linux-kernel - [PATCH v11 05/11] drm/mediatek: mtk_hdmi

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Message-Id: <20251023-mediatek-drm-hdmi-v2-v11-5-7873ec4a1edf@collabora.com>
Date: Thu, 23 Oct 2025 12:32:31 +0200
From: Louis-Alexis Eyraud <louisalexis.eyraud@...labora.com>
To: Chun-Kuang Hu <chunkuang.hu@...nel.org>, 
 Philipp Zabel <p.zabel@...gutronix.de>, David Airlie <airlied@...il.com>, 
 Simona Vetter <simona@...ll.ch>, Matthias Brugger <matthias.bgg@...il.com>, 
 AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>, 
 CK Hu <ck.hu@...iatek.com>
Cc: kernel@...labora.com, dri-devel@...ts.freedesktop.org, 
 linux-mediatek@...ts.infradead.org, linux-kernel@...r.kernel.org, 
 linux-arm-kernel@...ts.infradead.org, 
 Louis-Alexis Eyraud <louisalexis.eyraud@...labora.com>
Subject: [PATCH v11 05/11] drm/mediatek: mtk_hdmi_common: Make CEC support
 optional

From: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>

In preparation for adding a new driver for HDMIv2, for which CEC
is not strictly required, change the of_get_compatible_child()
failure error to -ENOTSUPP to be able to differentiate between
error conditions in mtk_hdmi_dt_parse_pdata().

In that case, if -ENOTSUPP is returned, this driver will print
an informative message saying that CEC support is unavailable,
as the devicetree node for that was not found, but after that,
function mtk_hdmi_dt_parse_pdata() will not return error to
the caller.

This will not change functionality of the mtk_hdmi (v1) driver
as that is still checking whether CEC is present and, if not,
will fail probing with an error saying that CEC is required
by HDMIv1.

Reviewed-by: CK Hu <ck.hu@...iatek.com>
Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
Signed-off-by: Louis-Alexis Eyraud <louisalexis.eyraud@...labora.com>
---
 drivers/gpu/drm/mediatek/mtk_hdmi_common.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/mediatek/mtk_hdmi_common.c b/drivers/gpu/drm/mediatek/mtk_hdmi_common.c
index f28e63716d7c2e2c6bdf5b28d24789bc926d2beb..989479fdfe40952762a1b63797bf602b520dcac5 100644
--- a/drivers/gpu/drm/mediatek/mtk_hdmi_common.c
+++ b/drivers/gpu/drm/mediatek/mtk_hdmi_common.c
@@ -253,12 +253,11 @@ static int mtk_hdmi_get_cec_dev(struct mtk_hdmi *hdmi, struct device *dev, struc
 	/* The CEC module handles HDMI hotplug detection */
 	cec_np = of_get_compatible_child(np->parent, "mediatek,mt8173-cec");
 	if (!cec_np)
-		return dev_err_probe(dev, -EINVAL, "Failed to find CEC node\n");
+		return dev_err_probe(dev, -ENOTSUPP, "Failed to find CEC node\n");
 
 	cec_pdev = of_find_device_by_node(cec_np);
 	if (!cec_pdev) {
-		dev_err(hdmi->dev, "Waiting for CEC device %pOF\n",
-			cec_np);
+		dev_err(hdmi->dev, "Waiting for CEC device %pOF\n", cec_np);
 		of_node_put(cec_np);
 		return -EPROBE_DEFER;
 	}
@@ -319,7 +318,9 @@ static int mtk_hdmi_dt_parse_pdata(struct mtk_hdmi *hdmi, struct platform_device
 		return dev_err_probe(dev, -EINVAL, "Failed to get ddc i2c adapter by node\n");
 
 	ret = mtk_hdmi_get_cec_dev(hdmi, dev, np);
-	if (ret)
+	if (ret == -ENOTSUPP)
+		dev_info(dev, "CEC support unavailable: node not found\n");
+	else if (ret)
 		return ret;
 
 	return 0;

-- 
2.51.0