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 5F6A018EAB for ; Thu, 6 Nov 2025 03:52:49 +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=1762401169; cv=none; b=Lof57Oq3/2eG7SwOqY+eZxTdVwxdcwZC4YaQ9WWfLVnkGO49Na3o5c7xZAoIaxkWJHLihQRge/G04LDbq2IjdVPAVZENLO92RtdBOhsuf0EYie17CfLkdA2Gp0gmLUAJBjCd+HCzF30k6u/WCQpMPX9FOU4bDglOku0c7E6Evt4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762401169; c=relaxed/simple; bh=x4o9wpV5pvcCyXWyeeqqM71i3UD0E6rXxzw3fqINVKU=; h=From:To:Subject:Date:Message-ID:In-Reply-To:References: Content-Type:MIME-Version; b=G97u8VzLIfZBpImejK33pxcbn366ER3Tkz9muKMSpOeXTWfh9bOGobtkipANYe3zeKl/mYeWksLz4OKfPeuOplb4TOiuUbd82rTWfbX4OHB/8H1JLvgSAzx3pxpDVAp6SnBfSQ0p9Qsk2Ee/v8caa/nQVx+FLdI7dO8LYY7lYgQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=hzR+WOmb; 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="hzR+WOmb" Received: by smtp.kernel.org (Postfix) with ESMTPS id E6CE2C116D0 for ; Thu, 6 Nov 2025 03:52:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1762401168; bh=x4o9wpV5pvcCyXWyeeqqM71i3UD0E6rXxzw3fqINVKU=; h=From:To:Subject:Date:In-Reply-To:References:From; b=hzR+WOmb6WPSmD0TZK7CYohgPo84IqgKaQRaeTSDFMcFLlpGFdzm2lvuvH6+ILksO w2YzWoFcKG+0ENp8bAT3ruJOwz/phUu1eMdTorj2xopGaAuIqw7OCxiGzIbfYqXA1t zIA9eMseJ0y3pA/4He6yp8w+OZTkLpbfHLcjlaJB+fq49dSkqKQ5O/wJ9nrm2lesho MwJbXg31F/YTCZHzyFdMZNLbqJ5hDBtTDw4GDGu/u+EkV67oN2/isYil/8XnpIGCx2 sqRidgLiVW5hXMjKSe1bscZ8aA6R+lfJSXdTIvWTw8gce+NF5P/sF7AVUbSzAzg+R/ 9K4My+SWw3AFg== Received: by aws-us-west-2-korg-bugzilla-1.web.codeaurora.org (Postfix, from userid 48) id E30D7C4160E; Thu, 6 Nov 2025 03:52:48 +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: Thu, 06 Nov 2025 03:52:48 +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: stern@rowland.harvard.edu 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 #10 from Alan Stern (stern@rowland.harvard.edu) --- Figuring out how to handle isochronous transfers has been very difficult; i= t's not obvious what scheme would work best. Compounding that difficulty is the fact that different host controller drivers store their (micro)frame numbers differently, so drivers will never know exactly what to expect. You say that uhci-hcd used to work "the intuitive way", but in fact experie= nce has shown that no way is truly intuitive. Or to put it another differently, what's intuitive for one person is not intuitive for another. And don't forget that host controller drivers have to handle isochronous endpoint queues that can be in three or four different possible states: emp= ty, partially or completely full, and partially full but totally expired. It's= not at all easy to come up with a set of flags and values that can handle all t= he possibilities in ways that drivers will find convenient to use. The matter of specifying polling intervals different from what the endpoint descriptor says is yet another can of worms. For example, host controllers generally can't change polling intervals in mid-stream. And some might res= erve the necessary bandwidth at the time when the alternate setting is installed, before any URBs have been submitted -- how would one go about changing it f= rom the default value then? --=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.=