linux-kernel - [PATCH 2/2] serial: imx: disable console clocks on unregister

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Message-Id: <20211014071053.568598-3-francesco.dolcini@toradex.com>
Date:   Thu, 14 Oct 2021 09:10:53 +0200
From:   Francesco Dolcini <francesco.dolcini@...adex.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jirislaby@...nel.org>,
        Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        Fabio Estevam <festevam@...il.com>,
        NXP Linux Team <linux-imx@....com>,
        Stefan Agner <stefan@...er.ch>
Cc:     Francesco Dolcini <francesco.dolcini@...adex.com>,
        linux-serial@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH 2/2] serial: imx: disable console clocks on unregister

During console setup imx_uart_console_setup() enables clocks, but they
are never disabled when the console is unregistered, this leads to
clk_prepare_enable() being called multiple times without a matching
clk_disable_unprepare() in case of unbind/bind.

Ensure that clock enable/disable are balanced adding
clk_disable_unprepare() in the console exit callback.

Signed-off-by: Francesco Dolcini <francesco.dolcini@...adex.com>
---
 drivers/tty/serial/imx.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index 51a9f9423b1a..90f82e6c54e4 100644
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -2124,12 +2124,24 @@ imx_uart_console_setup(struct console *co, char *options)
 	return retval;
 }
 
+static int
+imx_uart_console_exit(struct console *co)
+{
+	struct imx_port *sport = imx_uart_ports[co->index];
+
+	clk_disable_unprepare(sport->clk_per);
+	clk_disable_unprepare(sport->clk_ipg);
+
+	return 0;
+}
+
 static struct uart_driver imx_uart_uart_driver;
 static struct console imx_uart_console = {
 	.name		= DEV_NAME,
 	.write		= imx_uart_console_write,
 	.device		= uart_console_device,
 	.setup		= imx_uart_console_setup,
+	.exit		= imx_uart_console_exit,
 	.flags		= CON_PRINTBUFFER,
 	.index		= -1,
 	.data		= &imx_uart_uart_driver,
-- 
2.25.1