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 93E2323F424 for ; Wed, 5 Nov 2025 21:18:29 +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=1762377509; cv=none; b=mKFAnrJYZTKy2FfGLKx5QLbaMJ6woQGal+tFL20Caf/mnG8e6Co05E685Xvf5qEgboZ4ShCG6vlrm30tT31XYEScoHgV/Ml2TTS8qKAQS0UOzsX2kCcnOHfzoIFXYaa2+dyFUD+per30hHXZpmhZjhPi/vWpM8p7zeCFbPzjVvg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762377509; c=relaxed/simple; bh=jgJanJDq/uAJzRdZnbfYOBZ0uvfGpBdHGQ0qW3pMLSE=; h=From:To:Subject:Date:Message-ID:In-Reply-To:References: Content-Type:MIME-Version; b=pTVRXzGZ+XAqLMj2TuKoE67ff2bfC0vF1mxk3bFAcmDrEewBrqWNNH5n2X2VkMScsUAHXpEJHxvAPCj9mnK7b+BsZKsYx23AY8hTCcR7CebHAx8YzJawDBOetC7/5uo/HEuHQVjZETMboSTY3n9+dV6V9Hd7Ql8sXj7k0IF4t2w= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=PrX/G+HA; 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="PrX/G+HA" Received: by smtp.kernel.org (Postfix) with ESMTPS id 32E3AC4CEF5 for ; Wed, 5 Nov 2025 21:18:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1762377509; bh=jgJanJDq/uAJzRdZnbfYOBZ0uvfGpBdHGQ0qW3pMLSE=; h=From:To:Subject:Date:In-Reply-To:References:From; b=PrX/G+HAY0ofvPabjQ6oixReYlx5GsRhAEoI+rWPfgodLqO+SKqIwLA6decN0/FNn 0rs2MVfIMnl5UmQ/mi1kpxbJiIHLac1S6oZh9bsq3+dqJ5toOfcsvcXVhTXJZvZoZp cnDy5ULJ2sm3tK1e0Df5ga2ScEJm3hNPDNgdTsfZSsqhZafKNoDudfjxVFcE+WMH4l FNQIkG+hknIDWRyBXVuGdgC4VtWjXOtqB5Q9UGuM0GmnEFr9TB2dtfV8rAfHWl9MQ9 gcZb6RIbTAhjdn9JIZOCULZdHrv+5QJdf8sf9Joq7TfHk4jvbZMTsz5lII++w36+3a MdKWyDqvtrW1A== Received: by aws-us-west-2-korg-bugzilla-1.web.codeaurora.org (Postfix, from userid 48) id 2C3E8C433E1; Wed, 5 Nov 2025 21:18:29 +0000 (UTC) From: bugzilla-daemon@kernel.org To: linux-usb@vger.kernel.org Subject: [Bug 220748] usb: xhci_queue_isoc_tx_prepare ignore start_frame and always assumes URB_ISO_ASAP is set Date: Wed, 05 Nov 2025 21:18:28 +0000 X-Bugzilla-Reason: None X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: AssignedTo drivers_usb@kernel-bugs.kernel.org X-Bugzilla-Product: Drivers X-Bugzilla-Component: USB X-Bugzilla-Version: 2.5 X-Bugzilla-Keywords: X-Bugzilla-Severity: normal X-Bugzilla-Who: michal.pecio@gmail.com X-Bugzilla-Status: NEW X-Bugzilla-Resolution: X-Bugzilla-Priority: P3 X-Bugzilla-Assigned-To: drivers_usb@kernel-bugs.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-usb@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 https://bugzilla.kernel.org/show_bug.cgi?id=3D220748 --- Comment #9 from Micha=C5=82 Pecio (michal.pecio@gmail.com) --- Thanks Alan, that's good to know, because Documentation/ is horribly out of date and the kerneldoc doesn't really say that this field is ignored as inp= ut. (Also, it says that if the whole URB is already expired, it would fail to submit, but this behavior was apparently later changed to completing with -EXDEV). After a bit of digging, I see that urb->start_frame and URB_ISO_ASAP used to actually work the intuitive way on UHCI in early 2000s, but then EHCI began= to act as if ASAP is always set, xHCI got the same behavior, UHCI was converte= d to EHCI behavior, and ASAP got a new and different meaning. So today it is unrealistic to expect host controller drivers to respect start_frame, class drivers aren't setting it to anything meaningful, and the patch I suggested earlier would likely break some class drivers unless a new flag separate from URB_ISO_ASAP is added to force using the requested start_frame. I still wonder if providing means of overriding the polling interval wouldn= 't be easier overall (less changes to snd-usb-audio required to support this n= ew HW). --=20 You may reply to this email to add a comment. You are receiving this mail because: You are watching the assignee of the bug.=