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 047DCC433EF for ; Sun, 30 Jan 2022 14:45:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1355142AbiA3OpO (ORCPT ); Sun, 30 Jan 2022 09:45:14 -0500 Received: from dfw.source.kernel.org ([139.178.84.217]:37904 "EHLO dfw.source.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1355149AbiA3OpC (ORCPT ); Sun, 30 Jan 2022 09:45:02 -0500 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 dfw.source.kernel.org (Postfix) with ESMTPS id 78662611CB for ; Sun, 30 Jan 2022 14:45:01 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 48D14C340E4; Sun, 30 Jan 2022 14:45:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1643553900; bh=3b8jqRuyqTGNo5J7fr/96feMg3ExQAMVIXQCi/EsG0E=; h=Subject:To:Cc:From:Date:From; b=hac3Q0nyPeFz/DvZJoTMYoN9gqmqugCQNi1m8YXzhjFPY/29jWBc36sP2EHb+Q0xV 1nuP3KeJpGuHzFIhsA9pYtwfyqIJwD1r5/pAypqkx2UsokzT2Yw1xatphwKQR1jc4P OyrCulA94Dh9v0nF12Mm2NNe3SEC0U15bkDIO/lY= Subject: FAILED: patch "[PATCH] serial: stm32: prevent TDR register overwrite when sending" failed to apply to 4.14-stable tree To: valentin.caron@foss.st.com, gregkh@linuxfoundation.org, stable@vger.kernel.org Cc: From: Date: Sun, 30 Jan 2022 15:44:47 +0100 Message-ID: <164355388725227@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org The patch below does not apply to the 4.14-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From d3d079bde07e1b7deaeb57506dc0b86010121d17 Mon Sep 17 00:00:00 2001 From: Valentin Caron Date: Tue, 11 Jan 2022 17:44:40 +0100 Subject: [PATCH] serial: stm32: prevent TDR register overwrite when sending x_char 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 diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c index 1f89ab0e49ac..c1b8828451c8 100644 --- a/drivers/tty/serial/stm32-usart.c +++ b/drivers/tty/serial/stm32-usart.c @@ -550,11 +550,23 @@ 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_usart_tx_dma_started(stm32_port) && stm32_usart_tx_dma_enabled(stm32_port)) 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++;