Add handling of EDID extension blocks.

1 files changed, 22 insertions, 4 deletions

diff --git a/vbe.c b/vbe.c
index 8eb74fc..56882d3 100644
--- a/vbe.c
+++ b/vbe.c
@@ -209,11 +209,10 @@ static int vbe_check_ddc_capabilities(int port)
   return 1;
 }
 
-static int vbe_get_edid_info(char *edid, int port)
+static int vbe_get_edid_info(char *edid, int port, int block)
 {
   int i;
   unsigned char *mem;
-  const int EDID_BLOCK_SIZE = 128;
   struct LRMI_regs regs;
 
   /* initialize LRMI */
@@ -235,6 +234,7 @@ static int vbe_get_edid_info(char *edid, int port)
   regs.eax = 0x4f15;
   regs.ebx = 0x0001;
   regs.ecx = port;
+  regs.edx = block;
   regs.es = (uintptr_t)(mem - LRMI_base_addr()) >> 4;
   regs.edi = (uintptr_t)(mem - LRMI_base_addr()) & 0x0f;
 
@@ -262,6 +262,7 @@ static int vbe_get_edid_info(char *edid, int port)
 
 int get_edid(char *edid, int port)
 {
+  int i, extensions;
   int ok = 0;
 
   if (getuid() != 0) {
@@ -272,9 +273,26 @@ int get_edid(char *edid, int port)
   ok =
     (box_is_xbox() || (vbe_check_vbe_info() &&
      vbe_check_ddc_capabilities(port))) &&
-    vbe_get_edid_info(edid, port);
+    vbe_get_edid_info(edid, port, 0);
 
-  return ok ? 128 : 0;
+  if (!ok)
+    return 0;
+
+  extensions = ((unsigned char*)edid)[126];
+  if (extensions > MAX_EXTENSION_COUNT) {
+    log_err("EDID: Reported %d extensions, only reading %d\n",
+            extensions, MAX_EXTENSION_COUNT);
+    extensions = MAX_EXTENSION_COUNT;
+  }
+
+  for (i = 1; i <= extensions; i++) {
+    if (!vbe_get_edid_info(edid + i * EDID_BLOCK_SIZE, port, i)) {
+      log_err("EDID: Failure reading extension block %d\n", i);
+      break;
+    }
+  }
+
+  return i * EDID_BLOCK_SIZE;
 }
 
 int box_is_xbox() {