linux-kernel - [PATCH v2 1/2] serial: 8250_dw: handle clock enable errors in runtime

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Message-ID: <20251104145433.2316165-2-a.shimko.dev@gmail.com>
Date: Tue,  4 Nov 2025 17:54:25 +0300
From: Artem Shimko <a.shimko.dev@...il.com>
To: ilpo.jarvinen@...ux.intel.com,
	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Jiri Slaby <jirislaby@...nel.org>
Cc: Artem Shimko <a.shimko.dev@...il.com>,
	linux-kernel@...r.kernel.org,
	linux-serial@...r.kernel.org
Subject: [PATCH v2 1/2] serial: 8250_dw: handle clock enable errors in runtime_resume

Add error checking for clk_prepare_enable() calls in
dw8250_runtime_resume(). Currently if either clock fails to enable,
the function returns success while leaving clocks in inconsistent state.

This change implements comprehensive error handling by checking the return
values of both clk_prepare_enable() calls. If the second clock enable
operation fails after the first clock has already been successfully
enabled, the code now properly cleans up by disabling and unpreparing
the first clock before returning. The error code is then propagated to
the caller, ensuring that clock enable failures are properly reported
rather than being silently ignored.

Signed-off-by: Artem Shimko <a.shimko.dev@...il.com>
---
 drivers/tty/serial/8250/8250_dw.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/tty/serial/8250/8250_dw.c b/drivers/tty/serial/8250/8250_dw.c
index 710ae4d40aec..0ff500965c10 100644
--- a/drivers/tty/serial/8250/8250_dw.c
+++ b/drivers/tty/serial/8250/8250_dw.c
@@ -741,11 +741,18 @@ static int dw8250_runtime_suspend(struct device *dev)

 static int dw8250_runtime_resume(struct device *dev)
 {
+	int ret;
 	struct dw8250_data *data = dev_get_drvdata(dev);

-	clk_prepare_enable(data->pclk);
+	ret = clk_prepare_enable(data->pclk);
+	if (ret)
+		return ret;

-	clk_prepare_enable(data->clk);
+	ret = clk_prepare_enable(data->clk);
+	if (ret) {
+		clk_disable_unprepare(data->pclk);
+		return ret;
+	}

 	return 0;
 }
-- 
2.43.0