 15 Aug 2023 03:43:47 -0700 (PDT) Received: by mail-ej1-x62e.google.com with SMTP id a640c23a62f3a-99bdeae1d0aso701752666b.1; Tue, 15 Aug 2023 03:43:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20221208; t=1692096226; x=1692701026; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=qq29fMSY5Klc/kVuoVBAvAdS2b2iC4pQqEMog/G6NPM=; b=CbvqMNyY7dJpa6T8z2Qqb+wixiM3zgNmkWHgfdD/0ZYQzoSaEqkaN6L6Yjl6KPujJE nE1c6Cz7BYRjLilWo0BJ7iS9ZbMJ/swLM8UCb6crmpq5KRlfSoh0oUgA89ElUMlFOlu9 qDud40u775qB39ZPJTa9EzIR8/AwKmM9Djzlaelh447owdP+in3ekyg0SKd1O/jx91Ts mnRod+8LV0Eyn7YGAs5B53yFtZwRC9zLXuuH2lMKaAQ413pixHu7aocPiWBtsFYEJRa6 DKu/YKUbefRUiEmscXIOOTnBQ5a/Vb/8yWXKvrcw5x54BkTb3tLoY93fpeLDTPdvGYgn AXOQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1692096226; x=1692701026; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=qq29fMSY5Klc/kVuoVBAvAdS2b2iC4pQqEMog/G6NPM=; b=b/jYPu8mO8oZ8hiwSaUkTBcCzaMXCTUb2Vik8zyfy3xuiGnGQgu9V40XdKn1iqyaF0 XRHVoOmGEf/sI1aQheC9sjpWbTtAP7SYb6qu3UUMaWFP35gDY7tJkj0Gu4Yne6Jesdm9 A3dE4I6bPVchaI5pcHlxAHRbPaoNXQX1Uu2o0l755E8S52bHy8jieuQumURuW+0MNtb0 lTJkaR17HLWo1dGkixmxSXoYJSKX0Cj2jQ58F1Sc+iROlKfEyDHRAiAH4J9im2u68Frd FG7hBy9dNhguiPX1i6Z2EUd5j+vvW518j9+sXj37teOCyxFUbvL0bNNZElwCpNmFFB9D Zttw== X-Gm-Message-State: AOJu0Ywiq37MgWew1f0cylyTuiaA17XLy+Q0oitrTPn/Pwf/h4ziPX5q Mcf5lkW7jazVq24zcmnJ+1tC8wrDRohMqK1k X-Google-Smtp-Source: AGHT+IH3sqmIl4zZ47TExcrKondXwj9ValS7C5VHObCT317j6Z8uHOOiDk6RxdjC0EmzA7xbcE7oIQ== X-Received: by 2002:a17:906:2ce:b0:993:f9b2:93c1 with SMTP id 14-20020a17090602ce00b00993f9b293c1mr10763562ejk.9.1692096225834; Tue, 15 Aug 2023 03:43:45 -0700 (PDT) Received: from localhost.localdomain (pd9e9e2b1.dip0.t-ipconnect.de. [217.233.226.177]) by smtp.gmail.com with ESMTPSA id md15-20020a170906ae8f00b0098d486d2bdfsm6944627ejb.177.2023.08.15.03.43.45 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Tue, 15 Aug 2023 03:43:45 -0700 (PDT) From: Leif Middelschulte X-Google-Original-From: Leif Middelschulte To: Thierry Reding , =?utf-8?q?Uwe_Kleine-K=C3=B6n?= =?utf-8?q?ig?= , Shawn Guo , Sascha Hauer , Pengutronix Kernel Team , Fabio Estevam , NXP Linux Team Cc: Leif Middelschulte , linux-pwm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: [PATCH v3 4/4] pwm: imx27: return error, if clean PWM setup fails Date: Tue, 15 Aug 2023 12:43:32 +0200 Message-Id: <20230815104332.55044-4-Leif.Middelschulte@gmail.com> X-Mailer: git-send-email 2.39.2 (Apple Git-143) In-Reply-To: <20230815104332.55044-1-Leif.Middelschulte@gmail.com> References: <20230310174517.rb7xxrougkse2lrc@pengutronix.de> <20230815104332.55044-1-Leif.Middelschulte@gmail.com> MIME-Version: 1.0 X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,FREEMAIL_FROM, RCVD_IN_DNSWL_BLOCKED,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-pwm@vger.kernel.org Instead of issuing a warning, return an error (as adviced[0]), if the FIFO cannot be cleanly set up. [0] https://lore.kernel.org/lkml/20230310174517.rb7xxrougkse2lrc@pengutronix.de/T/#ec9560c1f613d9c0d7b77d72ad9051768812f80db Signed-off-by: Leif Middelschulte --- drivers/pwm/pwm-imx27.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/drivers/pwm/pwm-imx27.c b/drivers/pwm/pwm-imx27.c index 9673e809d212..5fd6d34a7722 100644 --- a/drivers/pwm/pwm-imx27.c +++ b/drivers/pwm/pwm-imx27.c @@ -133,14 +133,15 @@ static int pwm_imx27_wait_fifo_empty(struct pwm_chip *chip, sr = readl(imx->mmio_base + MX3_PWMSR); fifoav = FIELD_GET(MX3_PWMSR_FIFOAV, sr); if (fifoav == MX3_PWMSR_FIFOAV_EMPTY) - return; + return 0; /* if the FIFO value does not decrease, there is another problem */ if (previous_fifoav == fifoav) break; previous_fifoav = fifoav; msleep(period_ms); } - dev_warn(dev, "FIFO has been refilled concurrently\n"); + + return -EAGAIN; } static int pwm_imx27_get_state(struct pwm_chip *chip, @@ -208,7 +209,9 @@ static int pwm_imx27_get_state(struct pwm_chip *chip, * been supplied and a period expired between the call of the wait * function and the subsequent readl. */ - pwm_imx27_wait_fifo_empty(chip, pwm); + ret = pwm_imx27_wait_fifo_empty(chip, pwm); + if (ret) + return ret; val = readl(imx->mmio_base + MX3_PWMSAR); } else { val = imx->duty_cycle;