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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 56359E7FDC7 for ; Mon, 2 Feb 2026 20:14:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To: Content-Transfer-Encoding:Content-Type:MIME-Version:References:Message-ID: Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=sbVzDr6j8Cnfut/dHFXPjRRVJpGHldRxEVpuedl20WE=; b=JICLLsXEgnrojfMS/8n5o3oy7f Koksk9TqnswmU0b88eHdaqPIzWptDpC5FHN9vizbV+hmvhkyxta7iQ8zzBnz3RmpW1BvlIw3BgNMg qEbRoMMndVkMJ6vwNoWfrGvEXtfjaHY2oKLi5t5d1aOebyjgMqn4Z7xXXIwLCHzDvzH66cLlJ8PK1 I/TOai/vNp7enUka1Eqm+gSF26Ji4uEUS0KD/n2ezOqoib4tvPHyzGNQEcbFmW/KA6NkGKy5s2i7O VSS8dmnr7IxedsiMmu/YNdt9Dvebbetu03aa0TAkAoqaSKzjpeHZ+MdnAO7BCIoG8oKZ68M8aSmpw zQKB9ReQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1vn0Jg-00000005adL-04HK; Mon, 02 Feb 2026 20:14:36 +0000 Received: from mail-pl1-x633.google.com ([2607:f8b0:4864:20::633]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1vn0Je-00000005acv-0w32 for linux-arm-kernel@lists.infradead.org; Mon, 02 Feb 2026 20:14:35 +0000 Received: by mail-pl1-x633.google.com with SMTP id d9443c01a7336-2a76b39587aso195ad.0 for ; Mon, 02 Feb 2026 12:14:33 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1770063272; x=1770668072; darn=lists.infradead.org; h=in-reply-to:content-transfer-encoding:content-disposition :mime-version:references:message-id:subject:cc:to:from:date:from:to :cc:subject:date:message-id:reply-to; bh=sbVzDr6j8Cnfut/dHFXPjRRVJpGHldRxEVpuedl20WE=; b=zqAggLfcy1dYmkTNt/th5OFfhejvZQRxmwhu1QYsBqlP8T1JI6R4zs/gl/KdAd+YSO rmc59cz0ryKIB4+wjltlG58+qw+bZTvEOftadrePgZmJnpJvZtCk4mmOmsWWniqgqTKp UwzmdETKQFOWU87M9pCHMH1WOlChVID7x24th7E0eWlYSWeI3j6yEGw/izzUBQj9AJFS dEd4/CSD0XG89OR7/mfiuJTz94s3DuRBQJEc0hARd6Bc6rNcuHaFJK8Xw4wmpQC1cTVj oQ1uzoH1L8JT70zsgK1urdfMhdUF29guRNqw53fPS9azUQlbqfet0hfBNvAaHrKFLoVC 2P2Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1770063272; x=1770668072; h=in-reply-to:content-transfer-encoding:content-disposition :mime-version:references:message-id:subject:cc:to:from:date:x-gm-gg :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=sbVzDr6j8Cnfut/dHFXPjRRVJpGHldRxEVpuedl20WE=; b=HfMXR9bq+XEMARqdCbheIZPZdLGw99p20uBVlsgSaEV9Dga3lmMoFrm2zNO6/HNquF Cf3vlYc2JfOmIAXsmiYQ1bOtVZPOw2iYJhUDC4a6ooOjsNUSbu7oixI48ru3qXiEqUh2 SthPhV+bdAY1LxG01wHzLbDsQRJtnv2lS838uIdKdygf5uEc0GpyI7j2BOZTOAukJign 0h3ZN+0LJqHmyVAGKYiITf2fZvyrtowZzdi/6vIZbxzizFlzBn/Wo8511M2lzGpldYPI JyB0rCqHc4LzIPd4ikNQHJA9mNYat6vP1VhN0AMQBlOw5xObNtDDI1HIuHOolJ8cm3Mu ZMxg== X-Forwarded-Encrypted: i=1; AJvYcCWYFCvYHvNKPoQoiZOlAnU1pU2oFgjAZDl1TbGFsLZngYIAk0xxFeiOxd6SjBzdoghF14NxJWoYFIgOTGoqpQqH@lists.infradead.org X-Gm-Message-State: AOJu0YzyJW85pqHOTqtlqk2DELnP6A7sV42IYiF31BIGLqzwGeFus4rS bp3cC1X5xTlZVIpz2oGXO74BClOuVwm/ryejQnDB8cqzEZk0qA3mC2CJtBcCu4d4/A== X-Gm-Gg: AZuq6aJYSuhhOQ5NViGEcGCBpn//ctCpLUWWdRFKHZW+EtTb/oDhRNpExc/9REVxsBe Pb4rBL+U/U5N2+qHY3TdX97307KnVDuR90HmIDd5Vtujn4DXQxFaenIQE8Iqv7+rYOudUMQj7bu wnhPchobRCmRoOBc4+o3LyuLrR7LaDup1nam/fXqdbgKK+7ihldQZdZlf+HuTRUwlUKrGD1dLmJ HCQkEEhtkz6Phw5Jzbhsvv+srIqxfeT0a9Ubp5qOXcYq7fuLk37pBn9dDDcqqnxFzz8kQ23+1iV sk+7yrewpmCIikb02oRNI8AcXnV0YjwKX41hipKpiDsnyvH9vOBMe6oUWK3rlY+31s4P6DEKYlh RN3IR1pfr69HEjSYJrjmarwqQPCquP8infEKgznoSmKoxbGrgAIWHVO1VyCbazBrPxjoiN7pLsD cJVHUsTaGBsLGPR5c7qlLlFnNl/QXBrTHY6uBvL39R0BJ5NTXE X-Received: by 2002:a17:903:1a24:b0:29e:27f4:bac0 with SMTP id d9443c01a7336-2a92546efd1mr619255ad.16.1770063272159; Mon, 02 Feb 2026 12:14:32 -0800 (PST) Received: from google.com (222.245.187.35.bc.googleusercontent.com. [35.187.245.222]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2a88b4c3d2bsm161078895ad.53.2026.02.02.12.14.28 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 02 Feb 2026 12:14:31 -0800 (PST) Date: Mon, 2 Feb 2026 20:14:26 +0000 From: Pranjal Shrivastava To: Robin Murphy Cc: Prakash Gupta , Will Deacon , Joerg Roedel , Rob Clark , Connor Abbott , linux-arm-msm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, iommu@lists.linux.dev, linux-kernel@vger.kernel.org, Akhil P Oommen , Pratyush Brahma Subject: Re: [PATCH] iommu/arm-smmu: Use pm_runtime in fault handlers Message-ID: References: <20260127-smmu-rpm-v1-1-2ef2f4c85305@oss.qualcomm.com> <9fb8f661-a235-4f86-bc10-f80a21a8fa9d@arm.com> <00fcbcf2-3f48-410d-88a3-88dc834c1ed7@oss.qualcomm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260202_121434_262001_B9F83522 X-CRM114-Status: GOOD ( 13.14 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Wed, Jan 28, 2026 at 06:44:35PM +0000, Robin Murphy wrote: > [ +Pranjal as this might matter for v3 too... ] > Hi Robin, To weigh in from the arm-smmu-v3 side, we’ve attempted to address the "can of worms" regarding power races by leaning on these differences: - Threaded IRQs for PRI/Events: In the recent series[1], the PRI and event handlers are fully threaded. This allows us to call arm_smmu_rpm_get() safely, as the handler can sleep while waiting for the hardware to resume. - GERROR Handling: Since GERROR remains a hard IRQ, we handle any pending gerrors in the suspend callback before the SMMU actually powers down. Any GERROR interrupts received while the device was suspended are treated as spurious and ignored. Thanks, Praan [1] https://lore.kernel.org/all/20260126151157.3418145-1-praan@google.com/ [...] > > Hmm, but then how *do* we actually guarantee that autosuspend doesn't happen > to kick in and power down the SMMU just as a hardirq handler runs, when > there's some unexpected event? I fear there's a horrible can of worms > here... > > Thanks, > Robin.