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[Why] USB-C DisplayPort Alt Mode with concurrent USB data needs lane count limitation to prevent incorrect 4-lane DP configuration when only 2 lanes are available due to hardware lane sharing between DP and USB3. [How] Query DMUB for Alt Mode status (is_dp_alt_disable, is_usb, is_dp4) in dcn32_link_encoder_get_max_link_cap() and cap DP to 2 lanes when USB is active on USB-C port. Added inline documentation explaining the USB-C lane sharing constraint. Reviewed-by: PeiChen Huang <peichen.huang@amd.com> Signed-off-by: LinCheng Ku <lincheng.ku@amd.com> Signed-off-by: Chenyu Chen <chen-yu.chen@amd.com> Tested-by: Daniel Wheeler <daniel.wheeler@amd.com> Signed-off-by: Alex Deucher <alexander.deucher@amd.com>