From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 CE7D94F796E; Wed, 30 Sep 2026 16:03:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790784223; cv=none; b=q5l7YGXoc8Z5whSq+YZhbBFYbqBpN4IzGtCtvx+/RRiIw2c8Nt9Foc4NwdaUwwVfuUpnmL3TMYDi7Ls4Quyz6nNkYrjNhj9W9L80OxmBGBxVEgC/s8owPz73Uz8UYRsYt51L8bJ++uZTcjcbeXxTGdViSCppa6wmaBYniMezFfA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790784223; c=relaxed/simple; bh=xmur5MSj3jjTId8NTu8vgJzubyYkpXDGdHC9ufYORTw=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=EJnJbheWgaio2Pw9zTwz3+JwLG5b8xCQHay4lTav0T7vIInk/XJZ8+uz+L5XuVQvIJX8n1rpXpI7JmMMpsyfICa4fqVD4RlCrQrUbdIBvPDI/4pqa3CdOHjIa8AMRkH9ePwUOQgezJ6+BXX4+6JaMfhOC1VFJg7NDCwtBVIAcHw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=RE/dzkua; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="RE/dzkua" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 26DDF1F00898; Wed, 30 Sep 2026 16:03:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1790784218; bh=V0H94WaiDU58kRqrjjFb15HCR5gS4vQmxe3Vcc54tpE=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=RE/dzkuaIdZEuGNQlPN7yHUCHzY60acvd6sXGK1o068QXexKJw/0I3/16JSoXpkGz xlmCpmoaPjsJ7KKRfh6RSLBQniL9hcmdB+roRjZubba0oT0rg56OJsdREgW8YmGmpt QDkzBv1VlOXRQigGXGh3mTI+NhdeW2b7GshXSD/8= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Dave Carey , Sasha Levin Subject: [PATCH 6.1 079/982] USB: cdc-acm: start bulk-IN polling when ALWAYS_POLL_CTRL is set Date: Wed, 30 Sep 2026 17:13:35 +0200 Message-ID: <20260930152418.505519023@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260930152416.775402466@linuxfoundation.org> References: <20260930152416.775402466@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Dave Carey [ Upstream commit e5ab27ddd74e2d67a94c51c6f2ad87b1ff13912b ] The INGENIC 17EF:6161 touchscreen composite device has a ~55-second watchdog that resets the USB device if the bulk-IN endpoint on the CDC data interface goes unread. The existing ALWAYS_POLL_CTRL quirk keeps the notification endpoint (ctrlurb / EP 0x82) polling continuously, but that alone is insufficient: the firmware monitors bulk-IN activity, not just notification-endpoint activity. Add acm_submit_read_urbs() calls to the two ALWAYS_POLL_CTRL paths that already restart the ctrlurb: 1. acm_probe(): start bulk reads at probe time alongside the ctrlurb, so the watchdog is satisfied from first bind without requiring a userspace process to open /dev/ttyACMn. 2. acm_port_shutdown(): restart bulk reads after port close alongside the ctrlurb restart, so the watchdog keeps running when the last TTY user closes the port. acm_read_bulk_callback() already resubmits each URB unconditionally on normal completion, so once submitted the reads remain active until an explicit kill (disconnect, suspend). acm_submit_read_urb() is a no-op for URBs that are already in flight (read_urbs_free bit clear), so the existing acm_port_activate() call remains correct and races are avoided. Tested on Lenovo Yoga Book 9 14IAH10 (83KJ): without this patch the device resets every ~55 s when no TTY is open; with it the device remains stable indefinitely. Signed-off-by: Dave Carey Link: https://patch.msgid.link/20260515141940.751397-1-carvsdriver@gmail.com Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin --- drivers/usb/class/cdc-acm.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c index d1c8f620596d8..9ff5feceadad4 100644 --- a/drivers/usb/class/cdc-acm.c +++ b/drivers/usb/class/cdc-acm.c @@ -786,6 +786,9 @@ static void acm_port_shutdown(struct tty_port *port) "ctrl polling restart failed after port close\n"); /* port_shutdown() cleared DTR/RTS; restore them */ acm_set_control(acm, USB_CDC_CTRL_DTR | USB_CDC_CTRL_RTS); + if (acm_submit_read_urbs(acm, GFP_KERNEL)) + dev_dbg(&acm->control->dev, + "read urb restart failed after port close\n"); } } @@ -1539,6 +1542,9 @@ static int acm_probe(struct usb_interface *intf, if (usb_submit_urb(acm->ctrlurb, GFP_KERNEL)) dev_warn(&intf->dev, "failed to start persistent ctrl polling\n"); + if (acm_submit_read_urbs(acm, GFP_KERNEL)) + dev_warn(&intf->dev, + "failed to start persistent bulk read polling\n"); } return 0; -- 2.53.0