linux-kernel - [PATCH] tty: serial: meson: Use devm_clk_get

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Date:   Wed, 24 Aug 2022 10:06:21 +0200
From:   Christophe JAILLET <christophe.jaillet@...adoo.fr>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jirislaby@...nel.org>,
        Neil Armstrong <neil.armstrong@...aro.org>,
        Kevin Hilman <khilman@...libre.com>,
        Jerome Brunet <jbrunet@...libre.com>,
        Martin Blumenstingl <martin.blumenstingl@...glemail.com>
Cc:     linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org,
        Christophe JAILLET <christophe.jaillet@...adoo.fr>,
        linux-serial@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-amlogic@...ts.infradead.org
Subject: [PATCH] tty: serial: meson: Use devm_clk_get_enabled() helper

The devm_clk_get_enabled() helper:
   - calls devm_clk_get()
   - calls clk_prepare_enable() and registers what is needed in order to
     call clk_disable_unprepare() when needed, as a managed resource.

This simplifies the code, the error handling paths and avoid the need of
a dedicated function used with devm_add_action_or_reset().

That said, meson_uart_probe_clock() is now more or less the same as
devm_clk_get_enabled(), so use this function directly instead.

This also fixes an (unlikely) unchecked devm_add_action_or_reset() error.

Based on my test with allyesconfig, this reduces the .o size from:
   text	   data	    bss	    dec	    hex	filename
   16350	   5016	    128	  21494	   53f6	drivers/tty/serial/meson_uart.o
down to:
   15415	   4784	    128	  20327	   4f67	drivers/tty/serial/meson_uart.o

Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
---
devm_clk_get_enabled() is new and is part of 6.0-rc1

If the message "couldn't enable clk\n" is of any use, it could be added
in meson_uart_probe_clocks() with a dev_err_probe() call. It wouldn't be
exactly the same meaning, but at least something would be logged.
---
 drivers/tty/serial/meson_uart.c | 29 +++--------------------------
 1 file changed, 3 insertions(+), 26 deletions(-)

diff --git a/drivers/tty/serial/meson_uart.c b/drivers/tty/serial/meson_uart.c
index 6c8db19fd572..26de08bf181e 100644
--- a/drivers/tty/serial/meson_uart.c
+++ b/drivers/tty/serial/meson_uart.c
@@ -667,29 +667,6 @@ static struct uart_driver meson_uart_driver = {
 	.cons		= MESON_SERIAL_CONSOLE,
 };
 
-static inline struct clk *meson_uart_probe_clock(struct device *dev,
-						 const char *id)
-{
-	struct clk *clk = NULL;
-	int ret;
-
-	clk = devm_clk_get(dev, id);
-	if (IS_ERR(clk))
-		return clk;
-
-	ret = clk_prepare_enable(clk);
-	if (ret) {
-		dev_err(dev, "couldn't enable clk\n");
-		return ERR_PTR(ret);
-	}
-
-	devm_add_action_or_reset(dev,
-			(void(*)(void *))clk_disable_unprepare,
-			clk);
-
-	return clk;
-}
-
 static int meson_uart_probe_clocks(struct platform_device *pdev,
 				   struct uart_port *port)
 {
@@ -697,15 +674,15 @@ static int meson_uart_probe_clocks(struct platform_device *pdev,
 	struct clk *clk_pclk = NULL;
 	struct clk *clk_baud = NULL;
 
-	clk_pclk = meson_uart_probe_clock(&pdev->dev, "pclk");
+	clk_pclk = devm_clk_get_enabled(&pdev->dev, "pclk");
 	if (IS_ERR(clk_pclk))
 		return PTR_ERR(clk_pclk);
 
-	clk_xtal = meson_uart_probe_clock(&pdev->dev, "xtal");
+	clk_xtal = devm_clk_get_enabled(&pdev->dev, "xtal");
 	if (IS_ERR(clk_xtal))
 		return PTR_ERR(clk_xtal);
 
-	clk_baud = meson_uart_probe_clock(&pdev->dev, "baud");
+	clk_baud = devm_clk_get_enabled(&pdev->dev, "baud");
 	if (IS_ERR(clk_baud))
 		return PTR_ERR(clk_baud);
 
-- 
2.34.1