From: Marek Vasut Date: Fri, 6 Feb 2026 12:57:53 +0000 (+0100) Subject: drm/bridge: waveshare-dsi: Register and attach our DSI device at probe X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=b8eb97ead862de7a321dd55a901542a372f8f1cd;p=thirdparty%2Fkernel%2Flinux.git drm/bridge: waveshare-dsi: Register and attach our DSI device at probe In order to avoid any probe ordering issue, the best practice is to move the secondary MIPI-DSI device registration and attachment to the MIPI-DSI host at probe time. Besides solving the probe ordering problems, this makes the bridge work with R-Car DU. The R-Car DU will attempt to locate the DSI host bridge in its own rcar_du_probe()->rcar_du_modeset_init()->rcar_du_encoder_init() by calling of_drm_find_bridge() which calls of_drm_find_and_get_bridge() and iterates over bridge_list to locate the DSI host bridge. However, unless the WS driver calls mipi_dsi_attach() in probe(), the DSI host bridge .attach callback rcar_mipi_dsi_host_attach() is not called and the DSI host bridge is not added into bridge_list. Therefore the of_drm_find_and_get_bridge() called from du_probe() will never find the DSI host bridge and probe will indefinitelly fail with -EPROBE_DEFER. The circular dependency here is, that if rcar_du_encoder_init() would manage to find the DSI host bridge, it would call the WS driver .attach callback ws_bridge_bridge_attach(), but this is too late and can never happen. This change avoids the circular dependency. Reviewed-by: Luca Ceresoli Signed-off-by: Marek Vasut Link: https://patch.msgid.link/20260206125801.78705-1-marek.vasut+renesas@mailbox.org Signed-off-by: Luca Ceresoli --- diff --git a/drivers/gpu/drm/bridge/waveshare-dsi.c b/drivers/gpu/drm/bridge/waveshare-dsi.c index 43f4e7412d722..9254446f54958 100644 --- a/drivers/gpu/drm/bridge/waveshare-dsi.c +++ b/drivers/gpu/drm/bridge/waveshare-dsi.c @@ -80,11 +80,6 @@ static int ws_bridge_bridge_attach(struct drm_bridge *bridge, enum drm_bridge_attach_flags flags) { struct ws_bridge *ws = bridge_to_ws_bridge(bridge); - int ret; - - ret = ws_bridge_attach_dsi(ws); - if (ret) - return ret; return drm_bridge_attach(encoder, ws->next_bridge, &ws->bridge, flags); @@ -179,7 +174,7 @@ static int ws_bridge_probe(struct i2c_client *i2c) ws->bridge.of_node = dev->of_node; devm_drm_bridge_add(dev, &ws->bridge); - return 0; + return ws_bridge_attach_dsi(ws); } static const struct of_device_id ws_bridge_of_ids[] = {