drm/mediatek: mtk_hdmi: Unregister audio platform device on failure

[ Upstream commit 0be123c ]

The probe function of this driver may fail after registering the
audio platform device: in that case, the state is not getting
cleaned up, leaving this device registered.

Adding up to the mix, should the probe function of this driver
return a probe deferral for N times, we're registering up to N
audio platform devices and, again, never freeing them up.

To fix this, add a pointer to the audio platform device in the
mtk_hdmi structure, and add a devm action to unregister it upon
driver removal or probe failure.

Fixes: 8f83f26 ("drm/mediatek: Add HDMI support")
Reviewed-by: CK Hu <ck.hu@mediatek.com>
Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://patchwork.kernel.org/project/linux-mediatek/patch/20250217154836.108895-18-angelogioacchino.delregno@collabora.com/
Signed-off-by: Chun-Kuang Hu <chunkuang.hu@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

drivers/gpu/drm/mediatek/mtk_hdmi.c

@@ -173,6 +173,7 @@ struct mtk_hdmi {
 	unsigned int sys_offset;
 	void __iomem *regs;
 	enum hdmi_colorspace csp;
+	struct platform_device *audio_pdev;
 	struct hdmi_audio_param aud_param;
 	bool audio_enable;
 	bool powered;
@@ -1666,6 +1667,11 @@ static const struct hdmi_codec_ops mtk_hdmi_audio_codec_ops = {
 	.no_capture_mute = 1,
 };
 
+static void mtk_hdmi_unregister_audio_driver(void *data)
+{
+	platform_device_unregister(data);
+}
+
 static int mtk_hdmi_register_audio_driver(struct device *dev)
 {
 	struct mtk_hdmi *hdmi = dev_get_drvdata(dev);
@@ -1675,13 +1681,20 @@ static int mtk_hdmi_register_audio_driver(struct device *dev)
 		.i2s = 1,
 		.data = hdmi,
 	};
-	struct platform_device *pdev;
+	int ret;
 
-	pdev = platform_device_register_data(dev, HDMI_CODEC_DRV_NAME,
-					     PLATFORM_DEVID_AUTO, &codec_data,
-					     sizeof(codec_data));
-	if (IS_ERR(pdev))
-		return PTR_ERR(pdev);
+	hdmi->audio_pdev = platform_device_register_data(dev,
+							 HDMI_CODEC_DRV_NAME,
+							 PLATFORM_DEVID_AUTO,
+							 &codec_data,
+							 sizeof(codec_data));
+	if (IS_ERR(hdmi->audio_pdev))
+		return PTR_ERR(hdmi->audio_pdev);
+
+	ret = devm_add_action_or_reset(dev, mtk_hdmi_unregister_audio_driver,
+				       hdmi->audio_pdev);
+	if (ret)
+		return ret;
 
 	DRM_INFO("%s driver bound to HDMI\n", HDMI_CODEC_DRV_NAME);
 	return 0;