From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=192.198.163.15 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1792562280; b=adE4BAo918EUAUYnR7D7E2XNgzj2WjvIYd81Jkvj/JL63/9dsjcIue5Zv0l+YL2/4pvu QVjVl9wdTwzbP31/ZznXmWKEm2tvJ3HKWRr95MSxKf9c862SiP/Q89pkXFjVun4UUQT7r 7sLS4euyVTSbFYg1gvlGIe+0NsSTeMIw7AnkNqmCjDH17F+x8BsYe519kfSwKvzBDx6/z wt9vP9PNN3RYL3tqN7juoULBCafJ1IqYZ4OeW2xSOUi62mjDZjR2abDX7TFpl3RMyouxF xIQX+ujAMPsvllSHhngCi6Ys/YJ/0gEPtSy9pwLL2Ktm6Kxab7lks5pBNplumNwrrUQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1792562280; h=DMARC-Filter:DKIM-Signature:X-CSE-ConnectionGUID:X-CSE-MsgGUID: X-IronPort-AV:X-IronPort-AV:Received:X-CSE-ConnectionGUID: X-CSE-MsgGUID:X-ExtLoop1:X-IronPort-AV:Received:Message-ID:Date: MIME-Version:User-Agent:Subject:To:Cc:References:Content-Language: From:In-Reply-To:Content-Type:Content-Transfer-Encoding; bh=G8dYOpxn7MC+ZuaGnfx+ivHYE4BwvuIFkRKXEM8ocss=; b=XcD+LmheIuwTAot7uoIuLb8mkqvxNnHqkyPUo8nooiFrlbpj0qM3WRV03A4QzdNkWLs/ 77qs8Mvg3B8TrEnyCpHx8lhcG4NW0zpibvW6rWQsHBf7ujy15QST/S5AttyDOii2H9mzm P49JJfZLd6YbyuoYJahBctTjmtqQYUM6vPsGgS58yvOwtdjsbqin910FKSjKJL0VPKOID lfeO0qQOLKgJDkJXvgqxJKwcT/Xg7FRjIVeaWuQeZu9HDPtlusBskPEO0wCXJGkVUDZtu x0a6opk8riROHznAS0fXHiFgea3orSQ3X1+Pj6WeqURtGEzGImROf1r6I/ByK9RJmhQ== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=linux.intel.com; spf=pass smtp.mailfrom=linux.intel.com; dkim=pass header.d=intel.com header.i=@intel.com header.a=rsa-sha256 header.s=Intel header.b=T5Wk1+WC; arc=none smtp.remote-ip=192.198.163.15 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.15]) (using TLSv1.2 with cipher ECDHE-ECDSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3BEC3606A31A; Wed, 21 Oct 2026 05:57:58 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 3BEC3606A31A Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=intel.com header.i=@intel.com header.a=rsa-sha256 header.s=Intel header.b=T5Wk1+WC DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1792562280; x=1824098280; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=H7Us3csM7KlqfmOQtYVzQN6z5KTrQAj7QwzbfGFGHNY=; b=T5Wk1+WCQT5QqdOIvHlcfbIuesT/Svk1Ecw+Cg+HYdAIs+PiumPSeaPJ RacyYYf6MEh2XfvlmenBSgn0nd4+liEQ2nkC+RIZlHgyrr5nTLyLpgTZG DV/SUwsUh97rqBsjwLCG1s9wf/h1VOltJBvwhQiTLFYi6nOlCcJQikycd vb1452D/xw2+EpgOKZr+lGfF2JaSFTv3jg7VRTryS9S4PxReQeU/ewbNd pIwqqizSSHZHrvWitlMPeF8CIwad0bwXO8dXLqrspfO3tp8VjVva2f0WI Syh8TPCsra9OUjWnMaJpoSGffXZCNLYMYEQS2N2bktgJfP1AQBB41IWdG g==; X-CSE-ConnectionGUID: P9aYScA2TGK0udrcXyEGFw== X-CSE-MsgGUID: K0tFR3+jRha0AC/BJzeHCw== X-IronPort-AV: E=McAfee;i="6800,10657,11941"; a="1290586" X-IronPort-AV: E=Sophos;i="6.27,169,1787036400"; d="scan'208";a="1290586" Received: from fmviesa005.fm.intel.com ([10.60.135.145]) by fmvoesa109.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 20 Oct 2026 22:57:59 -0700 X-CSE-ConnectionGUID: doxQZF4GRc2o6suR8aK/ng== X-CSE-MsgGUID: Off98YcyQr2i3X7DBKcVGg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.27,169,1787036400"; d="scan'208";a="3067035" Received: from blu2-desk.sh.intel.com (HELO [10.239.156.26]) ([10.239.156.26]) by smtpauth.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 20 Oct 2026 22:57:56 -0700 Message-ID: <50cac102-9b50-4d0d-af58-8aac51a6d51c@linux.intel.com> Date: Wed, 21 Oct 2026 13:57:53 +0800 X-Mailing-List: iommu@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [REGRESSION] BCM4355 Wi-Fi fails with Intel IOMMU on 7.3.0-2-t2-noble To: Peter Kiddier , linux-wireless@vger.kernel.org Cc: brcm80211@lists.linux.dev, iommu@lists.linux.dev, arend.vanspriel@broadcom.com, regressions@lists.linux.dev References: Content-Language: en-US From: Baolu Lu In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 10/20/26 19:32, Peter Kiddier wrote: > Hello, > > I am reporting a Wi-Fi regression on a 2018 Apple MacBook Air with a > T2 chip, running Linux Mint Zena based on Ubuntu 24.04. > > The Broadcom BCM4355 Wi-Fi device works with kernel 7.2.11-3-t2-noble > but fails with 7.3.0-2-t2-noble. Disabling the Intel IOMMU using > intel_iommu=off restores Wi-Fi on 7.3.0-2. > > Hardware: > - Apple MacBook Air 2018 (MacBookAir8,1) > - Wi-Fi: Broadcom BCM4355 802.11ac Wireless LAN SoC > - PCI ID: 14e4:43dc (subsystem 106b:0843) > - Driver: brcmfmac > - Interface: wlp2s0 > > Test results: > > - 7.2.11-3-t2-noble, default kernel command line: Wi-Fi works. > - 7.3.0-2-t2-noble, default kernel command line: Wi-Fi fails. > - 7.3.0-2-t2-noble with intel_iommu=off: Wi-Fi works. > - Reloading brcmfmac on the failing configuration does not restore Wi-Fi. > > On the failing 7.3.0-2 boot, the driver detects the device, loads its > firmware and creates wlp2s0: > > brcmfmac 0000:02:00.0: enabling device (0000 -> 0002) > brcmfmac: brcmf_fw_alloc_request: using brcm/brcmfmac4355c1-pcie for > chip BCM4355/12 > brcmfmac: brcmf_c_process_txcap_blob: TxCap blob found, loading > brcmfmac: brcmf_c_preinit_dcmds: Firmware: BCM4355/12 wl0: Jul 8 2023 > 17:49:51 version 9.30.503.0.32.5.87 FWID 01-e74b9cb0 > brcmfmac 0000:02:00.0 wlp2s0: renamed from wlan0 > > However, Wi-Fi subsequently stops responding. The kernel log reports > errors including: > > brcmf_msgbuf_query_dcmd: Timeout on response for query command > brcmf_cfg80211_scan: scan error (-5) > brcmf_run_escan: error (-5) > brcmf_msgbuf_tx_ioctl: Failed to reserve space in commonring > brcmf_cfg80211_get_channel: chanspec failed (-5) > > There is also an error creating the P2P interface: > > brcmf_cfg80211_add_iface: add iface p2p-dev-wlp2s0 type 10 failed: err=-52 > > I tried reloading the driver using: > > sudo modprobe -r brcmfmac_wcc > sudo modprobe -r brcmfmac > sudo modprobe brcmfmac > > The driver and firmware loaded again, but Wi-Fi remained unusable. > > The firmware files are present under /lib/firmware/brcm/, and the > firmware version reported by the driver is the same on the working and > failing kernels. > > The brcmfmac module metadata differs between the kernels: > > Working kernel 7.2.11-3-t2-noble: > srcversion: 3B6176FDB720DDE8E7C596B > > Failing kernel 7.3.0-2-t2-noble: > srcversion: 3DCA38D52402541701276CF > > I did not find obvious PCIe AER or fatal errors in the failing boot's > kernel log. > > It has been suggested testing intel_iommu=off after reloading > brcmfmac. The driver reload did not help, but booting with > intel_iommu=off restored Wi-Fi. > > This strongly suggests an interaction between Intel IOMMU handling and > the BCM4355/brcmfmac driver in the 7.3.0-2-t2-noble kernel. > > I have not tested a vanilla upstream kernel, so I cannot yet confirm > whether this reproduces outside the T2 kernel packages. Unfortunately, > I have limited time available for further testing, so I may not be > able to investigate additional requests promptly. I wanted to report > the reproducible behaviour and the intel_iommu=off workaround in case > it helps identify the regression. > > Could you advise on further diagnostics, or whether this should be > investigated as an IOMMU or brcmfmac regression? > > Thank you. > Can you reproduce this issue with the mainline kernel? Do you see any IOMMU fault messages in the kernel log? You can check by running: # dmesg | grep DMAR Have you tried narrowing down the cause with boot options such as iommu=pt or intel_iommu=on,sm_off? Thanks, baolu