[PATCH v2] gpio: omap: handle debounce clock preparation failure

[Jiawen Liu]

omap_gpio_probe() ignores the return value of clk_prepare() for the
debounce clock. If preparation fails, the driver still treats debounce as
available and may use or unprepare a clock that was not prepared.

Use devm_clk_get_prepared() and disable debounce if the clock cannot be
obtained or prepared. This keeps the existing behavior for clock lookup
failures. Remove both manual clk_unprepare() calls because the managed
clock is released on probe failure and device removal.

An earlier managed-clock conversion was dropped after a reported boot
failure. A follow-up removing the two manual unprepare calls was reported
to restore boot. This change also removes those calls.
Built gpio-omap.o with ARM multi_v7_defconfig and Clang 19; the current
patch has not been tested on OMAP hardware.

The original report was generated using BMC-Agent; source review and
maintainer feedback informed this revision.

Fixes: 5d9452e7c52a ("gpio: omap: fix clk_prepare/unprepare usage")
Suggested-by: Andreas Kemnade <andreas@xxxxxxxxxxxx>
Link: https://lore.kernel.org/r/tencent_B4F504456790E8BA3C4EAB80F4BFB6954E08@xxxxxx
Link: https://lkml.rescloud.iu.edu/hypermail/linux/kernel/2412.2/00414.html
Signed-off-by: Jiawen Liu <1298662399@xxxxxx>
---
Changes in v2:
- Use devm_clk_get_prepared() and remove both manual unprepare calls.
- Disable debounce on prepare failure, retaining clock-get failure behavior.
- Add the Fixes tag and describe the earlier managed-clock attempt.

Built with ARCH=arm, LLVM=-19, multi_v7_defconfig, W=1 and
CONFIG_GPIO_OMAP=y. No OMAP hardware test or current reproducer is available.

 drivers/gpio/gpio-omap.c | 10 ++--------
 1 file changed, 2 insertions(+), 8 deletions(-)

diff --git a/drivers/gpio/gpio-omap.c b/drivers/gpio/gpio-omap.c
index a9734b2a1..314bbb48e 100644
--- a/drivers/gpio/gpio-omap.c
+++ b/drivers/gpio/gpio-omap.c
@@ -1446,13 +1446,11 @@ static int omap_gpio_probe(struct platform_device *pdev)
 	}
 
 	if (bank->dbck_flag) {
-		bank->dbck = devm_clk_get(dev, "dbclk");
+		bank->dbck = devm_clk_get_prepared(dev, "dbclk");
 		if (IS_ERR(bank->dbck)) {
 			dev_err(dev,
-				"Could not get gpio dbck. Disable debounce\n");
+				"Could not get or prepare gpio dbck. Disable debounce\n");
 			bank->dbck_flag = false;
-		} else {
-			clk_prepare(bank->dbck);
 		}
 	}
 
@@ -1470,8 +1468,6 @@ static int omap_gpio_probe(struct platform_device *pdev)
 	if (ret) {
 		pm_runtime_put_sync(dev);
 		pm_runtime_disable(dev);
-		if (bank->dbck_flag)
-			clk_unprepare(bank->dbck);
 		return ret;
 	}
 
@@ -1492,8 +1488,6 @@ static void omap_gpio_remove(struct platform_device *pdev)
 	cpu_pm_unregister_notifier(&bank->nb);
 	gpiochip_remove(&bank->chip);
 	pm_runtime_disable(&pdev->dev);
-	if (bank->dbck_flag)
-		clk_unprepare(bank->dbck);
 }
 
 static int omap_gpio_runtime_suspend(struct device *dev)
-- 
2.34.1