From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-ed1-f47.google.com (mail-ed1-f47.google.com [209.85.208.47]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1889D28FAAC for ; Fri, 9 May 2025 11:51:41 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.208.47 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1746791504; cv=none; b=hJtx+Li0ReP6W2Pb7cbB6gqGKS0bP8gIadFN/8iO9Pd4Iv5ackjE1sJB3XtlPrxY/eOMH8tQdFIie6j6ZyF65n/hD8xsTVnSZNMnaxPHz0oi00GKh1VDyzJszyYR+RaoLknOAGWur4o+mscVofPmC9HfV7l38wcv+meWHGJ9zSo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1746791504; c=relaxed/simple; bh=94hSLVwahZL6uSGp/GCIw7ak3VmONi+Q3s+hjbITQj8=; h=Message-ID:Date:MIME-Version:Subject:From:To:Cc:References: In-Reply-To:Content-Type; b=cXtpqHWSdvPdjwoDT2Os113uhY15h2zllaOHvjaWSgj3qBtEmLHwJBM0c27lbFToIYT3UHtX7KZnyXRpVjM7G/Seizi0kMUVUNvHRJDeUM5tkZaDeHFwpNI/gQZol/eoquFWp6v89Vnj0cdGwFYZ85Ws47xSVfPGC2GeDKaG0Os= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=tuxon.dev; spf=pass smtp.mailfrom=tuxon.dev; dkim=pass (2048-bit key) header.d=tuxon.dev header.i=@tuxon.dev header.b=rRT6by3M; arc=none smtp.client-ip=209.85.208.47 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=tuxon.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=tuxon.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=tuxon.dev header.i=@tuxon.dev header.b="rRT6by3M" Received: by mail-ed1-f47.google.com with SMTP id 4fb4d7f45d1cf-5fab81d6677so3815028a12.1 for ; Fri, 09 May 2025 04:51:41 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=tuxon.dev; s=google; t=1746791500; x=1747396300; darn=vger.kernel.org; h=content-transfer-encoding:in-reply-to:content-language:references :cc:to:from:subject:user-agent:mime-version:date:message-id:from:to :cc:subject:date:message-id:reply-to; bh=HcCUAVth4/4X0ivCD1jla215xTKz2P8JDpUcQkYuzX4=; b=rRT6by3MuduwkSN/H4fHg3R3x+qWcNizG+URaLmW2ISNy7GYhh1fpzPFZ2G9ffPYyG izXnmui2iSTjI7TCX9BMj3pUeYywAHM/XTvh6qShsaZv7ZCfu5a9LmdeEdkWdQqHieBL 885NsSYTtAVhqY4H/WcTuZLEhEu2Hs8NH69GoHtqgg9WVluFkkvlEjNo8US434zLjjE3 9b9lUJByaoj/bm96D6m7jyu11BYEwGfxmkreqcvheUE1HT6/3KG89LlLTNICJ9ZSBMup vyXtV3ld8DkwKMs3j1IEaG9tbV8pTI6UDmLVZzJcr6fAofr+FdURv02Ky4LCzDjHihrF rgJw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1746791500; x=1747396300; h=content-transfer-encoding:in-reply-to:content-language:references :cc:to:from:subject:user-agent:mime-version:date:message-id :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=HcCUAVth4/4X0ivCD1jla215xTKz2P8JDpUcQkYuzX4=; b=GYZ/+4jLUGP1k8+6iICPtpLLjqq3i/sm5ytnoFywaicybzi/8Gm/mKA+5NzpRWTJoB F9FHx92tMGRcMRJaMdm/dIWgrANsr+4qJ6z8NKae80rzfXOmhc4e8DNKBHqzu+QHMYL3 Xkcin4QgF1gXdvGV+fYGDlomBa4PA9f+3j1QhetncjtmH+8z6t3EeHgWawNuZsoQ5pcR x7f6qzvE2CRstJM8qMANwkJE1TWuDSYgK0aNMmmaPOAShdadLsSB0qyMbFhynSdheO5n efIG6EhM7aTRHDPDRSKqMAZWQjti271vE7KV7mmhRZfebJ44EfpyaUiyqIL/xGBBE7Qw odWg== X-Forwarded-Encrypted: i=1; AJvYcCV/0iXa18ihqUfyS69wcHLK9ISiUWf7vpSeP0M4CQNls8eX/r6L0XO+UaHuVS1jkH6axFlmemoxFOk=@vger.kernel.org X-Gm-Message-State: AOJu0YwUeV2KKffDkmKhhj8+bV/hquKdtrgOXzNO4zRMOxR2tYId/Lg/ 2gqTjHk9PzLSD7fsNYR6IqlBbPBvVfN5U5jqK9gbuG0TSzU8TWxG9j+8WsHvRO0= X-Gm-Gg: ASbGncvVC9+hyB3CFcivSNatRo/DgCu7uSzSFTh5Ea514cBUOPxmOmPS6AkFdI++Bm/ hKc8rGcDecsF1vkuKylDPoIsF+rpkuAeuZ8pbYsEfSDYeEg4cRx3S9P3sYPr9+iB3fvvlaScLr6 Y3kONTlEPBCqba2CM/8Lu3mQ/4A8yMHMN2k8/MotblmMEdwtuFdvf3TR5B8yFUd6iG7uaDYEGpA iCtPvpFQQfDiNRKA8FkOeTg1tMLpzE0EvZMF2t4NmuNh8bMbUUtQeOSeta54AR4YrurT/kr0TQA XdWrGM0qflTs0rW7tPskoTajP9WpCG2JgmfcR/3yu/46LWH/ X-Google-Smtp-Source: AGHT+IFrGDRXG6FAVEd4uSESGaBsfaTJHvGQG8PV98kRwmaQFMuRJod0R5mnXx5DDPecf/kyISoRWw== X-Received: by 2002:a17:907:97d2:b0:ad1:77aa:503 with SMTP id a640c23a62f3a-ad219124207mr305429066b.36.1746791500229; Fri, 09 May 2025 04:51:40 -0700 (PDT) Received: from [192.168.50.4] ([82.78.167.50]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-ad2197bdd63sm138709266b.154.2025.05.09.04.51.38 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 09 May 2025 04:51:39 -0700 (PDT) Message-ID: <95f5923f-7a8f-4947-b588-419525930bcb@tuxon.dev> Date: Fri, 9 May 2025 14:51:38 +0300 Precedence: bulk X-Mailing-List: linux-iio@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] driver core: platform: Use devres group to free driver probe resources From: Claudiu Beznea To: Jonathan Cameron , "Rafael J. Wysocki" Cc: Daniel Lezcano , dakr@kernel.org, ulf.hansson@linaro.org, linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, linux-renesas-soc@vger.kernel.org, geert@linux-m68k.org, Claudiu Beznea , Greg Kroah-Hartman , linux-iio@vger.kernel.org, Dmitry Torokhov References: <20250215130849.227812-1-claudiu.beznea.uj@bp.renesas.com> <2025021539-untrained-prompter-a48f@gregkh> <4bf01946-90e3-4169-91fa-10d9f90310e9@tuxon.dev> <8d83ea72-bb81-4c63-bf69-28cf5848ae20@tuxon.dev> <20250305140309.744866b2@jic23-huawei> <20250330163129.02f24afb@jic23-huawei> <5bca6dfd-fe03-4c44-acf4-a51673124338@tuxon.dev> Content-Language: en-US In-Reply-To: <5bca6dfd-fe03-4c44-acf4-a51673124338@tuxon.dev> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Hi, Rafael, Ulf, PM list, On 09.04.2025 19:12, Claudiu Beznea wrote: > Hi, Rafael, > > On 30.03.2025 18:31, Jonathan Cameron wrote: >> On Thu, 27 Mar 2025 18:47:53 +0200 >> Claudiu Beznea wrote: >> >>> Hi, Rafael, >>> >>> On 06.03.2025 08:11, Dmitry Torokhov wrote: >>>> On Wed, Mar 05, 2025 at 02:03:09PM +0000, Jonathan Cameron wrote: >>>>> On Wed, 19 Feb 2025 14:45:07 +0200 >>>>> Claudiu Beznea wrote: >>>>> >>>>>> Hi, Daniel, Jonathan, >>>>>> >>>>>> On 15.02.2025 15:51, Claudiu Beznea wrote: >>>>>>> Hi, Greg, >>>>>>> >>>>>>> On 15.02.2025 15:25, Greg KH wrote: >>>>>>>> On Sat, Feb 15, 2025 at 03:08:49PM +0200, Claudiu wrote: >>>>>>>>> From: Claudiu Beznea >>>>>>>>> >>>>>>>>> On the Renesas RZ/G3S (and other Renesas SoCs, e.g., RZ/G2{L, LC, UL}), >>>>>>>>> clocks are managed through PM domains. These PM domains, registered on >>>>>>>>> behalf of the clock controller driver, are configured with >>>>>>>>> GENPD_FLAG_PM_CLK. In most of the Renesas drivers used by RZ SoCs, the >>>>>>>>> clocks are enabled/disabled using runtime PM APIs. The power domains may >>>>>>>>> also have power_on/power_off support implemented. After the device PM >>>>>>>>> domain is powered off any CPU accesses to these domains leads to system >>>>>>>>> aborts. >>>>>>>>> >>>>>>>>> During probe, devices are attached to the PM domain controlling their >>>>>>>>> clocks and power. Similarly, during removal, devices are detached from the >>>>>>>>> PM domain. >>>>>>>>> >>>>>>>>> The detachment call stack is as follows: >>>>>>>>> >>>>>>>>> device_driver_detach() -> >>>>>>>>> device_release_driver_internal() -> >>>>>>>>> __device_release_driver() -> >>>>>>>>> device_remove() -> >>>>>>>>> platform_remove() -> >>>>>>>>> dev_pm_domain_detach() >>>>>>>>> >>>>>>>>> During driver unbind, after the device is detached from its PM domain, >>>>>>>>> the device_unbind_cleanup() function is called, which subsequently invokes >>>>>>>>> devres_release_all(). This function handles devres resource cleanup. >>>>>>>>> >>>>>>>>> If runtime PM is enabled in driver probe via devm_pm_runtime_enable(), the >>>>>>>>> cleanup process triggers the action or reset function for disabling runtime >>>>>>>>> PM. This function is pm_runtime_disable_action(), which leads to the >>>>>>>>> following call stack of interest when called: >>>>>>>>> >>>>>>>>> pm_runtime_disable_action() -> >>>>>>>>> pm_runtime_dont_use_autosuspend() -> >>>>>>>>> __pm_runtime_use_autosuspend() -> >>>>>>>>> update_autosuspend() -> >>>>>>>>> rpm_idle() >>>>>>>>> >>>>>>>>> The rpm_idle() function attempts to resume the device at runtime. However, >>>>>>>>> at the point it is called, the device is no longer part of a PM domain >>>>>>>>> (which manages clocks and power states). If the driver implements its own >>>>>>>>> runtime PM APIs for specific functionalities - such as the rzg2l_adc >>>>>>>>> driver - while also relying on the power domain subsystem for power >>>>>>>>> management, rpm_idle() will invoke the driver's runtime PM API. However, >>>>>>>>> since the device is no longer part of a PM domain at this point, the PM >>>>>>>>> domain's runtime PM APIs will not be called. This leads to system aborts on >>>>>>>>> Renesas SoCs. >>>>>>>>> >>>>>>>>> Another identified case is when a subsystem performs various cleanups >>>>>>>>> using device_unbind_cleanup(), calling driver-specific APIs in the process. >>>>>>>>> A known example is the thermal subsystem, which may call driver-specific >>>>>>>>> APIs to disable the thermal device. The relevant call stack in this case >>>>>>>>> is: >>>>>>>>> >>>>>>>>> device_driver_detach() -> >>>>>>>>> device_release_driver_internal() -> >>>>>>>>> device_unbind_cleanup() -> >>>>>>>>> devres_release_all() -> >>>>>>>>> devm_thermal_of_zone_release() -> >>>>>>>>> thermal_zone_device_disable() -> >>>>>>>>> thermal_zone_device_set_mode() -> >>>>>>>>> struct thermal_zone_device_ops::change_mode() >>>>>>>>> >>>>>>>>> At the moment the driver-specific change_mode() API is called, the device >>>>>>>>> is no longer part of its PM domain. Accessing its registers without proper >>>>>>>>> power management leads to system aborts. >>>>>>>>> >>>>>>>>> Open a devres group before calling the driver probe, and close it >>>>>>>>> immediately after the driver remove function is called and before >>>>>>>>> dev_pm_domain_detach(). This ensures that driver-specific devm actions or >>>>>>>>> reset functions are executed immediately after the driver remove function >>>>>>>>> completes. Additionally, it prevents driver-specific runtime PM APIs from >>>>>>>>> being called when the device is no longer part of its power domain. >>>>>>>>> >>>>>>>>> Signed-off-by: Claudiu Beznea >>>>>>>>> --- >>>>>>>>> >>>>>>>>> Hi, >>>>> >>>>> Hi Claudiu, Greg, >>>>> >>>>> Sorry, I missed this thread whilst travelling and only saw it because >>>>> of reference from the in driver solution. >>>>> >>>>>>>>> >>>>>>>>> Although Ulf gave its green light for the approaches on both IIO [1], >>>>>>>>> [2] and thermal subsystems [3], Jonathan considered unacceptable the >>>>>>>>> approaches in [1], [2] as he considered it may lead to dificult to >>>>>>>>> maintain code and code opened to subtle bugs (due to the potential of >>>>>>>>> mixing devres and non-devres calls). He pointed out a similar approach >>>>>>>>> that was done for the I2C bus [4], [5]. >>>>>>>>> >>>>>>>>> As the discussions in [1], [2] stopped w/o a clear conclusion, this >>>>>>>>> patch tries to revive it by proposing a similar approach that was done >>>>>>>>> for the I2C bus. >>>>>>>>> >>>>>>>>> Please let me know you input. >>>>>>>> >>>>>>>> I'm with Jonathan here, the devres stuff is getting crazy here and you >>>>>>>> have drivers mixing them and side affects happening and lots of >>>>>>>> confusion. Your change here is only going to make it even more >>>>>>>> confusing, and shouldn't actually solve it for other busses (i.e. what >>>>>>>> about iio devices NOT on the platform bus?) >>>>> >>>>> In some cases they are already carrying the support as per the link >>>>> above covering all i2c drivers. I'd like to see a generic solution and >>>>> I suspect pushing it to the device drivers rather than the bus code >>>>> will explode badly and leave us with subtle bugs where people don't >>>>> realise it is necessary. >>>>> >>>>> https://lore.kernel.org/all/20250224120608.1769039-1-claudiu.beznea.uj@bp.renesas.com/ >>>>> is a lot nastier looking than what we have here. I'll review that in a minute >>>>> to show that it need not be that bad, but none the less not pleasant. >>>>> >>>>> +CC linux-iio to join up threads and Dmitry wrt to i2c case (and HID that does >>>>> similar) >>>> >>>> We should not expect individual drivers handle this, because this is a >>>> layering violation: they need to know implementation details of the bus >>>> code to know if the bus is using non-devres managed resources, and >>>> adjust their behavior. Moving this into driver core is also not >>>> feasible, as not all buses need it. So IMO this should belong to >>>> individual bus code. >>>> >>>> Instead of using devres group a bus may opt to use >>>> devm_add_action_or_reset() and other devm APIs to make sure bus' >>>> resource unwinding is carried in the correct order relative to freeing >>>> driver-owned resources. >>> >>> Can you please let us know your input on the approach proposed in this >>> patch? Or if you would prefer devm_add_action_or_reset() as suggested by >>> Dmitry? Or if you consider another approach would fit better? >>> >>> Currently there were issues identified with the rzg2l-adc driver (driver >>> based solution proposed in [1]) and with the rzg3s thermal driver (solved >>> by function rzg3s_thermal_probe() from [2]). >>> >>> As expressed previously by Jonathan and Dimitry this is a common problem >>> and as the issue is due to a call in the bus driver, would be better and >>> simpler to handle it in the bus driver. Otherwise, individual drivers would >>> have to be adjusted in a similar way. >>> >> >> Rafael, >> >> Greg suggested we ask for your input on the right option: >> >> https://lore.kernel.org/all/2025032703-genre-excitable-9473@gregkh/ >> (that thread has the other option). > > Can you please let us know your opinion on this? Can you please let us know if you have any suggestions for this? Thank you, Claudiu