From 12e20b80a50906dcb24f45dc85b4ee9cb40a9b16 Mon Sep 17 00:00:00 2001
From: CallumHopkins181 <100864965+CallumHopkins181@users.noreply.github.com>
Date: Sun, 3 Apr 2022 10:02:23 +0100
Subject: [PATCH] Fix rpi4 drm bug (#7749)

* Fix rpi4 drm bug

* Change default path to include all cards

* Import namespaces

Co-authored-by: Jumar Macato <16554748+jmacato@users.noreply.github.com>
---
 .../Output/DrmBindings.cs                     | 28 ++++++++++++++++---
 1 file changed, 24 insertions(+), 4 deletions(-)

diff --git a/src/Linux/Avalonia.LinuxFramebuffer/Output/DrmBindings.cs b/src/Linux/Avalonia.LinuxFramebuffer/Output/DrmBindings.cs
index e218da5f41..64fafc65f3 100644
--- a/src/Linux/Avalonia.LinuxFramebuffer/Output/DrmBindings.cs
+++ b/src/Linux/Avalonia.LinuxFramebuffer/Output/DrmBindings.cs
@@ -1,7 +1,9 @@
 using System;
+using System.IO;
 using System.Collections.Generic;
 using System.ComponentModel;
 using System.Runtime.InteropServices;
+using System.Text.RegularExpressions;
 using static Avalonia.LinuxFramebuffer.NativeUnsafeMethods;
 using static Avalonia.LinuxFramebuffer.Output.LibDrm;
 
@@ -142,10 +144,28 @@ namespace Avalonia.LinuxFramebuffer.Output
         public int Fd { get; private set; }
         public DrmCard(string path = null)
         {
-            path = path ?? "/dev/dri/card0";
-            Fd = open(path, 2, 0);
-            if (Fd == -1)
-                throw new Win32Exception("Couldn't open " + path);
+            if(path == null)
+            {
+                var files = Directory.GetFiles("/dev/dri/");
+
+                foreach(var file in files) 
+                {
+                    var match = Regex.Match(file, "card[0-9]+");
+
+                    if(match.Success)
+                    {
+                        Fd = open(file, 2, 0);
+                        if(Fd != -1) break; 
+                    }    
+                }
+
+                if(Fd == -1) throw new Win32Exception("Couldn't open /dev/dri/card[0-9]+");
+            }
+            else 
+            {
+                Fd = open(path, 2, 0);
+                if(Fd != -1) throw new Win32Exception($"Couldn't open {path}");
+            }
         }
 
         public DrmResources GetResources() => new DrmResources(Fd);