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If the DisplayPort drivers use display-connector for the HPD detection,
the internal HPD state machine might be not active and thus the hardware
might be not able to handle cable detection correctly. Instead it will
depend on the external HPD notifications to set the cable state,
bypassing the internal HPD state machine (for example this is the case
for the msm DP driver).
However if the cable has been plugged before the HPD IRQ has been
enabled, there will be no HPD event coming. The drivers might fail
detection in such a case. Trigger the HPD notification after enabling
the HPD IRQ, propagating the cable insertion state.
Note, this issue only affects drivers which set OP_HPD but not OP_DETECT
(like dp-connector). Here DP differs from HDMI. For HDMI there is no
additional state or extra "bridge with no sinks plugged" cases. The HPD
pin state is equal to the display plugged state. Nor do we have an AUX
bus with timeouts, etc.
Fixes: 2e2bf3a558 ("drm/bridge: display-connector: add DP support")
Reported-by: Yongxing Mou <yongxing.mou@oss.qualcomm.com>
Reviewed-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Link: https://patch.msgid.link/20260528-dp-connector-hpd-v3-3-d656eb1079b7@oss.qualcomm.com
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
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