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 7B1E3C88CB9 for ; Thu, 24 Aug 2023 17:19:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242540AbjHXRTG (ORCPT ); Thu, 24 Aug 2023 13:19:06 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35936 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242851AbjHXRSy (ORCPT ); Thu, 24 Aug 2023 13:18:54 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 22B0019BA for ; Thu, 24 Aug 2023 10:18:53 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id B4D06674CE for ; Thu, 24 Aug 2023 17:18:52 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C8F87C433C8; Thu, 24 Aug 2023 17:18:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1692897532; bh=Loy9pJrvJHpaZ0s5DjlXnTgzYWMEm6nGQXGvqr8Jfx4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=guIDmn+dvcjXFW2IhaZlQDC+14FfwaEqTHflBI6lbqtUp4eMBnbbNXYUr8RZPuPrn S+0KK+0mHkcbCELnYIURwpLCmCbZtu50PUz2HdDBgqPrfVH3qEzeWwCJ6+bnidyE3z QZR9OX1r1HKJGL+pCnJJ2TECJXAtpcBX8VuHiHxU= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, stable , Sherry Sun Subject: [PATCH 5.10 073/135] tty: serial: fsl_lpuart: Clear the error flags by writing 1 for lpuart32 platforms Date: Thu, 24 Aug 2023 19:09:05 +0200 Message-ID: <20230824170620.379199251@linuxfoundation.org> X-Mailer: git-send-email 2.42.0 In-Reply-To: <20230824170617.074557800@linuxfoundation.org> References: <20230824170617.074557800@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org 5.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Sherry Sun commit 282069845af388b08d622ad192b831dcd0549c62 upstream. Do not read the data register to clear the error flags for lpuart32 platforms, the additional read may cause the receive FIFO underflow since the DMA has already read the data register. Actually all lpuart32 platforms support write 1 to clear those error bits, let's use this method to better clear the error flags. Fixes: 42b68768e51b ("serial: fsl_lpuart: DMA support for 32-bit variant") Cc: stable Signed-off-by: Sherry Sun Link: https://lore.kernel.org/r/20230801022304.24251-1-sherry.sun@nxp.com Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/fsl_lpuart.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/drivers/tty/serial/fsl_lpuart.c +++ b/drivers/tty/serial/fsl_lpuart.c @@ -1062,8 +1062,8 @@ static void lpuart_copy_rx_to_tty(struct unsigned long sr = lpuart32_read(&sport->port, UARTSTAT); if (sr & (UARTSTAT_PE | UARTSTAT_FE)) { - /* Read DR to clear the error flags */ - lpuart32_read(&sport->port, UARTDATA); + /* Clear the error flags */ + lpuart32_write(&sport->port, sr, UARTSTAT); if (sr & UARTSTAT_PE) sport->port.icount.parity++;