drm/panel-edp: add fat warning against adding new panel compatibles

Add a fat warning against adding new panel compatibles to the panel-edp
driver. All new users of the eDP panels are supposed to use the generic
"edp-panel" compatible device on the AUX bus. The remaining compatibles
are either used by the existing DT or were used previously and are
retained for backwards compatibility.

Suggested-by: Doug Anderson <dianders@chromium.org>
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Acked-by: Maxime Ripard <mripard@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20240614-edp-panel-drop-v4-1-4e0a112eec46@linaro.org
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>

diff --git a/drivers/gpu/drm/panel/panel-edp.c b/drivers/gpu/drm/panel/panel-edp.c
index 67ab6915d6e4dd6538c8b81fd6027736a1252a94..85edfd3d59f33a7414921dff4bc5f972920917fb 100644 (file)
--- a/drivers/gpu/drm/panel/panel-edp.c
+++ b/drivers/gpu/drm/panel/panel-edp.c
@@ -1762,7 +1762,24 @@ static const struct of_device_id platform_of_match[] = {
        {
                /* Must be first */
                .compatible = "edp-panel",
-       }, {
+       },
+       /*
+        * Do not add panels to the list below unless they cannot be handled by
+        * the generic edp-panel compatible.
+        *
+        * The only two valid reasons are:
+        * - Because of the panel issues (e.g. broken EDID or broken
+        *   identification).
+        * - Because the eDP drivers didn't wire up the AUX bus properly.
+        *   NOTE that, though this is a marginally valid reason,
+        *   some justification needs to be made for why the platform can't
+        *   wire up the AUX bus properly.
+        *
+        * In all other cases the platform should use the aux-bus and declare
+        * the panel using the 'edp-panel' compatible as a device on the AUX
+        * bus.
+        */
+       {
                .compatible = "auo,b101ean01",
                .data = &auo_b101ean01,
        }, {