From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1792651436; b=pLuP1cHlgh8LYe5zLZHHPR06kv3FunjMa20QSPTTKBzveOkiE3fpZeSIcdd592Z/I7Fk /URsqs3nHSnr0QW8C51cJMZiPIDzXDRjK9qgXMIIkQKxnY3KsIXtb5abt6W7C0CU7fLHP nHaTfrFTouP7G0TJXToi/UCYlUJDIEqepRoHjAlcmb8Z4egbZ/hIDZp2KfAcjc/MisnuD KcS3zzZUbdfzi9NEExt14gTQ2Yv3l8QeAN2k2zjLgnblOuokoOtm4auZoyucexK17SNbK yFNlRUfY3+VKv+2BpRzJvrFTBEd9XXbXnckMyl0RYdaaCNIbyGq4Q6fyUeu8Ir5Z27Q== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1792651436; h=Received:DKIM-Signature:Date:From:To:Cc:Subject:Message-ID: References:MIME-Version:Content-Type:Content-Disposition: Content-Transfer-Encoding:In-Reply-To; bh=aFucjpuwH0j10r8rB0xRq98gv+GUqPboTiWqHPsU1AY=; b=NnORHSoOHIQoo/jbA1GFigcHjgMoiMBpAnP3rnkFSEDgYgKBB1CxZRxJL2Y3xwqoiFjq vIhdMRvAxXOenr+tdBxN9RbRLOMfVJXDcUOpvS0pNQric77wswx1gNFElNpqajpusT8cZ mmsK3iTjUkfFhct+RSkeklvunn8YLRDfvgQEB3tNAYWuf6XDAiS8BMazSgYLWXq+f1gN0 Fi7OF5/5jzIpE+LCQrJ4tisqCr0+LJ8G8q/tm2eYd+rB2OrYESn78zdh6vXkoajJXI/jw 8bC/r1oR+UzgB13irsoyG2ei9qBD3cKB+VDXDHHpSLtopaeXaWzl5wHyC9tiRS9rURA== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=cePFW3Pc; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id CCBB2606A31B; Thu, 22 Oct 2026 06:43:55 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=cePFW3Pc Received: by smtp.kernel.org (Postfix) with ESMTPSA id 959781F000C1; Thu, 22 Oct 2026 06:43:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1792651435; bh=aFucjpuwH0j10r8rB0xRq98gv+GUqPboTiWqHPsU1AY=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=cePFW3Pc8RdsHIvENQO8gtCTXKpiGowW/j+CGwDXbGb/ag+JPQF5T4OgKFgQ9t1hP E5TZPEcE9TrkVjThtJ4uPlsL2X07kyz7LXakl5kd5wCwol2K6l5BsyApt4ZXv/a5Pe 5vzQl/ZYcmDUkZk1g2oYPQR33zF7oBMLsDAaN48bfdujQUjMdNV83CBRuQLKeCan9y MeNrm7Sv13nsv8SAOP2oBhxPZEZOawRSHAju8oFOU4KlPq4o0sp7jqxBZDFGrJYkpT EfVU6yHKMOnfZQkIGjnX5ZHBa3UDA63FdwG6zzv8viGOqxuutEuKWZu7JBrZZ/kclb OZWpQCnhjgfWA== Date: Thu, 22 Oct 2026 08:43:47 +0200 From: Lorenzo Pieralisi To: Robin Murphy Cc: Andy Shevchenko , "Rafael J. Wysocki (Intel)" , Mark Rutland , Marc Zyngier , Daniel Lezcano , Thomas Gleixner , Greg Kroah-Hartman , Danilo Krummrich , Hanjun Guo , Sudeep Holla , Wim Van Sebroeck , Guenter Roeck , Catalin Marinas , Will Deacon , Bartosz Golaszewski , linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, driver-core@lists.linux.dev, linux-watchdog@vger.kernel.org Subject: Re: [PATCH RFC 02/11] ACPI: Introduce irq_get() for static fwnodes Message-ID: References: <7f077fd3-9c67-409a-b46f-7f28a55c180b@arm.com> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <7f077fd3-9c67-409a-b46f-7f28a55c180b@arm.com> On Wed, Oct 21, 2026 at 12:18:39PM +0100, Robin Murphy wrote: > On 2026-10-21 10:06 am, Lorenzo Pieralisi wrote: > > On Wed, Oct 21, 2026 at 09:58:33AM +0300, Andy Shevchenko wrote: > > > On Tue, Oct 20, 2026 at 05:30:00PM +0200, Lorenzo Pieralisi wrote: > > > > On Mon, Oct 19, 2026 at 08:05:50PM +0200, Rafael J. Wysocki (Intel) wrote: > > > > > On Mon, Oct 19, 2026 at 12:34 PM Lorenzo Pieralisi > > > > > wrote: > > > > > > [...] > > > > > > > > Basically, yes, the idea is to defer the creation of the platform > > > > > device until the dependency is met. > > > > > > > > > > > till the dependencies are cleared but then, without a _CRS, where will > > > > > > the consumer driver find the platform device resources ? > > > > > > > > > > Well, good question. > > > > > > > > > > > There are multiple facets in this issue and possibly some of them have > > > > > > been already solved but I need to pull them together. > > > > > > > > > > > > > Note that the dependencies can be added to acpi_dep_list after > > > > > > > creating a struct acpi_device with acpi_add_single_object() and > > > > > > > acpi_scan_add_dep() is not really suitable for that, but it should be > > > > > > > doable if the dependencies can be found. > > > > > > > > > > > > > > > I need to have a deeper look into this next week but I wanted to ask first > > > > > > > > whether there was something I missed - most likely. > > > > > > > > > > > > > > Well, it is not really straightforward. > > > > > > > > > > > > Yes it is getting messy. This RFC, with all its flaws, does not transparently > > > > > > prevents enumeration but rather relies on -EPROBE_DEFER to sort out > > > > > > dependencies - though it does so by adding more stuff into ACPI static fwnode > > > > > > that to be honest I'd rather see gone. > > > > > > > > > > I think what you need is a notification mechanism that will trigger > > > > > when a specific device (enumerated via the ACPI Namespace) becomes > > > > > operational. It doesn't look like any of the existing ones (platform > > > > > device probe deferral or ACPI device dependencies tracking) is really > > > > > suitable for your use case. > > > > > > > > Yes. It might just be a notification from ACPI core to say "the driver for > > > > this ACPI device probed, go create platform devices that depends on it". > > > > > > > > We can check and track the dependency in code that does create those > > > > devices today. > > > > > > > > I will think about this to see how bad this might look like. > > > > > > Don't we do something similar in drivers/acpi/x86/lpss.c? > > > > I suppose I can add a notifier that checks whether the device whose > > companion represents the ACPI device a given platform device IRQ depends > > on was bound to its driver and then map the IRQ and add the platform device > > _then_ - after all that's what acpi_dev_clear_dependencies() does (similar > > at least). > > > > There is still the question - where the GSI number, flags should be > > stashed so that the notifier can grab them in a uniform way. We > > could simply attach platform data storing those values to a pdev, either on > > a per static table basis or generalize the data so that a single notifier > > would be able to deal with it. > > > > That or I can just piggyback on acpi_dev_clear_dependencies() and add > > a separate dep mechanism to acpi_dep_data that instead of being acpi_handle > > based the consumer is fwnode based (something Rafael mentioned before). > > > > I will have a stab at this and see what's the least bad solution I can > > come up with. > > > > I suppose we are scrapping the -EPROBE_DEFER solution (ie this set), > > what we are talking about above won't need to defer anything other > > than the time when platform devices are added. > > I dunno, that seems pretty drastic for some use-cases - the fact that a GSI > is described in a table doesn't necessarily mean it is critical to device > operation. If we don't even create the device until all possible resources > are available, then its driver never has any chance to decide whether it's > happy to ignore the deferral and just use MSIs or polling instead... I agree with you (but that's what we do for ACPI autodep and AFAICS OF devlinks - though there there might be opt-outs). To make -EPROBE_DEFER work I have to pursue the approach undertaken in this set and apply requested changes - I don't see any other way. Are we willing to accept the approach taken in this patchset (I can remove software nodes and make the whole thing ACPI static nodes self-contained) ? One way or another this ought to be sorted, please all let me know your take on this. Thanks, Lorenzo