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 1959EC433F5 for ; Thu, 5 May 2022 22:00:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1386142AbiEEWEY (ORCPT ); Thu, 5 May 2022 18:04:24 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53640 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230506AbiEEWEW (ORCPT ); Thu, 5 May 2022 18:04:22 -0400 Received: from mail-oi1-x22e.google.com (mail-oi1-x22e.google.com [IPv6:2607:f8b0:4864:20::22e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9D3BF2D1F2; Thu, 5 May 2022 15:00:39 -0700 (PDT) Received: by mail-oi1-x22e.google.com with SMTP id n24so5727431oie.12; Thu, 05 May 2022 15:00:39 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=cGqwZ+MurLuF+6+C7VAFY3bMj4Mfo5qjjgNeYm16yHQ=; b=ebi5F5iJN8bs6OKnKddbp99XnUnx5A9FzFpwOCk/4rAsfSkiJ/ggme+mOA0tTNr9Mu tnC0QeuXDnDfUPvLg/U0jgBQHL4CuPyTYUPtLvQEMjGJ0yb5yjB2hk5RVqBapyP0JH5t QUwQAn9ECic2SuF+mj6sImSRA9kvjL/NAXGiBJH/zeJPsZ+xRZ32Xqwzm7ARKgiwoyjW rN15AGha5WZVHmZ1Z8AAvUxd18Onx4fKmZ9GgR4XEZ3usaTdxcKhEkY4b6ouPe8XPGap 8Mqciy00omljTf03N0j0og8AvIF1jfxd9eghB3AuiQ1PcYHGctjoznKo1qW7z/WliS9J pufQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:sender:date:from:to:cc:subject:message-id :references:mime-version:content-disposition:in-reply-to; bh=cGqwZ+MurLuF+6+C7VAFY3bMj4Mfo5qjjgNeYm16yHQ=; b=uq0R91NXIEllfq87nT6dtT/Jo2X3OzWTdlkTBYL97xmE2RGBGeQXd2ttDcEyFU5uSI nrUc3HU4Ak2SyarKI/QzfclzSQTLcXUO6OUWhfyAwt8x+5/w4DlNR7xb/1fJCE6vOAx8 Lsswv5HqVaQlQbikj0F+TSxfsjdRMKM2x/UxnnCqKSw5eIYdL/Wvk7a7aozL5xhYe/6m zT0HZFFX+KlND++FPVM+udCCqniCd0f0Ay+sy9zFnHBNjFh3ov9Nw5+mv5KFb345i26W xQdcxXc8MylWjyyseLPqO4aOP2Cak58sHjaX1DgiRMVaAZOGRO+ba8bWpkimiMVtmYmQ UMXg== X-Gm-Message-State: AOAM531MBTRce7vGwETPjJ3ztbQ7XEMctJ6EEJee9QrVWsa4Z2qqAK08 PN7cT3kWE6u1rLS7EI0UAiA= X-Google-Smtp-Source: ABdhPJxOFHZG0E5qacFRJs5SRVLmlf/+hkbzPBD9+UOKEq7oa+Si+tMp9WB6xOwSfIMSDjDAMcSDhQ== X-Received: by 2002:a05:6808:2099:b0:326:6079:8229 with SMTP id s25-20020a056808209900b0032660798229mr146113oiw.197.1651788038916; Thu, 05 May 2022 15:00:38 -0700 (PDT) Received: from server.roeck-us.net ([2600:1700:e321:62f0:329c:23ff:fee3:9d7c]) by smtp.gmail.com with ESMTPSA id x47-20020a056830246f00b0060603221236sm1042734otr.6.2022.05.05.15.00.37 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 05 May 2022 15:00:38 -0700 (PDT) Sender: Guenter Roeck Date: Thu, 5 May 2022 15:00:37 -0700 From: Guenter Roeck To: Alexander Stein Cc: Bartlomiej Zolnierkiewicz , Jean Delvare , Thierry Reding , Uwe =?iso-8859-1?Q?Kleine-K=F6nig?= , Lee Jones , Markus Niebel , linux-hwmon@vger.kernel.org, linux-pwm@vger.kernel.org Subject: Re: [PATCH v2 1/1] hwmon: pwm-fan: dynamically switch regulator Message-ID: <20220505220037.GF1988936@roeck-us.net> References: <20220504124551.1083383-1-alexander.stein@ew.tq-group.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220504124551.1083383-1-alexander.stein@ew.tq-group.com> Precedence: bulk List-ID: X-Mailing-List: linux-hwmon@vger.kernel.org On Wed, May 04, 2022 at 02:45:51PM +0200, Alexander Stein wrote: > From: Markus Niebel > > A pwm value equal to zero is meant to switch off the pwm > hence also switching off the fan. Currently the optional > regulator is always on. When using this driver on boards > with an inverted pwm signal polarity this can cause running > the fan at maximum speed when setting pwm to zero. > The appropriate solution in this case would be to tell the software that the pwm is inverted. Turning off the regulator in that situation is a bad idea since setting the pwm value to 1 would set it to almost full speed. That does not really make sense. Guenter > The proposed changes switch the regulator off, when PWM is > currently enabled but pwm is requested to set to zero > and switch der regulator on, when PWM is currently disabled > but pwm shall be set to a no zero value. > > Add __set_pwm_and_regulator and rewrite __set_pwm to > handle regulator switching for the following conditions: > > - probe: pwm duty -> max, pwm state is unkwown: use __set_pwm > and enable regulator separately to keep the devm action > - off: new pwm duty is zero, pwm currently enabled: disable > regulator > - on: new pwm duty is non zero, pwm currently disabled: enable > regulator > > Signed-off-by: Markus Niebel > Signed-off-by: Alexander Stein > --- > Changes in v2: > * Added my own missing S-o-b > > drivers/hwmon/pwm-fan.c | 144 ++++++++++++++++++++++++++-------------- > 1 file changed, 93 insertions(+), 51 deletions(-) > > diff --git a/drivers/hwmon/pwm-fan.c b/drivers/hwmon/pwm-fan.c > index f12b9a28a232..b47d59fbe836 100644 > --- a/drivers/hwmon/pwm-fan.c > +++ b/drivers/hwmon/pwm-fan.c > @@ -97,18 +97,50 @@ static int __set_pwm(struct pwm_fan_ctx *ctx, unsigned long pwm) > unsigned long period; > int ret = 0; > struct pwm_state *state = &ctx->pwm_state; > + /* track changes of reg_en for error handling */ > + enum regulator_change { > + untouched, > + enabled, > + disabled, > + } reg_change = untouched; > > mutex_lock(&ctx->lock); > + > if (ctx->pwm_value == pwm) > goto exit_set_pwm_err; > > + if (ctx->reg_en) { > + if (pwm && !state->enabled) { > + reg_change = enabled; > + ret = regulator_enable(ctx->reg_en); > + } else if (!pwm && state->enabled) { > + reg_change = disabled; > + ret = regulator_disable(ctx->reg_en); > + } > + if (ret) > + goto exit_set_pwm_err; > + } > + > period = state->period; > state->duty_cycle = DIV_ROUND_UP(pwm * (period - 1), MAX_PWM); > state->enabled = pwm ? true : false; > > ret = pwm_apply_state(ctx->pwm, state); > - if (!ret) > + if (!ret) { > ctx->pwm_value = pwm; > + } else if (reg_change != untouched) { > + /* > + * revert regulator changes to keep consistency between > + * pwm and regulator > + */ > + int err; > + > + if (reg_change == enabled) > + err = regulator_disable(ctx->reg_en); > + else if (reg_change == disabled) > + err = regulator_enable(ctx->reg_en); > + } > + > exit_set_pwm_err: > mutex_unlock(&ctx->lock); > return ret; > @@ -280,18 +312,50 @@ static int pwm_fan_of_get_cooling_data(struct device *dev, > return 0; > } > > -static void pwm_fan_regulator_disable(void *data) > +/* > + * disable fan and regulator > + * if cleanup is true, disable pwm regardless of regulator disable result > + * this makes the function dual use for unloading driver and suspend > + */ > + > +static int __pwm_fan_disable_or_cleanup(struct pwm_fan_ctx *ctx, bool cleanup) > { > - regulator_disable(data); > + int ret; > + > + if (ctx->pwm_value) { > + /* keep ctx->pwm_state unmodified for pwm_fan_resume() */ > + struct pwm_state state = ctx->pwm_state; > + > + /* regulator is only enabled if pwm_value is not zero */ > + if (ctx->pwm_value && ctx->reg_en) { > + ret = regulator_disable(ctx->reg_en); > + if (ret) { > + pr_err("Failed to disable fan supply: %d\n", ret); > + if (!cleanup) > + return ret; > + } > + } > + > + state.duty_cycle = 0; > + state.enabled = false; > + ret = pwm_apply_state(ctx->pwm, &state); > + } > + > + return ret; > } > > -static void pwm_fan_pwm_disable(void *__ctx) > +static void pwm_fan_cleanup(void *__ctx) > { > struct pwm_fan_ctx *ctx = __ctx; > - > - ctx->pwm_state.enabled = false; > - pwm_apply_state(ctx->pwm, &ctx->pwm_state); > del_timer_sync(&ctx->rpm_timer); > + __pwm_fan_disable_or_cleanup(ctx, true); > +} > + > +static int pwm_fan_disable(void *__ctx) > +{ > + struct pwm_fan_ctx *ctx = __ctx; > + > + return __pwm_fan_disable_or_cleanup(ctx, false); > } > > static int pwm_fan_probe(struct platform_device *pdev) > @@ -324,19 +388,14 @@ static int pwm_fan_probe(struct platform_device *pdev) > return PTR_ERR(ctx->reg_en); > > ctx->reg_en = NULL; > - } else { > - ret = regulator_enable(ctx->reg_en); > - if (ret) { > - dev_err(dev, "Failed to enable fan supply: %d\n", ret); > - return ret; > - } > - ret = devm_add_action_or_reset(dev, pwm_fan_regulator_disable, > - ctx->reg_en); > - if (ret) > - return ret; > } > > pwm_init_state(ctx->pwm, &ctx->pwm_state); > + /* > + * Ensure the PWM is switched on (including the regulator), > + * independently from any previous PWM state > + */ > + ctx->pwm_state.enabled = false; > > /* > * __set_pwm assumes that MAX_PWM * (period - 1) fits into an unsigned > @@ -348,14 +407,17 @@ static int pwm_fan_probe(struct platform_device *pdev) > return -EINVAL; > } > > - /* Set duty cycle to maximum allowed and enable PWM output */ > + /* > + * Set duty cycle to maximum allowed and enable PWM output as well as > + * the regulator. In case of error nothing is changed > + */ > ret = __set_pwm(ctx, MAX_PWM); > if (ret) { > dev_err(dev, "Failed to configure PWM: %d\n", ret); > return ret; > } > timer_setup(&ctx->rpm_timer, sample_timer, 0); > - ret = devm_add_action_or_reset(dev, pwm_fan_pwm_disable, ctx); > + ret = devm_add_action_or_reset(dev, pwm_fan_cleanup, ctx); > if (ret) > return ret; > > @@ -461,42 +523,22 @@ static int pwm_fan_probe(struct platform_device *pdev) > return 0; > } > > -static int pwm_fan_disable(struct device *dev) > -{ > - struct pwm_fan_ctx *ctx = dev_get_drvdata(dev); > - int ret; > - > - if (ctx->pwm_value) { > - /* keep ctx->pwm_state unmodified for pwm_fan_resume() */ > - struct pwm_state state = ctx->pwm_state; > - > - state.duty_cycle = 0; > - state.enabled = false; > - ret = pwm_apply_state(ctx->pwm, &state); > - if (ret < 0) > - return ret; > - } > - > - if (ctx->reg_en) { > - ret = regulator_disable(ctx->reg_en); > - if (ret) { > - dev_err(dev, "Failed to disable fan supply: %d\n", ret); > - return ret; > - } > - } > - > - return 0; > -} > - > static void pwm_fan_shutdown(struct platform_device *pdev) > { > - pwm_fan_disable(&pdev->dev); > + struct pwm_fan_ctx *ctx = platform_get_drvdata(pdev); > + > + pwm_fan_cleanup(ctx); > } > > #ifdef CONFIG_PM_SLEEP > static int pwm_fan_suspend(struct device *dev) > { > - return pwm_fan_disable(dev); > + struct pwm_fan_ctx *ctx = dev_get_drvdata(dev); > + int ret; > + > + ret = pwm_fan_disable(ctx); > + > + return ret; > } > > static int pwm_fan_resume(struct device *dev) > @@ -504,6 +546,9 @@ static int pwm_fan_resume(struct device *dev) > struct pwm_fan_ctx *ctx = dev_get_drvdata(dev); > int ret; > > + if (ctx->pwm_value == 0) > + return 0; > + > if (ctx->reg_en) { > ret = regulator_enable(ctx->reg_en); > if (ret) { > @@ -512,9 +557,6 @@ static int pwm_fan_resume(struct device *dev) > } > } > > - if (ctx->pwm_value == 0) > - return 0; > - > return pwm_apply_state(ctx->pwm, &ctx->pwm_state); > } > #endif > -- > 2.25.1 >