From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 871983438AC for ; Sat, 30 May 2026 16:23:06 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780158186; cv=none; b=oBApzg5YpY3MzSCo3g1toBhvTJ74fiFVZ1qSos7jSAozHMbHs7+J7CNHd7jfINOj74slq8yRfO3s9EV8dphsoH0ftNDKYRK1xdG6RW5cHlHJ2WhzU4I5Ip652Bl0ZRYSj4MO28Gsw/8G21KlVz3S/QY2g4KinPlq0OzrbG7btnU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780158186; c=relaxed/simple; bh=K9b8KgxsQjqDa3/vkbDak4JojqvjvixzVevKD4AOXMc=; h=From:To:Subject:Date:Message-ID:In-Reply-To:References: Content-Type:MIME-Version; b=uOrGgjdM1M0XWRuMEz2f+SpXoWxGw+i92GRperwq/eYFmRVr1+xcFMu3Orqw2Ffct4WptvkvcApK2E87l10KxY5l3bUvSmpZrAPOCFFvLbnQuIY3C8sNZ+TH0LL0OMFXbnw0s3KPhHkz0uXVrBvgV69+hq9hQs6DG90ZWUtjpIU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=nmZ89t7z; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="nmZ89t7z" Received: by smtp.kernel.org (Postfix) with ESMTPS id 2C7F4C2BCC4 for ; Sat, 30 May 2026 16:23:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1780158186; bh=K9b8KgxsQjqDa3/vkbDak4JojqvjvixzVevKD4AOXMc=; h=From:To:Subject:Date:In-Reply-To:References:From; b=nmZ89t7zqsJRNr/rCOAgaJy/LplfBDbvgDx+MtBCOkcvyVvax+yPDaRwqkjEoVId0 J0wy+qnapIrsdeJNkKaKKNFbiSd5/oPsL2mkveV0TApuswBPOPZCfSIU82hqqhS22n 3RGZ9S49Quzxfp5Tl2PQcU+MxTaz9Sp5eP2L5+6bA+d0i28FQjwITj2SSx298U5YmD 7BKkM2vYriGM1xpIiJrMciUnn88sepZBGDqURxIJ6b+EERpIdXFsmIWXio+Xe02wEY krRr/jhtupBIpLGTzvZUtc6ubwWgmgwooZp2MBAno9N6uInX+dfuP88+wPuIY781Yn 7eEKEknmeG0mA== Received: by aws-us-west-2-korg-bugzilla-1.web.codeaurora.org (Postfix, from userid 48) id 24405C3279F; Sat, 30 May 2026 16:23:06 +0000 (UTC) From: bugzilla-daemon@kernel.org To: linux-bluetooth@vger.kernel.org Subject: [Bug 221598] Bluetooth: btusb/btrtl RTL8821C 0bda:c821 HFP/mSBC microphone stutters with bursty SCO RX delivery Date: Sat, 30 May 2026 16:23:06 +0000 X-Bugzilla-Reason: AssignedTo X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: Drivers X-Bugzilla-Component: Bluetooth X-Bugzilla-Version: 2.5 X-Bugzilla-Keywords: X-Bugzilla-Severity: normal X-Bugzilla-Who: apocarteres@gmail.com X-Bugzilla-Status: NEW X-Bugzilla-Resolution: X-Bugzilla-Priority: P3 X-Bugzilla-Assigned-To: linux-bluetooth@vger.kernel.org X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: Message-ID: In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Bugzilla-URL: https://bugzilla.kernel.org/ Auto-Submitted: auto-generated Precedence: bulk X-Mailing-List: linux-bluetooth@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 https://bugzilla.kernel.org/show_bug.cgi?id=3D221598 --- Comment #6 from Alexander Paderin (apocarteres@gmail.com) --- Additional binary usbmon evidence =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D I captured the same HFP/mSBC failure with simultaneous btmon and binary usb= mon. New files: ``` captures/btmon-20260530-191225.snoop captures/usbmon-bus3-dev7-ep3-20260530-191228.jsonl.gz reports/captures-sco-analysis.md reports/usbmon-bin-analysis.md reports/usbmon-bin-anomalies.csv ``` The binary usbmon capture was taken from `/dev/usbmon3`, filtered to Blueto= oth device `3-007`, isochronous endpoint 3. It includes full ISO descriptors and payload data, unlike the debugfs text usbmon log. Important result: ``` usbmon-bus3-dev7-ep3-20260530-191228.jsonl.gz RX USB IN completions: reconstructed ISO fragments: 12675 x 25 bytes reconstructed HCI SCO packets: 4225/4225 valid, handle 5 H2/mSBC markers: 5038 H2 bad sequence: 23 H2 same sequence: 21 H2 bad distance: 20 TX USB OUT submissions: reconstructed ISO fragments: 12669 x 25 bytes reconstructed HCI SCO packets: 4223/4223 valid, handle 5 H2/mSBC markers: 5068 H2 bad sequence: 0 H2 same sequence: 0 H2 bad distance: 0 ``` The simultaneous btmon capture shows a matching RX-only problem: ``` btmon-20260530-191225.snoop RX: packets: 3963 x dlen 72 <1ms packet intervals: 20.0% >15ms packet intervals: 10.0% H2 bad sequence: 21 H2 same sequence: 20 H2 bad distance: 17 TX: packets: 3961 x dlen 72 H2 bad sequence: 0 H2 same sequence: 0 H2 bad distance: 0 ``` This suggests that the H2/mSBC sequence corruption is already visible in the USB ISO IN data delivered to the host, before PipeWire/WirePlumber and befo= re userspace. It also makes the repeated near-identical btmon RX timestamps le= ss important by themselves: the USB IN side is batched in 10 ISO descriptors p= er URB, so several 1 ms USB frames are naturally processed together by one URB completion. The remaining question appears to be whether the controller/firmware is delivering duplicated/missing mSBC frames on RX, or whether the Linux btusb/btrtl setup for this controller causes the controller to use bad SCO/= eSCO parameters. The next useful comparison would be a Windows USBPcap trace of = the same HFP/mSBC scenario, especially the vendor initialization commands, sele= cted USB alternate setting, and `Setup Synchronous Connection` parameters. Attached archive: `bluetooth-rtl8821c-binary-usbmon-update-2026-05-30.tar.x= z` --=20 You may reply to this email to add a comment. You are receiving this mail because: You are the assignee for the bug.=