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 7AAF3C433EF for ; Mon, 7 Mar 2022 09:35:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235465AbiCGJg0 (ORCPT ); Mon, 7 Mar 2022 04:36:26 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54400 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237545AbiCGJgM (ORCPT ); Mon, 7 Mar 2022 04:36:12 -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 E78BE6C1CA; Mon, 7 Mar 2022 01:31:22 -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 936A2CE0E97; Mon, 7 Mar 2022 09:31:03 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E8BF0C340F3; Mon, 7 Mar 2022 09:31:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1646645461; bh=1Bl2ar5Dxwk0F+m00os++GOOiJ+ZMgRAWAFAKEAioZk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=gy3DmEOKZlboRrBzx5NMA8WE+ijEPZlR/+WWaeosz07V23Hpp8/6GOpC7+cdk6JQg 3nWtTKIRecHGhgKq1xAoLrvQoPhJuDEX9wNH1fdDzp0y3sEZ3e7cPwyegK0wG43N+z 97+XczsnKr4UUte/gg/kgMIz8WrYGmoRLuw9P3rs= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Valentin Caron , Sasha Levin Subject: [PATCH 5.10 021/105] serial: stm32: prevent TDR register overwrite when sending x_char Date: Mon, 7 Mar 2022 10:18:24 +0100 Message-Id: <20220307091644.780354581@linuxfoundation.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220307091644.179885033@linuxfoundation.org> References: <20220307091644.179885033@linuxfoundation.org> User-Agent: quilt/0.66 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: Valentin Caron [ Upstream commit d3d079bde07e1b7deaeb57506dc0b86010121d17 ] When sending x_char in stm32_usart_transmit_chars(), driver can overwrite the value of TDR register by the value of x_char. If this happens, the previous value that was present in TDR register will not be sent through uart. This code checks if the previous value in TDR register is sent before writing the x_char value into register. Fixes: 48a6092fb41f ("serial: stm32-usart: Add STM32 USART Driver") Cc: stable Signed-off-by: Valentin Caron Link: https://lore.kernel.org/r/20220111164441.6178-2-valentin.caron@foss.st.com Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin --- drivers/tty/serial/stm32-usart.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c index 0eadf0547175c..6afae051ba8d1 100644 --- a/drivers/tty/serial/stm32-usart.c +++ b/drivers/tty/serial/stm32-usart.c @@ -420,10 +420,22 @@ static void stm32_usart_transmit_chars(struct uart_port *port) struct stm32_port *stm32_port = to_stm32_port(port); const struct stm32_usart_offsets *ofs = &stm32_port->info->ofs; struct circ_buf *xmit = &port->state->xmit; + u32 isr; + int ret; if (port->x_char) { if (stm32_port->tx_dma_busy) stm32_usart_clr_bits(port, ofs->cr3, USART_CR3_DMAT); + + /* Check that TDR is empty before filling FIFO */ + ret = + readl_relaxed_poll_timeout_atomic(port->membase + ofs->isr, + isr, + (isr & USART_SR_TXE), + 10, 1000); + if (ret) + dev_warn(port->dev, "1 character may be erased\n"); + writel_relaxed(port->x_char, port->membase + ofs->tdr); port->x_char = 0; port->icount.tx++; -- 2.34.1