From cfde03ec9bbb3a5487443e879eadd0c5cbc0030c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Herv=C3=A9=20Poussineau?= <hpoussin@reactos.org>
Date: Fri, 28 Mar 2025 23:01:10 +0100
Subject: [PATCH] [VIDEOPRT] Write monitor EDID to registry

This will be used later by win32k to give only valid display modes
to user mode.
---
 win32ss/drivers/videoprt/child.c | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/win32ss/drivers/videoprt/child.c b/win32ss/drivers/videoprt/child.c
index 71ca44cbe87..dd3a8beaed9 100644
--- a/win32ss/drivers/videoprt/child.c
+++ b/win32ss/drivers/videoprt/child.c
@@ -121,6 +121,8 @@ IntVideoPortChildQueryId(
 {
     PWCHAR Buffer = NULL, StaticBuffer;
     UNICODE_STRING UnicodeStr;
+    HANDLE hKey;
+    NTSTATUS Status;
 
     switch (IrpSp->Parameters.QueryId.IdType)
     {
@@ -197,6 +199,22 @@ IntVideoPortChildQueryId(
                         /* Add the second null terminator */
                         Buffer[wcslen(StaticBuffer) + 1] = UNICODE_NULL;
                     }
+
+                    /* Try to write EDID to registry (ignore errors) */
+                    Status = IoOpenDeviceRegistryKey(ChildExtension->PhysicalDeviceObject,
+                                                     PLUGPLAY_REGKEY_DEVICE,
+                                                     MAXIMUM_ALLOWED,
+                                                     &hKey);
+                    if (NT_SUCCESS(Status))
+                    {
+                        Status = RtlWriteRegistryValue(RTL_REGISTRY_HANDLE,
+                                              hKey,
+                                              ChildExtension->EdidValid ? L"EDID" : L"BAD_EDID",
+                                              REG_BINARY,
+                                              ChildExtension->ChildDescriptor,
+                                              sizeof(ChildExtension->ChildDescriptor));
+                        ZwClose(hKey);
+                    }
                     break;
                 default:
                     ASSERT(FALSE);