From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=91.218.175.134 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1792498145; b=HDEXDTqY+xcgwSydf6vbL6qlVuQ/IHSmVTPlhZl1tJ1qpIIEsvF79jNGbMMyEedEU9bk Mq6Jl53nSzldT3ac38UtsnaBiyBv0jRv5mn9RFlAqZQIIRdGhzsuXDhu12g427FgGrmsk +DMdI+BZYDq6tryzndnX+WdGY1Tzl162GQ4agrOsF8C1T1AkOnakLxyIIdnVViOYHwdDN p6NcXqPMzugH3AMFPU2W6SUyVfZrjTaKPOGlx6Ku9zrgaco1ox3phJqMUYAMoiqgHEt4i yJRH+ALn2T3/PblDZmsqmRZkCq2uK8WWD7e4lwhY5gT6AOOgtAmYw763eBeeRMgDtRQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1792498145; h=DMARC-Filter:X-Envelope-To:DKIM-Signature:X-Envelope-To:Received: X-Mizu-Trace-ID:X-Migadu-Flow:Message-ID:Date:MIME-Version:User-Agent: Subject:To:Cc:References:Content-Language:From:In-Reply-To: Content-Type:Content-Transfer-Encoding; bh=2oAYJPU4rS/B67nm2olDeHtopzXuD57QG29t513sHn8=; b=OxaUG6HjF8rjaX9ccw4WPybGi3pKaP7EW8oke/0svznSzLk52xbBoUue0Qc85QOLSruX Ji6coAY0d9kLpi5PFiYpWrPciWkxu9C90deH8UtZlX9+ZTAt3Giyylt0VuZVBRgvu7YPF xFp671wD8ipY5NWDMj6TGiHaDIvNKQKeMjuYX+3BGhsN4kkKTc1wZDQboenxUgjz/M9Pa DcZia1YvdhIdITEpLdJ2w8xztnvWHGIoZ46jRT/SgdAM3JGaLmy4jjKcB0Pkp3rHK6GYF M+mcER5/70BCqBhnb97+SbZvGMKju49+JiYC1rGlSb7apwPoTnsU80DdJly+s+jEmfg== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass header.d=linux.dev header.i=@linux.dev header.a=rsa-sha256 header.s=key1 header.b=M+7uNKlk; arc=none smtp.remote-ip=91.218.175.134 Received: from mta0.migadu.com (out-134.mta0.migadu.com [91.218.175.134]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id ACE2E606A325 for ; Tue, 20 Oct 2026 12:08:59 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org ACE2E606A325 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linux.dev header.i=@linux.dev header.a=rsa-sha256 header.s=key1 header.b=M+7uNKlk X-Envelope-To: linux-wireless@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=NHvbn3ue2nkgb328laFkEqNkxDgGzunCyN1UR3R7YQU=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1792498137; v=1; x=1793102937; b=M+7uNKlkKoX7RObvP2s1ErlPC3SXJKgoI5mhc+dVsQucAfnZ7p0hFStgvI4PQIG0zg3ZaXUJ mnf2X2kVupOb9V5zUa0nZC46vyb/7n54WVky3aeQSTtu0UMUQLejzv/ERU35Fl4klH53WoIYL/C zkOYUg95KIvHCfrKDWXCYd60= X-Envelope-To: linux-wireless@vger.kernel.org Received: by smtp.migadu.com with ESMTPS id cac925beb0231a6d; Tue, 20 Oct 2026 12:08:57 +0000 X-Mizu-Trace-ID: cac925beb0231a6d X-Migadu-Flow: FLOW_OUT Message-ID: Date: Tue, 20 Oct 2026 17:38:44 +0530 X-Mailing-List: linux-wireless@vger.kernel.org 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, jgg@nvidia.com, kevin.tian@intel.com, joro@8bytes.org, will@kernel.org, robin.murphy@arm.com, dwmw2@infradead.org, baolu.lu@linux.intel.com, linux-kernel@vger.kernel.org References: Content-Language: en-US From: Aditya Garg In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 20/10/26 5:19 pm, Peter Kiddier wrote: > Adding the IOMMU maintainers and linux-kernel. > > The original report and test results are below for context. > > I haven't tested a vanilla upstream kernel, and may have limited time > for further testing, but wanted to share the findings in case they're > useful. > > Thank you. https://www.mail-archive.com/ubuntu-bugs@lists.ubuntu.com/info.html Similar issue is present in older non T2 Macs, so definitely not a T2 patches issue. Also, T2 patches do not touch IOMMU or brcmfmac > > > On Tue, 20 Oct 2026 at 22:32, 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.