From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3DD3A20F8F for ; Fri, 21 Jul 2023 19:23:52 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B5DF3C433C7; Fri, 21 Jul 2023 19:23:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1689967432; bh=BAgm6WRvlXtxDvOALlBp+GypJiNiT5K1hygsApGbHYo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=wmi696toEkkMU31970YxMv8KG1mU85YEwpDYv5pqfsqDrr/3MsOOM6IgI/2lkJPTt sVI4qj9zzFUdWw5bjR5/n48dE9x548PUG8OKvY7QysjcMo66HLL0s6yJoC3KXfs7Bk BRvU0s+bW2iv0Agb/bc41IAW0X60cmOVJStduAQE= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Martin Fuzzey , =?UTF-8?q?Ilpo=20J=C3=A4rvinen?= Subject: [PATCH 6.1 160/223] tty: serial: imx: fix rs485 rx after tx Date: Fri, 21 Jul 2023 18:06:53 +0200 Message-ID: <20230721160527.700771637@linuxfoundation.org> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20230721160520.865493356@linuxfoundation.org> References: <20230721160520.865493356@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Martin Fuzzey commit 639949a7031e04c59ec91614eceb9543e9120f43 upstream. Since commit 79d0224f6bf2 ("tty: serial: imx: Handle RS485 DE signal active high") RS485 reception no longer works after a transmission. The following scenario shows the problem: 1) Open a port in RS485 mode 2) Receive data from remote (OK) 3) Transmit data to remote (OK) 4) Receive data from remote (Nothing received) In RS485 mode, imx_uart_start_tx() calls imx_uart_stop_rx() and, when the transmission is complete, imx_uart_stop_tx() calls imx_uart_start_rx(). Since the above commit imx_uart_stop_rx() now sets the loopback bit but imx_uart_start_rx() does not clear it causing the hardware to remain in loopback mode and not receive external data. Fix this by moving the existing loopback disable code to a helper function and calling it from imx_uart_start_rx() too. Fixes: 79d0224f6bf2 ("tty: serial: imx: Handle RS485 DE signal active high") Cc: stable@vger.kernel.org Signed-off-by: Martin Fuzzey Reviewed-by: Ilpo Järvinen Link: https://lore.kernel.org/r/20230616104838.2729694-1-martin.fuzzey@flowbird.group Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/imx.c | 18 +++++++++++++----- 1 file changed, 13 insertions(+), 5 deletions(-) --- a/drivers/tty/serial/imx.c +++ b/drivers/tty/serial/imx.c @@ -397,6 +397,16 @@ static void start_hrtimer_ms(struct hrti hrtimer_start(hrt, ms_to_ktime(msec), HRTIMER_MODE_REL); } +static void imx_uart_disable_loopback_rs485(struct imx_port *sport) +{ + unsigned int uts; + + /* See SER_RS485_ENABLED/UTS_LOOP comment in imx_uart_probe() */ + uts = imx_uart_readl(sport, imx_uart_uts_reg(sport)); + uts &= ~UTS_LOOP; + imx_uart_writel(sport, uts, imx_uart_uts_reg(sport)); +} + /* called with port.lock taken and irqs off */ static void imx_uart_start_rx(struct uart_port *port) { @@ -418,6 +428,7 @@ static void imx_uart_start_rx(struct uar /* Write UCR2 first as it includes RXEN */ imx_uart_writel(sport, ucr2, UCR2); imx_uart_writel(sport, ucr1, UCR1); + imx_uart_disable_loopback_rs485(sport); } /* called with port.lock taken and irqs off */ @@ -1404,7 +1415,7 @@ static int imx_uart_startup(struct uart_ int retval, i; unsigned long flags; int dma_is_inited = 0; - u32 ucr1, ucr2, ucr3, ucr4, uts; + u32 ucr1, ucr2, ucr3, ucr4; retval = clk_prepare_enable(sport->clk_per); if (retval) @@ -1509,10 +1520,7 @@ static int imx_uart_startup(struct uart_ imx_uart_writel(sport, ucr2, UCR2); } - /* See SER_RS485_ENABLED/UTS_LOOP comment in imx_uart_probe() */ - uts = imx_uart_readl(sport, imx_uart_uts_reg(sport)); - uts &= ~UTS_LOOP; - imx_uart_writel(sport, uts, imx_uart_uts_reg(sport)); + imx_uart_disable_loopback_rs485(sport); spin_unlock_irqrestore(&sport->port.lock, flags);