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Subject[PATCH 2/2] drm/bridge: tc358767: Fix link properties discovery
When a display controller driver uses DRM_BRIDGE_ATTACH_NO_CONNECTOR,
tc358767 will behave properly and skip the creation of the connector.

However, tc_get_display_props(), which is used to find out about the DP
monitor and link, is only called from two places: .atomic_enable() and
tc_connector_get_modes(). The latter is only used when tc358767 creates
its own connector, i.e. when DRM_BRIDGE_ATTACH_NO_CONNECTOR is _not_
set.

Thus, the driver never finds out the link properties before get_edid()
is called. With num_lanes of 0 and link_rate of 0 there are not many
valid modes...

Fix this by adding tc_connector_get_modes() call at the beginning of
get_edid(), so that we have up to date information before looking at the
modes.

Reported-by: Jan Kiszka <jan.kiszka@siemens.com>
Closes: https://lore.kernel.org/all/24282420-b4dd-45b3-bb1c-fc37fe4a8205@siemens.com/
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
---
drivers/gpu/drm/bridge/tc358767.c | 7 +++++++
1 file changed, 7 insertions(+)

diff --git a/drivers/gpu/drm/bridge/tc358767.c b/drivers/gpu/drm/bridge/tc358767.c
index 0affcefdeb1c..137a9f5e3cad 100644
--- a/drivers/gpu/drm/bridge/tc358767.c
+++ b/drivers/gpu/drm/bridge/tc358767.c
@@ -1579,6 +1579,13 @@ static struct edid *tc_get_edid(struct drm_bridge *bridge,
struct drm_connector *connector)
{
struct tc_data *tc = bridge_to_tc(bridge);
+ int ret;
+
+ ret = tc_get_display_props(tc);
+ if (ret < 0) {
+ dev_err(tc->dev, "failed to read display props: %d\n", ret);
+ return 0;
+ }

return drm_get_edid(connector, &tc->aux.ddc);
}
--
2.34.1

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