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=-2.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 5F1D8C433DF for ; Thu, 9 Jul 2020 13:48:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 386FD2073A for ; Thu, 9 Jul 2020 13:48:20 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="eELWqoGs" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726340AbgGINsT (ORCPT ); Thu, 9 Jul 2020 09:48:19 -0400 Received: from us-smtp-1.mimecast.com ([205.139.110.61]:39898 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727103AbgGINsT (ORCPT ); Thu, 9 Jul 2020 09:48:19 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1594302497; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=oZs9AErY+eQgpCGxcTsul8XzFzR2Qfr+Xb/wqEYukpw=; b=eELWqoGsdfhV4D36rD6Uao4WoImME9c/AXHlJL78GaUvgDOV9CIcS5WBzCKiw10TI6BGMF JhMmXNAiCd3Ygsr9h08gGFDuSTQo3z4FxLpTsW/hmy837qs32DY6tzSRgoxuwQPfDZI0ip yvlAoKxfeI75Z7FBjYYXGS5TTCWajJg= Received: from mail-wm1-f72.google.com (mail-wm1-f72.google.com [209.85.128.72]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-348-0Tt-B6QhOEmTdbm1JkfE8g-1; Thu, 09 Jul 2020 09:48:16 -0400 X-MC-Unique: 0Tt-B6QhOEmTdbm1JkfE8g-1 Received: by mail-wm1-f72.google.com with SMTP id v11so2223627wmb.1 for ; Thu, 09 Jul 2020 06:48:16 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=oZs9AErY+eQgpCGxcTsul8XzFzR2Qfr+Xb/wqEYukpw=; b=bX6v0ThMC6WUQR4nlhN2E5VKOIjKA99Nko8Z9ZIIa8VjHwy3N6kpGzMQDfBZWSBn2s MS+5Ti0zBCr/9eUf1C2xkBaZpiNsMVVntMBqnxIDCFCj2mgG4RiOCow4gXrJFSypOWE7 e+941gLjbp1fAv2bDrZTcOLd2HLTBW3HiCrjBDdy5R8VVvktfjSVquFXRlUxEn+MD5SS S95qYjMfXGtf/YAGqrFPUrh/C4pigUdhFu02wBl9/RLKVSJDEX7G54y/RZczetuIk8m0 6ipntPvxiAsxjm1pXpREEyUhYXqBJAV3sLnjElNY3c4CDWWFmo2ORRCPnALOoXKvhr0h N2Pw== X-Gm-Message-State: AOAM532ZYKPT8wBcEgSvZ1YkX27N8lD/PX/uvyZOTBVy2zUsL16LvwEE fyT/ogbm62HeRqhpWSYgIVRMLOUypFua7t3sHhMho1gMQUV4U5Ih7gv6b6NV1pSzTQ1Wz1gF1C3 tfg6zq5iEJiLIUPKri8zgOA== X-Received: by 2002:a1c:449:: with SMTP id 70mr44235wme.149.1594302494647; Thu, 09 Jul 2020 06:48:14 -0700 (PDT) X-Google-Smtp-Source: ABdhPJxuuC+JM9A1gKl2XR85+WZwwYVCoVivUZyp1H46ayENTaqORebNvPr++i1WNeaEEEcapYMsTg== X-Received: by 2002:a1c:449:: with SMTP id 70mr44190wme.149.1594302494345; Thu, 09 Jul 2020 06:48:14 -0700 (PDT) Received: from x1.localdomain ([2a0e:5700:4:11:334c:7e36:8d57:40cb]) by smtp.gmail.com with ESMTPSA id v12sm5532702wrt.31.2020.07.09.06.48.13 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 09 Jul 2020 06:48:13 -0700 (PDT) Subject: Re: [PATCH v4 05/16] pwm: lpss: Use pwm_lpss_apply() when restoring state on resume To: Andy Shevchenko Cc: Thierry Reding , =?UTF-8?Q?Uwe_Kleine-K=c3=b6nig?= , Jani Nikula , Joonas Lahtinen , Rodrigo Vivi , =?UTF-8?B?VmlsbGUgU3lyasOkbMOk?= , "Rafael J . Wysocki" , Len Brown , linux-pwm@vger.kernel.org, intel-gfx , dri-devel@lists.freedesktop.org, Mika Westerberg , linux-acpi@vger.kernel.org References: <20200708211432.28612-1-hdegoede@redhat.com> <20200708211432.28612-6-hdegoede@redhat.com> <20200709133609.GY3703480@smile.fi.intel.com> From: Hans de Goede Message-ID: Date: Thu, 9 Jul 2020 15:48:12 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.9.0 MIME-Version: 1.0 In-Reply-To: <20200709133609.GY3703480@smile.fi.intel.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-acpi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-acpi@vger.kernel.org Hi, On 7/9/20 3:36 PM, Andy Shevchenko wrote: > On Wed, Jul 08, 2020 at 11:14:21PM +0200, Hans de Goede wrote: >> Before this commit a suspend + resume of the LPSS PWM controller >> would result in the controller being reset to its defaults of >> output-freq = clock/256, duty-cycle=100%, until someone changes >> to the output-freq and/or duty-cycle are made. >> >> This problem has been masked so far because the main consumer >> (the i915 driver) was always making duty-cycle changes on resume. >> With the conversion of the i915 driver to the atomic PWM API the >> driver now only disables/enables the PWM on suspend/resume leaving >> the output-freq and duty as is, triggering this problem. >> >> The LPSS PWM controller has a mechanism where the ctrl register value >> and the actual base-unit and on-time-div values used are latched. When >> software sets the SW_UPDATE bit then at the end of the current PWM cycle, >> the new values from the ctrl-register will be latched into the actual >> registers, and the SW_UPDATE bit will be cleared. >> >> The problem is that before this commit our suspend/resume handling >> consisted of simply saving the PWM ctrl register on suspend and >> restoring it on resume, without setting the PWM_SW_UPDATE bit. >> When the controller has lost its state over a suspend/resume and thus >> has been reset to the defaults, just restoring the register is not >> enough. We must also set the SW_UPDATE bit to tell the controller to >> latch the restored values into the actual registers. >> >> Fixing this problem is not as simple as just or-ing in the value which >> is being restored with SW_UPDATE. If the PWM was enabled before we must >> write the new settings + PWM_SW_UPDATE before setting PWM_ENABLE. >> We must also wait for PWM_SW_UPDATE to become 0 again and depending on the >> model we must do this either before or after the setting of PWM_ENABLE. >> >> All the necessary logic for doing this is already present inside >> pwm_lpss_apply(), so instead of duplicating this inside the resume >> handler, this commit makes the resume handler use pwm_lpss_apply() to >> restore the settings when necessary. This fixes the output-freq and >> duty-cycle being reset to their defaults on resume. > > ... > >> +static int __pwm_lpss_apply(struct pwm_chip *chip, struct pwm_device *pwm, >> + const struct pwm_state *state, bool from_resume) >> { >> struct pwm_lpss_chip *lpwm = to_lpwm(chip); >> int ret; >> >> if (state->enabled) { >> if (!pwm_is_enabled(pwm)) { >> - pm_runtime_get_sync(chip->dev); >> + if (!from_resume) >> + pm_runtime_get_sync(chip->dev); >> + >> ret = pwm_lpss_is_updating(pwm); >> if (ret) { >> - pm_runtime_put(chip->dev); >> + if (!from_resume) >> + pm_runtime_put(chip->dev); >> + >> return ret; >> } >> pwm_lpss_prepare(lpwm, pwm, state->duty_cycle, state->period); >> pwm_lpss_cond_enable(pwm, lpwm->info->bypass == false); >> ret = pwm_lpss_wait_for_update(pwm); >> if (ret) { >> - pm_runtime_put(chip->dev); >> + if (!from_resume) >> + pm_runtime_put(chip->dev); >> + >> return ret; >> } >> pwm_lpss_cond_enable(pwm, lpwm->info->bypass == true); > >> } >> } else if (pwm_is_enabled(pwm)) { >> pwm_lpss_write(pwm, pwm_lpss_read(pwm) & ~PWM_ENABLE); >> - pm_runtime_put(chip->dev); >> + >> + if (!from_resume) >> + pm_runtime_put(chip->dev); >> } > > I'm wondering if splitting more will make this look better, like: > > ... > if (from_resume) { > ret = pwm_lpss_prepare_enable(...); // whatever name you think suits better > } else { > pm_runtime_get_sync(...); > ret = pwm_lpss_prepare_enable(...); > if (ret) > pm_runtime_put(...); > } > ... > That is a good idea, I like it. We already had multiple pm_runtime_put() calls before for the error handlig and this patch did not make it any better. So adding a pwm_lpss_prepare_enable() helper (the name works for) will also cleanup the original code. I will add this helper as a separate preparation patch for this one in v5 of the patch-set. Regards, Hans