From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from rtits2.realtek.com.tw (rtits2.realtek.com [211.75.126.72]) (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 7201E274652; Tue, 12 May 2026 01:25:41 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=211.75.126.72 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778549143; cv=none; b=tNUIx9JgTbHddr6D3r056atpb7Uema0Yn4qEpLH2Z2T8ksMhQPR4O0dZnX9Py1iYQSLxoK128bsYKJlQOfIw6t7ILuWfVMdl7eqLtktcWUvOhBEWrZudLtI12VyVXRBzRiJA+PLz9qfMNiVJplg7x6HV4wv/Mzd+K7XSVvDf8Zk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778549143; c=relaxed/simple; bh=sD7THkCpyvctCNkFb8gP1aEmsezKLo+ZkzrPZYiiiUo=; h=From:To:CC:Subject:Date:Message-ID:References:In-Reply-To: Content-Type:MIME-Version; b=QYH+cP0fM5e2cRHSyJzFp3TVLU4hWgR0GLsv1hIzx249XNOQERMDQOzzogTo7Ed/LUvlV7Dz+LRJWdvxu8+86itSkGIziCH3x5s83GbnMNcn6j1yerfw+cKsmk3cm/6PJX7NYkBmuvrkEklZlJYHMuXdXgFaWmD2XKN2wnshQrU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=realtek.com; spf=pass smtp.mailfrom=realtek.com; dkim=pass (2048-bit key) header.d=realtek.com header.i=@realtek.com header.b=RNCKTdJl; arc=none smtp.client-ip=211.75.126.72 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=realtek.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=realtek.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=realtek.com header.i=@realtek.com header.b="RNCKTdJl" X-SpamFilter-By: ArmorX SpamTrap 5.80 with qID 64C1PFa743450606, This message is accepted by code: ctloc85258 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=realtek.com; s=dkim; t=1778549115; bh=xNkS2Oo1SRFZ1oqGWqT65dkADUGTE0syKdbbupWyRjo=; h=From:To:CC:Subject:Date:Message-ID:References:In-Reply-To: Content-Type:Content-Transfer-Encoding:MIME-Version; b=RNCKTdJlu+6UyMLbpLFdtTmVDUYqCUvTtVVBEKa5tQxBlyFj8l0NWoNYty5ql39o4 g6aV6BpGicNlgpWLoA0OCiiyPodfFaw7KvjF/T1m4+nHzCJPycgSFTrHrcmPRLXaYt iZ/CiLm7wgP18kOts94Og9rTIvrBPyMyYc9x6FCXu6+wh4WuzfDeTy56vE2KQcv31P nCWcLH3lXTId6NnckCHt9iwvGIgiO11+L1cgjAFpuH0GHTQdRdWDEsrYG4JDoSJl8B 3wGcoPMznw3bOU1tBkEK8QtVBbGcdv2k9zszUQuMrblmpQN8qRUeLGPwX/YD/zgH9r DDUwGGFDFAwUQ== Received: from mail.realtek.com (rtkexhmbs02.realtek.com.tw[172.21.6.41]) by rtits2.realtek.com.tw (8.15.2/3.27/5.94) with ESMTPS id 64C1PFa743450606 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 12 May 2026 09:25:15 +0800 Received: from RTKEXHMBS06.realtek.com.tw (10.21.1.56) by RTKEXHMBS02.realtek.com.tw (172.21.6.41) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.2562.17; Tue, 12 May 2026 09:25:16 +0800 Received: from RTKEXHMBS06.realtek.com.tw ([::1]) by RTKEXHMBS06.realtek.com.tw ([fe80::e6fd:5a3f:8946:92c4%10]) with mapi id 15.02.2562.017; Tue, 12 May 2026 09:25:16 +0800 From: Ping-Ke Shih To: Devin Wittmayer , "johannes@sipsolutions.net" , "linux-wireless@vger.kernel.org" CC: "rtl8821cerfe2@gmail.com" , "linux-kernel@vger.kernel.org" Subject: RE: [PATCH rtw-next v2 1/1] wifi: rtw89: usb: Support switching to USB 3 mode Thread-Topic: [PATCH rtw-next v2 1/1] wifi: rtw89: usb: Support switching to USB 3 mode Thread-Index: AQHc4WBnvzkVdckSH0mw5MmxdTZUKbYIjd+AgAAKT4CAAP2NcA== Date: Tue, 12 May 2026 01:25:16 +0000 Message-ID: References: <6d553cffcb0ae84e141006ae1430f6f37909ad2b.camel@sipsolutions.net> <20260511180351.26471-1-lucid_duck@justthetip.ca> In-Reply-To: <20260511180351.26471-1-lucid_duck@justthetip.ca> Accept-Language: en-US, zh-TW Content-Language: zh-TW Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Precedence: bulk X-Mailing-List: linux-wireless@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Devin Wittmayer wrote:=20 >=20 > On Mon, 2026-05-11 at 19:26 +0200, Johannes Berg wrote: > > > +static bool rtw89_switch_usb_mode =3D true; > > > +module_param_named(switch_usb_mode, rtw89_switch_usb_mode, bool, 064= 4); > > > +MODULE_PARM_DESC(switch_usb_mode, > > > + "Set to N to disable switching to USB 3 mode to avoid poten= tial interference in the 2.4 > GHz band (default: Y)"); > > > > We shouldn't really add new module parameters. This module parameter follows the pattern Bitterblue established for > rtw88: same user-facing name (switch_usb_mode), same description, same > default. Commit 315c23a64e99 "wifi: rtw88: usb: Support USB 3 with > RTL8822CU/RTL8822BU" (2024-07-10) added it to rtw88/usb.c and it > remains in-tree. I took the patch of rtw88 because we switch USB mode at probe stage, but USB 3 mode has interference on 2.4GHz band (as the comment says). If a user insist on 2.4GHz with a good performance, this is an option to keep USB 2 mode. >=20 > Three v3 paths I see: >=20 > 1. Drop the param. Users hitting USB3 2.4 GHz harmonic interference > would need to use a USB 2 port instead. > 2. Move the escape hatch behind a sysfs or nl80211 control. New UABI > surface; open to design suggestions on that. > 3. Keep it for rtw89/rtw88 symmetry on the same USB3 / 2.4 GHz > harmonic interference issue. An additional option might be to not support 2.4GHz channels when switching to USB 3. But I'm not really sure if it is acceptable to USB users. Ping-Ke