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 ED7E54848BD; Thu, 17 Sep 2026 16:51:31 +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=1789663893; cv=none; b=T/iMDv10y+8GgxMkyhxpNUWTlHYG+9JOVG6BU8B+45aldpWNikApPwl82zf7bB721TH8gpFhbvs9BQuTOYfHgiJUlmPY/Hmvv82MyCicWfLTzSX5smKWSiFRm1Q52SVduVHgHyBid8Iv2qnSrdJVHImj0D48eykCi7Fikpqmzzc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789663893; c=relaxed/simple; bh=KpnWF9CAsDV13N1Bsy/XN4vrKIv4XFwc5oeQd5+HMj0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=K9NT2vALquvjSoSFteNrqtWgro77nMAqvgWkmb0cjOBJCxAFU1m0hGo3SqJH537S8c1zthsUAbw4q8dyD7fEcZ2xG+MbfwNYXrmOmsdxpJmeQW7eUNqSTotN2Hs9BpiJxAbWvJDxREva6pqynpIuev6JSCPqFHXkmK99O2Y+Gng= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=m81wF+mi; 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="m81wF+mi" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4F9E31F00893; Thu, 17 Sep 2026 16:51:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1789663891; bh=WMQ/uoUaqPo1zovcWt5HQV4EUgUthdNqNPlHRqOfJlY=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=m81wF+mia51vsdsQihKbMJXdu4RVLcjNgPHAtQEWYo88VPY6scbQ3+C9GFDlReuob +CzjXZg6jCsOz9MGoaWed5YyOqWEiwiVK9Ob8jcGsb1i456GuTgFxdwWlseaxt6tiW U9gUIUfsj4JezLnA8P2A5KHOMSKRtXl5JeG/PSWo= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Dave Carey , Sasha Levin Subject: [PATCH 6.18 0189/1250] USB: cdc-acm: start bulk-IN polling when ALWAYS_POLL_CTRL is set Date: Thu, 17 Sep 2026 15:59:44 +0100 Message-ID: <20260917151557.239533091@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260917151551.901433442@linuxfoundation.org> References: <20260917151551.901433442@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 6.18-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 12f9fe62199ba..d6a2f1591460a 100644 --- a/drivers/usb/class/cdc-acm.c +++ b/drivers/usb/class/cdc-acm.c @@ -797,6 +797,9 @@ 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"); } } @@ -1564,6 +1567,9 @@ 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