During probe, this driver is registering two platform devices: one
for the HDMI Codec driver and one for the DisplayPort PHY driver.

In the probe function, none of the error cases are unregistering
any of the two platform devices and this may cause registration
of multiple instances of those in case this driver returns one or
more probe deferral(s) in the "wrong" spots.

In order to fix this, add devm actions to unregister those and
remove the manual calls to platform_device_unregister in the
mtk_dp_remove() function, as those would otherwise be redundant.

Fixes: e71a8ebbe086 ("drm/mediatek: dp: Audio support for MT8195")
Fixes: caf2ae486742 ("drm/mediatek: dp: Add support for embedded DisplayPort aux-bus")
Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
---
 drivers/gpu/drm/mediatek/mtk_dp.c | 30 ++++++++++++++++++++++++++----
 1 file changed, 26 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/mediatek/mtk_dp.c b/drivers/gpu/drm/mediatek/mtk_dp.c
index 3d4648d2e15f..3eb685a46d99 100644
--- a/drivers/gpu/drm/mediatek/mtk_dp.c
+++ b/drivers/gpu/drm/mediatek/mtk_dp.c
@@ -2648,6 +2648,13 @@ static const struct hdmi_codec_ops mtk_dp_audio_codec_ops = {
 	.hook_plugged_cb = mtk_dp_audio_hook_plugged_cb,
 };
 
+static void mtk_dp_unregister_pdevs(void *data)
+{
+	struct platform_device *ext_pdev = data;
+
+	platform_device_unregister(ext_pdev);
+}
+
 static int mtk_dp_register_audio_driver(struct device *dev)
 {
 	struct mtk_dp *mtk_dp = dev_get_drvdata(dev);
@@ -2658,18 +2665,29 @@ static int mtk_dp_register_audio_driver(struct device *dev)
 		.data = mtk_dp,
 		.no_capture_mute = 1,
 	};
+	int ret;
 
 	mtk_dp->audio_pdev = platform_device_register_data(dev,
 							   HDMI_CODEC_DRV_NAME,
 							   PLATFORM_DEVID_AUTO,
 							   &codec_data,
 							   sizeof(codec_data));
-	return PTR_ERR_OR_ZERO(mtk_dp->audio_pdev);
+	if (IS_ERR(mtk_dp->audio_pdev))
+		return PTR_ERR(mtk_dp->audio_pdev);
+
+	ret = devm_add_action_or_reset(dev, mtk_dp_unregister_pdevs, mtk_dp->phy_dev);
+	if (ret) {
+		platform_device_unregister(mtk_dp->audio_pdev);
+		return dev_err_probe(dev, ret,
+				     "Failed to add codec unregister devm action");
+	}
+	return 0;
 }
 
 static int mtk_dp_register_phy(struct mtk_dp *mtk_dp)
 {
 	struct device *dev = mtk_dp->dev;
+	int ret;
 
 	mtk_dp->phy_dev = platform_device_register_data(dev, "mediatek-dp-phy",
 							PLATFORM_DEVID_AUTO,
@@ -2679,6 +2697,13 @@ static int mtk_dp_register_phy(struct mtk_dp *mtk_dp)
 		return dev_err_probe(dev, PTR_ERR(mtk_dp->phy_dev),
 				     "Failed to create device mediatek-dp-phy\n");
 
+	ret = devm_add_action_or_reset(dev, mtk_dp_unregister_pdevs, mtk_dp->phy_dev);
+	if (ret) {
+		platform_device_unregister(mtk_dp->phy_dev);
+		return dev_err_probe(dev, ret,
+				     "Failed to add phy unregister devm action");
+	}
+
 	mtk_dp_get_calibration_data(mtk_dp);
 
 	mtk_dp->phy = devm_phy_get(&mtk_dp->phy_dev->dev, "dp");
@@ -2848,9 +2873,6 @@ static void mtk_dp_remove(struct platform_device *pdev)
 	pm_runtime_disable(&pdev->dev);
 	if (mtk_dp->data->bridge_type != DRM_MODE_CONNECTOR_eDP)
 		del_timer_sync(&mtk_dp->debounce_timer);
-	platform_device_unregister(mtk_dp->phy_dev);
-	if (mtk_dp->audio_pdev)
-		platform_device_unregister(mtk_dp->audio_pdev);
 }
 
 #ifdef CONFIG_PM_SLEEP
-- 
2.48.1