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 D0F7CC433F5 for ; Sun, 30 Jan 2022 14:45:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1355134AbiA3OpZ (ORCPT ); Sun, 30 Jan 2022 09:45:25 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58810 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1355132AbiA3OpM (ORCPT ); Sun, 30 Jan 2022 09:45:12 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D07A8C061758 for ; Sun, 30 Jan 2022 06:45:07 -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 dfw.source.kernel.org (Postfix) with ESMTPS id 70446611CD for ; Sun, 30 Jan 2022 14:45:07 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5F08AC340E4; Sun, 30 Jan 2022 14:45:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1643553906; bh=LTjZF5VwICV/jnA/dFqJjs18kdrTzMCwOTdJpP9x+o4=; h=Subject:To:Cc:From:Date:From; b=BiE9dYx0D1IVuNUtss8ogxEMXkZ7B8eAU7A0sKNkvbUUFtY6F1Zjac7BJAMFoJxyX nYOY/mjiOvTd4dxuIu6n8fOlwUonaM/fXZFQdANosCUJurtsX8bHgMcucl2kGXahVv D28yop6RtBGr1i52v7nmqf5ZcmYFl7o4rAfiXi0c= Subject: FAILED: patch "[PATCH] serial: stm32: prevent TDR register overwrite when sending" failed to apply to 5.4-stable tree To: valentin.caron@foss.st.com, gregkh@linuxfoundation.org, stable@vger.kernel.org Cc: From: Date: Sun, 30 Jan 2022 15:44:50 +0100 Message-ID: <1643553890188161@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 5.4-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++;