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 08F9D2561AD for ; Mon, 12 May 2025 07:15:11 +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=1747034113; cv=none; b=eAHVl3IXcK4quI0hxpYwUZSb4AEisaFyVacLRLITWjmaLvk+MYGgfAHUmv1aQkWPYFcYpeXbLG9NhTrrYtdAeiOf8mim9c7oIhCm5ZvgcxfecSRPghGn9R9A16yBMUTtFMY4uC9+fwhnLbKo8UrTUF8WNG4rwnv24xToLCJ5ZTI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747034113; c=relaxed/simple; bh=7dMk5qgIVTbtNel61vEWL54bj6uFYjb3FLQRzjHLibE=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=e34/Fsn+k8tBWLfILdOfXTLv/PGBta2gnYX7QzLvHMtKyr45XFKC/bV+jjA2En4opxfl7yvJ+OgUpmakGY4AXvlYOdZBvnjdc8edh7/sh2ukB9zUxpxL8kauuQuWTjDGoDvvb7Gx6/aHYkdXrd80Yg3TEOCB5IbeJGbwd+MEwGw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=spdqPApL; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="spdqPApL" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E45BEC4CEE7; Mon, 12 May 2025 07:15:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1747034111; bh=7dMk5qgIVTbtNel61vEWL54bj6uFYjb3FLQRzjHLibE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=spdqPApLwfMyG0Yy85f6+Nvu77RUqEUTyxiA64D2qq9Y3lBLjK8p2iAcxo2af7AMJ sueNxOVPnt0KrT7buyenmWXkGv6XxqIh25niCMWioUDASKoU07h8PyuG6yZKdbBlGD 7/GqZaXND3ZQ+TXuSgbEWBunzQUTT1f1gONQq1m8= Date: Mon, 12 May 2025 09:15:08 +0200 From: Greg KH To: Guan Wang Cc: mathias.nyman@linux.intel.com, linux-usb@vger.kernel.org, guan.wang.jy@renesas.com Subject: Re: [ISSUE REPORT] xHCI infinite endpoint reset loop on full-speed after transfer error Message-ID: <2025051244-rebuff-morphine-9808@gregkh> References: <20250512063912.3331082-1-guan.wang.jy@renesas.com> Precedence: bulk X-Mailing-List: linux-usb@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250512063912.3331082-1-guan.wang.jy@renesas.com> On Mon, May 12, 2025 at 02:39:13PM +0800, Guan Wang wrote: > From: Guan Wang > > Hello, > > Using Linux version 6.15.0-rc5-00032, I encountered an issue where the xHCI controller enters an > infinite loop while attempting to recover a USB endpoint. This causes the xHCI driver to get stuck, > and no USB transfers can proceed. > > This issue appears to only occur with full-speed bulk devices such as USB serial adapters(e.g., > USB-Serial or CDC-ACM class). I've reproduced it using CH340 and CP2102 USB serial devices. > > **Steps to reproduce:** > 1. Attach the device. > 2. Start continuous data transfer (e.g., `cat /dev/ttyUSB0`). > 3. Induce transfer errors via: > - EMI interference > - Sudden temperature changes > - Long USB cables > - Briefly shorting DP/DM lines to simulate a transaction error > > After this, the xHCI controller enters an infinite reset loop on the affected endpoint. "Transfer error" > messages continuously appear in the logs, creating a log storm. The issue seems to improve or disappear > when an external high-speed USB hub is inserted between the host and device. > > Do you have any comments or suggestions? The log is shown below: > > > **USB emulation dmesg** > > [ 41.109377] usb 3-1: new full-speed USB device number 2 using xhci-renesas-hcd > [ 41.277651] xhci-renesas-hcd ee000000.usb: add ep 0x82, slot id 1, new drop flags = 0x0, new add flags = 0x21 > [ 41.277676] xhci-renesas-hcd ee000000.usb: add ep 0x2, slot id 1, new drop flags = 0x0, new add flags = 0x31 > [ 41.277697] xhci-renesas-hcd ee000000.usb: add ep 0x81, slot id 1, new drop flags = 0x0, new add flags = 0x39 Does this happen on other xhci controllers as well? Or just the Renesas chip? thanks, greg k-h