drm/bridge: imx8mp-hdmi-tx-connector-fixup: show a warning when adding the overlay

Describing the HDMI connector in device tree is recommended. While the
overlay insertion is a workaround to avoid breaking existing devices, every
dts should be improved by adding a connector description.

Add a warning to make users aware as far as possible.

As a warning line cannot hold all the relevant info, add a detailed comment
in the code so it easy to find when the warning is seen.

Reviewed-by: Liu Ying <victor.liu@nxp.com>
Link: https://patch.msgid.link/20260407-drm-lcdif-dbanc-v4-9-247a16e61ef9@bootlin.com
Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>

diff --git a/drivers/gpu/drm/bridge/imx/imx8mp-hdmi-tx-connector-fixup.c b/drivers/gpu/drm/bridge/imx/imx8mp-hdmi-tx-connector-fixup.c
index dc1736bfc3ac26fe9cf947190699f1ba6fd8b7a9..aaac27d00590cdecb390fc52dd2c5d64a52dbe2e 100644 (file)
--- a/drivers/gpu/drm/bridge/imx/imx8mp-hdmi-tx-connector-fixup.c
+++ b/drivers/gpu/drm/bridge/imx/imx8mp-hdmi-tx-connector-fixup.c
@@ -44,6 +44,23 @@ static int __init imx8mp_hdmi_tx_connector_fixup_init(void)
        if (endpoint)
                return 0;
 
+       /*
+        * Boards with an HDMI connector should describe it in a device
+        * tree node with compatible = "hdmi-connector".
+        *
+        * If you see this warning, it means such a node was not found and
+        * a fallback one is added using a device tree overlay. Please add
+        * one in your device tree, also describing the exact connector
+        * type (the added overlay assumes Type A as a fallback, but it
+        * might be wrong).
+        *
+        * This node is necessary for modern DRM, where bridge drivers do
+        * not create a connector (see the DRM_BRIDGE_ATTACH_NO_CONNECTOR
+        * flag). See https://docs.kernel.org/gpu/drm-kms-helpers.html for
+        * more info.
+        */
+       pr_warn("Please add a hdmi-connector DT node for imx8mp-hdmi-tx.\n");
+
        dtbo_start = __dtbo_imx8mp_hdmi_tx_connector_fixup_begin;
        dtbo_size = __dtbo_imx8mp_hdmi_tx_connector_fixup_end -
                    __dtbo_imx8mp_hdmi_tx_connector_fixup_begin;