dp: assume sink capabilities on force-enabled connectors without DPCD

src/common/displayport/src/dp_configcaps.cpp

@@ -185,6 +185,12 @@ void DPCDHALImpl::parseAndReadCaps()
         // Set an invalid state here and make sure we REMEMBER we couldn't get the caps
         caps.revisionMajor = 0;
         dpcdOffline = true;
+
+        //
+        // Forced/sink-less connector (EDID override, no AUX): fall back to
+        // fake caps so discovery can proceed and create a device.
+        //
+        populateFakeDpcd();
         return;
     }
 
@@ -634,6 +640,14 @@ bool DPCDHALImpl::getSDPExtnForColorimetry()
 {
     bool bSDPExtnForColorimetry = false;
     NvU8 byte = 0;
+    if (dpcdOffline)
+    {
+        //
+        // Forced/sink-less connector: claim VSC SDP colorimetry support so
+        // HDR signaling can be enabled. No real sink interprets the SDP.
+        //
+        return true;
+    }
     if (caps.extendedRxCapsPresent)
     {
         if (AuxRetry::ack == bus.read(NV_DPCD14_EXTENDED_DPRX_FEATURE_ENUM_LIST, &byte,  sizeof byte))
@@ -996,7 +1010,7 @@ void DPCDHALImpl::populateFakeDpcd()
     // this should be extended in for more dpcd offsets in future.
     //
     caps.revisionMajor = 0x1;
-    caps.revisionMinor = 0x1;
+    caps.revisionMinor = 0x4;
     caps.supportsESI = false;
     caps.maxLinkRate = dp2LinkRate_8_10Gbps;
     caps.maxLaneCount = 4;

src/common/displayport/src/dp_deviceimpl.cpp

@@ -1732,6 +1732,15 @@ NvBool DeviceImpl::getDSCSupport()
         }
     }
 
+    else if (hal->isDpcdOffline())
+    {
+        //
+        // Forced/sink-less connector (EDID override, no AUX): assume the
+        // virtual sink can decompress DSC so that high-bandwidth modes pass
+        // validation. The stream is never decoded by a real device.
+        //
+        dscCaps.bDSCDecompressionSupported = true;
+    }
     else
     {
         DP_PRINTF(DP_ERROR, "DP-DEV> DSC Support AUX READ failed for %s!", address.toString(sb));
@@ -2308,6 +2317,11 @@ bool DeviceImpl::getFECSupport()
         bFECSupported = this->bandwidth.enum_path.bPathFECCapable;
     }
 
+    else if (hal->isDpcdOffline())
+    {
+        // Forced/sink-less connector: claim FEC so the DSC path is usable.
+        bFECSupported = true;
+    }
     else if (AuxBus::success == this->getDpcdData(NV_DPCD14_FEC_CAPABILITY,
         &byte, sizeof(byte), &size, &nakReason))
     {
@@ -2560,6 +2574,30 @@ bool DeviceImpl::readAndParseDSCCaps()
     if(AuxBus::success != this->getDpcdData(NV_DPCD14_DSC_SUPPORT,
         &rawDscCaps[0], sizeof(rawDscCaps), &sizeCompleted, &nakReason))
     {
+        if (hal->isDpcdOffline())
+        {
+            //
+            // Forced/sink-less connector: synthesize DSC decoder caps
+            // modeled on a typical DSC 1.2 4K high-refresh monitor.
+            //
+            rawDscCaps[0x0] = 0x01; // decompression supported
+            rawDscCaps[0x1] = 0x21; // DSC algorithm revision 1.2
+            rawDscCaps[0x2] = 0x00; // RC buffer block size
+            rawDscCaps[0x3] = 0x0F; // RC buffer size
+            rawDscCaps[0x4] = 0xFF; // slice caps 1: up to 12 slices
+            rawDscCaps[0x5] = 0x03; // line buffer bit depth: 12
+            rawDscCaps[0x6] = 0x01; // block prediction supported
+            rawDscCaps[0x7] = 0xFF; // max bits per pixel LSB
+            rawDscCaps[0x8] = 0x03; // max bits per pixel MSB (1023/16 bpp)
+            rawDscCaps[0x9] = 0x1F; // color formats: RGB + all YCbCr
+            rawDscCaps[0xA] = 0x0E; // color depth: 8/10/12 bpc
+            rawDscCaps[0xB] = 0xEE; // peak throughput 1000 MP/s both modes
+            rawDscCaps[0xC] = 0x10; // max slice width 5120 px
+            rawDscCaps[0xD] = 0x00; // slice caps 2
+            rawDscCaps[0xE] = 0x00; // branch throughput
+            rawDscCaps[0xF] = 0x00; // bpp increment: 1/16
+            return parseDscCaps(&rawDscCaps[0], sizeof(rawDscCaps));
+        }
         DP_PRINTF(DP_ERROR, "DP-DEV> Error querying DSC Caps on %s!", this->address.toString(sb));
         return false;
     }

src/nvidia-modeset/include/dp/nvdp-connector.h

@@ -37,6 +37,8 @@ void nvDPNotifyLongPulse(NVConnectorEvoPtr pConnectorEvo,
 
 void nvDPNotifyShortPulse(NVDPLibConnectorPtr pNVDpLibConnector);
 
+NvBool nvDPConnectorIsPlugged(const NVConnectorEvoRec *pConnectorEvo);
+
 void nvDPDestroyConnector(NVDPLibConnectorPtr pNVDpLibConnector);
 
 NVDPLibModesetStatePtr nvDPLibCreateModesetState(

src/nvidia-modeset/src/dp/nvdp-connector.cpp

@@ -121,6 +121,12 @@ void nvDPNotifyLongPulse(NVConnectorEvoPtr pConnectorEvo,
 
 }
 
+NvBool nvDPConnectorIsPlugged(const NVConnectorEvoRec *pConnectorEvo)
+{
+    return (pConnectorEvo->pDpLibConnector != NULL) &&
+           pConnectorEvo->pDpLibConnector->plugged;
+}
+
 void nvDPNotifyShortPulse(NVDPLibConnectorPtr pNVDpLibConnector)
 {
     DisplayPort::Connector *c = pNVDpLibConnector->connector;

src/nvidia-modeset/src/nvkms-dpy.c

@@ -22,6 +22,7 @@
  */
 
 #include "dp/nvdp-device.h"
+#include "dp/nvdp-connector.h"
 #include "dp/nvdp-connector-event-sink.h"
 
 #include "nvkms-api-types.h"
@@ -3127,6 +3128,15 @@ NvBool nvDpyGetDynamicData(
         connectedList = nvDPLibDpyIsConnected(pDpyEvo) ?
             oneDpyIdList : nvEmptyDpyIdList();
     } else if (pRequest->forceConnected) {
+        if (nvConnectorUsesDPLib(pConnectorEvo) &&
+            !nvDPConnectorIsPlugged(pConnectorEvo)) {
+            /*
+             * Forced sink-less DP connector (EDID override): simulate a
+             * plug so the DP library performs discovery and creates a
+             * device, enabling DSC/HDR capability paths to be consulted.
+             */
+            nvDPNotifyLongPulse(pConnectorEvo, TRUE);
+        }
         connectedList = oneDpyIdList;
     } else if (pRequest->forceDisconnected) {
         connectedList = nvEmptyDpyIdList();