From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp2.iinet.com (smtp2.iinet.com [52.129.46.36]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 90A7838DC44; Sat, 17 Oct 2026 15:56:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=52.129.46.36 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792252580; cv=none; b=mbE/y1PA0IjiS+y+jMwTeGXZ+dTZLa+zKmtEEolZMRde19choxTWkJ0DQABpqYsePuE/fydvFcfjp0B8dRQczRlMb33mJRCFvL1A6ZsdFeA/hTPHlfkkHUjwFMjOhKmfRZSiBKcPHfxPDHlvgl7TCi63Uc0GzIiaixBhMO38PUQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792252580; c=relaxed/simple; bh=8p2lca59Kr/sPXCKE0RC6oNDFhBqdb/jXD9F09ecVvs=; h=MIME-Version:Date:From:To:Cc:Subject:In-Reply-To:References: Message-ID:Content-Type; b=UATTaM2UKEgdl46xhIbpdfRKK2y6nxRpgNAu8MX7DnVRJnodW2GBE9QyxCSdWTxwoWV1iEe9QshVE9GRyId13Tz0aR17AXc9/oF02dqbhuKZmXXArLNBvVzdyq5t/TV/PFJ9fvA95sxAL+KUsZc/yJ1Avq9DTyncovmsiSeSKNA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=nwlink.com; spf=pass smtp.mailfrom=nwlink.com; dkim=pass (2048-bit key) header.d=nwlink.com header.i=@nwlink.com header.b=XAwKO+Zv; arc=none smtp.client-ip=52.129.46.36 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=nwlink.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=nwlink.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=nwlink.com header.i=@nwlink.com header.b="XAwKO+Zv" Received: from webmail.iinet.com (web1.iinet.com [52.129.46.51]) (Authenticated sender: kaf@nwlink.com) by smtp2.iinet.com (Postfix) with ESMTPA id F4024B42BD1; Sat, 17 Oct 2026 08:56:17 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nwlink.com; s=mail; t=1792252578; bh=wOC3z8d3unpvQdUfL2bvr+OorEHjTzNQZKSBDptrq6I=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=XAwKO+ZvEyUqx00zvjmuaTE/L9dRem0ramAaHSewGTTBAzjCD1A+fEG8pR4XFg4Dm gUJY8aXJ43X5SOn1D0iVJj0pu/g9Jy/JF2aAyAR+ORSAykMZQ2VKylEczL9aJXPJ8D BUGyrH7162eWdGVa42ZU9XxmFza+eiRzzFH/Z8J7HcEyF8SXGquOOZWV6T3Wx53pow znAbaT33WQAGu89m/spHLSHFidV9PJu0DvNw9OOGec2h2On7EmTMB6hdI1fVEErsrd DSUeLBfVDkTSRkjazJQZ4l9T3A3CNv+NXBYiWVEU2KSl7YFRO4fLHCTJdL6PtNnvZA f5L9gR6Y2wVhw== Received: from c-98-203-133-45.hsd1.wa.comcast.net ([98.203.133.45]) by webmail.iinet.com with HTTP (HTTP/1.1 POST); Sat, 17 Oct 2026 08:56:15 -0700 Precedence: bulk X-Mailing-List: linux-usb@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Date: Sat, 17 Oct 2026 08:56:15 -0700 From: kaf@nwlink.com To: Greg Kroah-Hartman Cc: linux-usb@vger.kernel.org, Jonathan Corbet , Shuah Khan , linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org Subject: Re: [PATCH v2 0/2 RESEND] usb: gadget: uac2: support explicit channel counts In-Reply-To: <2026101742-ouch-sensually-f5a4@gregkh> References: <20261016162534.384844-1-kaf@nwlink.com> <2026101742-ouch-sensually-f5a4@gregkh> User-Agent: Roundcube Webmail/1.4.3 Message-ID: X-Sender: kaf@nwlink.com Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit On 2026-10-17 01:05, Greg Kroah-Hartman wrote: > On Fri, Oct 16, 2026 at 09:25:32AM -0700, Kyle Farrell wrote: >> USB Audio Class 2.0 permits up to 255 channels in an audio channel >> cluster >> via bNrChannels. Independently, a channel-location bitmap is specified >> via >> bmChannelConfig for up to 27 predefined spatial locations. Setting >> bmChannelConfig to zero indicates that the channels have no predefined >> spatial positions. >> >> The current UAC2 gadget driver derives bNrChannels from the number of >> set >> bits in bmChannelConfig. Since bmChannelConfig provides 27 predefined >> spatial locations this limits playback and capture streams to 27 >> channels. >> >> This series allows channel counts up to the UAC2 limit of 255 without >> requiring predefined spatial channel locations in bmChannelConfig. >> Existing ConfigFS channel-mask configuration continues to work >> unchanged. >> New optional playback and capture count attributes allow the number of >> channels to be specified separately from the channel-location bitmap. >> >> The series is split so that the shared u_audio infrastructure is >> updated >> first without changing behavior, followed by the UAC2 functional >> change. >> >> Patch 1: >> Pass resolved playback and capture channel counts explicitly into >> the UAC1/UAC2 shared u_audio implementation instead of deriving them >> from channel masks. >> >> Patch 2: >> Add ConfigFS playback/capture channel-count attributes to the UAC2 >> function driver and use them when generating descriptors and stream >> configuration, allowing counts beyond the 27 predefined channel >> locations. >> >> Testing >> >> Testing was performed using a Raspberry Pi Zero 2 W configured as a >> USB >> UAC2 gadget. Streaming and descriptor validation were performed >> against >> both Linux and macOS hosts. Windows hosts were not tested. >> >> UAC1 >> - Verified playback/capture operation via alsaloop. >> - No descriptor or behavioral changes observed. >> >> UAC2 >> - Verified legacy channel-mask configuration (1-27 channels). >> - Verified explicit channel-count mode with 2, 28, 61, 62, 96 >> channels. >> - Verified invalid channel-count/channel-mask combinations are >> rejected. >> - Verified Feature Unit descriptor size limits at 61/62 channel >> boundary. >> - Verified descriptors including: >> * bNrChannels >> * bmChannelConfig >> * Feature Unit presence and bLength >> * AudioControl wTotalLength >> * endpoint wMaxPacketSize >> - Verified ALSA-reported playback and capture channel counts. >> - Verified streaming using alsaloop. >> >> Changes in v2: >> - Edit commit messages for clarity and brevity. >> - Add Assisted-by: LLM attribution. >> - No code changes. > > Why was RESEND needed here? Saying that would be nice. > > Also, sashiko points out a number of problems... > > thanks, > > greg k-h I resent v2 as both it and v1 had received no review. I should have stated that in the cover letter. I'm reviewing the Sashiko findings and will address relevant issues before submitting a revised series. Thanks, Kyle