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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Fugang Duan <fugang.duan@nxp.com>,
        Sherry Sun <sherry.sun@nxp.com>,
        =?UTF-8?q?Ilpo=20J=C3=A4rvinen?= <ilpo.jarvinen@linux.intel.com>,
        Lukas Wunner <lukas@wunner.de>
Subject: [PATCH 5.15 118/148] serial: fsl_lpuart: Reset prior to registration
Date:   Mon, 26 Sep 2022 12:12:32 +0200
Message-Id: <20220926100800.561048554@linuxfoundation.org>
In-Reply-To: <20220926100756.074519146@linuxfoundation.org>
References: <20220926100756.074519146@linuxfoundation.org>
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From: Lukas Wunner <lukas@wunner.de>

commit 60f361722ad2ae5ee667d0b0545d40c42f754daf upstream.

Since commit bd5305dcabbc ("tty: serial: fsl_lpuart: do software reset
for imx7ulp and imx8qxp"), certain i.MX UARTs are reset after they've
already been registered.  Register state may thus be clobbered after
user space has begun to open and access the UART.

Avoid by performing the reset prior to registration.

Fixes: bd5305dcabbc ("tty: serial: fsl_lpuart: do software reset for imx7ulp and imx8qxp")
Cc: stable@vger.kernel.org # v5.15+
Cc: Fugang Duan <fugang.duan@nxp.com>
Cc: Sherry Sun <sherry.sun@nxp.com>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Link: https://lore.kernel.org/r/72fb646c1b0b11c989850c55f52f9ff343d1b2fa.1662884345.git.lukas@wunner.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/tty/serial/fsl_lpuart.c |    9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

--- a/drivers/tty/serial/fsl_lpuart.c
+++ b/drivers/tty/serial/fsl_lpuart.c
@@ -2726,14 +2726,15 @@ static int lpuart_probe(struct platform_
 		lpuart_reg.cons = LPUART_CONSOLE;
 		handler = lpuart_int;
 	}
-	ret = uart_add_one_port(&lpuart_reg, &sport->port);
-	if (ret)
-		goto failed_attach_port;
 
 	ret = lpuart_global_reset(sport);
 	if (ret)
 		goto failed_reset;
 
+	ret = uart_add_one_port(&lpuart_reg, &sport->port);
+	if (ret)
+		goto failed_attach_port;
+
 	ret = uart_get_rs485_mode(&sport->port);
 	if (ret)
 		goto failed_get_rs485;
@@ -2756,9 +2757,9 @@ static int lpuart_probe(struct platform_
 
 failed_irq_request:
 failed_get_rs485:
-failed_reset:
 	uart_remove_one_port(&lpuart_reg, &sport->port);
 failed_attach_port:
+failed_reset:
 	lpuart_disable_clks(sport);
 	return ret;
 }