[PATCH] drm/stm/ltdc: Fix clock cleanup error handling

When clk_prepare_enable() fails for bus_clk or lvds_clk, the previously
prepared clocks are not cleaned up, leading to resource leaks.

In ltdc_resume():
- If bus_clk preparation fails, pixel_clk remains prepared
- If lvds_clk preparation fails, both pixel_clk and bus_clk remain prepared

In ltdc_load():
- If bus_clk preparation fails, pixel_clk remains prepared

Fix this by adding proper error handling to ensure all prepared clocks
are disabled and unprepared when a subsequent clock preparation fails.

Fixes: df61c776657f ("drm/stm: add sleep power management")
Fixes: d80667642b0f ("drm/stm: ltdc: support new hardware version for STM32MP25 SoC")
Fixes: b7243862f82a ("drm/stm: ltdc: handle lvds pixel clock")
Cc: [email protected]
Signed-off-by: Hongling Zeng <[email protected]>
---
Changes in v2:
- Use separate error labels in ltdc_load() so a failed bus clock is not
  passed to clk_disable_unprepare().
- Keep cleanup limited to clocks that were successfully prepared.
---
 drivers/gpu/drm/stm/ltdc.c | 20 ++++++++++++++------
 1 file changed, 14 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/stm/ltdc.c b/drivers/gpu/drm/stm/ltdc.c
index 8818dcf98da7..ac1c2f27563e 100644
--- a/drivers/gpu/drm/stm/ltdc.c
+++ b/drivers/gpu/drm/stm/ltdc.c
@@ -1908,16 +1908,25 @@ int ltdc_resume(struct drm_device *ddev)
 		ret = clk_prepare_enable(ldev->bus_clk);
 		if (ret) {
 			drm_err(ddev, "failed to enable bus clock (%d)\n", ret);
-			return ret;
+			goto err_pixel;
 		}
 	}
 
 	if (ldev->lvds_clk) {
 		ret = clk_prepare_enable(ldev->lvds_clk);
-		if (ret)
+		if (ret) {
 			drm_err(ddev, "failed to prepare lvds clock\n");
+			goto err_bus;
+		}
 	}
 
+	return 0;
+
+err_bus:
+	if (ldev->bus_clk)
+		clk_disable_unprepare(ldev->bus_clk);
+err_pixel:
+	clk_disable_unprepare(ldev->pixel_clk);
 	return ret;
 }
 
@@ -1963,7 +1972,7 @@ int ltdc_load(struct drm_device *ddev)
 		ret = clk_prepare_enable(ldev->bus_clk);
 		if (ret) {
 			drm_err(ddev, "Unable to prepare bus clock\n");
-			return ret;
+			goto err_pixel;
 		}
 	}
 
@@ -2093,11 +2102,10 @@ int ltdc_load(struct drm_device *ddev)
 
 	return 0;
 err:
-	clk_disable_unprepare(ldev->pixel_clk);
-
 	if (ldev->bus_clk)
 		clk_disable_unprepare(ldev->bus_clk);
-
+err_pixel:
+	clk_disable_unprepare(ldev->pixel_clk);
 	return ret;
 }
 
-- 
2.25.1