From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E9104C43217 for ; Wed, 23 Nov 2022 08:55:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236717AbiKWIzB (ORCPT ); Wed, 23 Nov 2022 03:55:01 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58314 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236727AbiKWIyz (ORCPT ); Wed, 23 Nov 2022 03:54:55 -0500 Received: from sin.source.kernel.org (sin.source.kernel.org [IPv6:2604:1380:40e1:4800::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 11069EA114 for ; Wed, 23 Nov 2022 00:54:54 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by sin.source.kernel.org (Postfix) with ESMTPS id CC3D9CE2034 for ; Wed, 23 Nov 2022 08:54:51 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6CC41C433C1; Wed, 23 Nov 2022 08:54:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1669193690; bh=k5396sCD0FQY43oH0pcZGzw6uRXDPi91y2vkdhbN8a0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=u20Fn4rh1NV8Srr/5Umi5QM6hLYje3tkr7UYYpcnYpofQJYF6Fi8y8HwBpYj9iTeT NhidMKVJtaK/mlxvFDgkemQUPrxxEGHrQ31RN/QAY2g5OMOuX3DtDaK5adCqQEhlYC gjISJOn4QkqHJEFQ06vapIwZS9rEe6rst5zAI2MY= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, =?UTF-8?q?Ilpo=20J=C3=A4rvinen?= , Matthias Schiffer , Sasha Levin Subject: [PATCH 4.9 34/76] serial: 8250_omap: remove wait loop from Errata i202 workaround Date: Wed, 23 Nov 2022 09:50:33 +0100 Message-Id: <20221123084547.851390697@linuxfoundation.org> X-Mailer: git-send-email 2.38.1 In-Reply-To: <20221123084546.742331901@linuxfoundation.org> References: <20221123084546.742331901@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Matthias Schiffer [ Upstream commit e828e56684d61b17317e0cfdef83791fa61cb76b ] We were occasionally seeing the "Errata i202: timedout" on an AM335x board when repeatedly opening and closing a UART connected to an active sender. As new input may arrive at any time, it is possible to miss the "RX FIFO empty" condition, forcing the loop to wait until it times out. Nothing in the i202 Advisory states that such a wait is even necessary; other FIFO clear functions like serial8250_clear_fifos() do not wait either. For this reason, it seems safe to remove the wait, fixing the mentioned issue. Fixes: 61929cf0169d ("tty: serial: Add 8250-core based omap driver") Reviewed-by: Ilpo Järvinen Signed-off-by: Matthias Schiffer Link: https://lore.kernel.org/r/20221013112339.2540767-1-matthias.schiffer@ew.tq-group.com Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin --- drivers/tty/serial/8250/8250_omap.c | 17 ----------------- 1 file changed, 17 deletions(-) diff --git a/drivers/tty/serial/8250/8250_omap.c b/drivers/tty/serial/8250/8250_omap.c index c551407bee07..cecc266b3640 100644 --- a/drivers/tty/serial/8250/8250_omap.c +++ b/drivers/tty/serial/8250/8250_omap.c @@ -160,27 +160,10 @@ static void omap8250_set_mctrl(struct uart_port *port, unsigned int mctrl) static void omap_8250_mdr1_errataset(struct uart_8250_port *up, struct omap8250_priv *priv) { - u8 timeout = 255; - serial_out(up, UART_OMAP_MDR1, priv->mdr1); udelay(2); serial_out(up, UART_FCR, up->fcr | UART_FCR_CLEAR_XMIT | UART_FCR_CLEAR_RCVR); - /* - * Wait for FIFO to empty: when empty, RX_FIFO_E bit is 0 and - * TX_FIFO_E bit is 1. - */ - while (UART_LSR_THRE != (serial_in(up, UART_LSR) & - (UART_LSR_THRE | UART_LSR_DR))) { - timeout--; - if (!timeout) { - /* Should *never* happen. we warn and carry on */ - dev_crit(up->port.dev, "Errata i202: timedout %x\n", - serial_in(up, UART_LSR)); - break; - } - udelay(1); - } } static void omap_8250_get_divisor(struct uart_port *port, unsigned int baud, -- 2.35.1