diff options
Diffstat (limited to 'drivers/gpu/drm/i915/display/intel_dp_mst.c')
| -rw-r--r-- | drivers/gpu/drm/i915/display/intel_dp_mst.c | 40 |
1 files changed, 40 insertions, 0 deletions
diff --git a/drivers/gpu/drm/i915/display/intel_dp_mst.c b/drivers/gpu/drm/i915/display/intel_dp_mst.c index 27ce5c3f5951..17978a1f9ab0 100644 --- a/drivers/gpu/drm/i915/display/intel_dp_mst.c +++ b/drivers/gpu/drm/i915/display/intel_dp_mst.c @@ -1998,3 +1998,43 @@ bool intel_dp_mst_crtc_needs_modeset(struct intel_atomic_state *state, return false; } + +/* + * intel_dp_mst_verify_dpcd_state - verify the MST SW enabled state wrt. the DPCD + * @intel_dp: DP port object + * + * Verify if @intel_dp's MST enabled SW state matches the corresponding DPCD + * state. A long HPD pulse - not long enough to be detected as a disconnected + * state - could've reset the DPCD state, which requires tearing + * down/recreating the MST topology. + * + * Returns %true if the SW MST enabled and DPCD states match, %false + * otherwise. + */ +bool intel_dp_mst_verify_dpcd_state(struct intel_dp *intel_dp) +{ + struct intel_display *display = to_intel_display(intel_dp); + struct intel_connector *connector = intel_dp->attached_connector; + struct intel_digital_port *dig_port = dp_to_dig_port(intel_dp); + struct intel_encoder *encoder = &dig_port->base; + int ret; + u8 val; + + if (!intel_dp->is_mst) + return true; + + ret = drm_dp_dpcd_readb(intel_dp->mst_mgr.aux, DP_MSTM_CTRL, &val); + + /* Adjust the expected register value for SST + SideBand. */ + if (ret < 0 || val != (DP_MST_EN | DP_UP_REQ_EN | DP_UPSTREAM_IS_SRC)) { + drm_dbg_kms(display->drm, + "[CONNECTOR:%d:%s][ENCODER:%d:%s] MST mode got reset, removing topology (ret=%d, ctrl=0x%02x)\n", + connector->base.base.id, connector->base.name, + encoder->base.base.id, encoder->base.name, + ret, val); + + return false; + } + + return true; +} |