From patchwork Mon Apr 12 09:38:13 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Johan Hovold X-Patchwork-Id: 12197459 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-19.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 468CAC433B4 for ; Mon, 12 Apr 2021 09:45:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1B0FE61247 for ; Mon, 12 Apr 2021 09:45:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240664AbhDLJpl (ORCPT ); Mon, 12 Apr 2021 05:45:41 -0400 Received: from mail.kernel.org ([198.145.29.99]:55820 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238880AbhDLJjB (ORCPT ); Mon, 12 Apr 2021 05:39:01 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 37BCF61249; Mon, 12 Apr 2021 09:38:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1618220314; bh=t9qOhZ9FiANoiUN/D2w9FYQpykHnyvkO6VLNd1kcNIE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=PQl7zFERbr4YPhig/YkCw5KTqMJtSP0h1rInTvaAR84TTkMLUukYVaItTHyOMoZeK hk9vXcxyU4LC3HaMYxadVi9I/PXIaEdMlvjttyDVddiFGPnEbnAL5ZmESVOf0CFI// YHNn3mpSMjbJ5E10sRoPZME7IW0BnbqSSDUYdkcLCbHGw3O/6qPCUnRSyJ4XN9Ahtm RLZRYhlFAUAla+YYwJJALqgNlccOglrZAkNwQnDCSjWsf7whzSBq7CjOKe5t7FHYQm 8MJNIkdblGc/+XJvw31HFEt40XMMziLlYmRZgiobLe0pdYsf2WedGAC+4CFV54KgPU QUDnrVtgfxXdQ== Received: from johan by xi with local (Exim 4.93.0.4) (envelope-from ) id 1lVt1Y-0000Ck-E3; Mon, 12 Apr 2021 11:38:28 +0200 From: Johan Hovold To: Johan Hovold Cc: linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH 2/4] USB: serial: io_ti: document reason for drain delay Date: Mon, 12 Apr 2021 11:38:13 +0200 Message-Id: <20210412093815.736-3-johan@kernel.org> X-Mailer: git-send-email 2.26.3 In-Reply-To: <20210412093815.736-1-johan@kernel.org> References: <20210412093815.736-1-johan@kernel.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org Document that the device line-status register doesn't tell when the transmitter shift register has emptied and that this is why the one-character drain delay is needed. Signed-off-by: Johan Hovold --- drivers/usb/serial/io_ti.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/usb/serial/io_ti.c b/drivers/usb/serial/io_ti.c index 75325c2b295e..17720670e06c 100644 --- a/drivers/usb/serial/io_ti.c +++ b/drivers/usb/serial/io_ti.c @@ -2590,6 +2590,10 @@ static int edge_port_probe(struct usb_serial_port *port) if (ret) goto err; + /* + * The LSR does not tell when the transmitter shift register has + * emptied so add a one-character drain delay. + */ port->port.drain_delay = 1; return 0;