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| author | Marek Vasut <marek.vasut+renesas@mailbox.org> | 2026-02-06 15:57:53 +0300 |
|---|---|---|
| committer | Luca Ceresoli <luca.ceresoli@bootlin.com> | 2026-03-03 11:11:14 +0300 |
| commit | b8eb97ead862de7a321dd55a901542a372f8f1cd (patch) | |
| tree | ca8fbdf5c2df1ec3e9b1dfb401dd60e034121763 | |
| parent | abdcd4c3586dee8c190ac932cb544036b0c937b9 (diff) | |
| download | linux-b8eb97ead862de7a321dd55a901542a372f8f1cd.tar.xz | |
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 <luca.ceresoli@bootlin.com>
Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>
Link: https://patch.msgid.link/20260206125801.78705-1-marek.vasut+renesas@mailbox.org
Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
| -rw-r--r-- | drivers/gpu/drm/bridge/waveshare-dsi.c | 7 |
1 files changed, 1 insertions, 6 deletions
diff --git a/drivers/gpu/drm/bridge/waveshare-dsi.c b/drivers/gpu/drm/bridge/waveshare-dsi.c index 43f4e7412d72..9254446f5495 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[] = { |