At least a ParadTech PS175 LSPCON chip/firmware uses long instead of short pulses to signal output unplug/plug events. This is contrary to how branch devices normally work which use short HPD signaling. This chip will also switch to LS mode after an unplug event, which could be the consequence of the long HPD signaling semantics and an effort to save power automatically. Because of this we'll fail to do AUX and detect the output after a replug event. To fix this make sure we are in PCON mode during connector detection. v2: - Switch the mode in the proper spot. Cc: raptorteak@xxxxxxxxx Cc: Shashank Sharma <shashank.sharma@xxxxxxxxx> Cc: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=98912 Reported-and-tested-by: raptorteak@xxxxxxxxx Signed-off-by: Imre Deak <imre.deak@xxxxxxxxx> --- drivers/gpu/drm/i915/intel_dp.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c index 024798a..e1529ff 100644 --- a/drivers/gpu/drm/i915/intel_dp.c +++ b/drivers/gpu/drm/i915/intel_dp.c @@ -4326,9 +4326,13 @@ intel_dp_short_pulse(struct intel_dp *intel_dp) static enum drm_connector_status intel_dp_detect_dpcd(struct intel_dp *intel_dp) { + struct intel_lspcon *lspcon = dp_to_lspcon(intel_dp); uint8_t *dpcd = intel_dp->dpcd; uint8_t type; + if (lspcon->active) + lspcon_resume(lspcon); + if (!intel_dp_get_dpcd(intel_dp)) return connector_status_disconnected; -- 2.5.0 _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
