2 files changed, 43 insertions, 1 deletions

diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index 3d6abde8e785..30b286ba16c4 100644
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -685,6 +685,33 @@ EXPORT_SYMBOL(drm_mode_find_dmt);
 typedef void detailed_cb(struct detailed_timing *timing, void *closure);
 
 static void
+cea_for_each_detailed_block(u8 *ext, detailed_cb *cb, void *closure)
+{
+        int i, n = 0;
+        u8 rev = ext[0x01], d = ext[0x02];
+        u8 *det_base = ext + d;
+
+        switch (rev) {
+        case 0:
+                /* can't happen */
+                return;
+        case 1:
+                /* have to infer how many blocks we have, check pixel clock */
+                for (i = 0; i < 6; i++)
+                        if (det_base[18*i] || det_base[18*i+1])
+                                n++;
+                break;
+        default:
+                /* explicit count */
+                n = min(ext[0x03] & 0x0f, 6);
+                break;
+        }
+
+        for (i = 0; i < n; i++)
+                cb((struct detailed_timing *)(det_base + 18 * i), closure);
+}
+
+static void
 drm_for_each_detailed_block(u8 *raw_edid, detailed_cb *cb, void *closure)
 {
         int i;
@@ -696,7 +723,16 @@ drm_for_each_detailed_block(u8 *raw_edid, detailed_cb *cb, void *closure)
         for (i = 0; i < EDID_DETAILED_TIMINGS; i++)
                 cb(&(edid->detailed_timings[i]), closure);
 
-        /* XXX extension block walk */
+        for (i = 1; i <= raw_edid[0x7e]; i++) {
+                u8 *ext = raw_edid + (i * EDID_LENGTH);
+                switch (*ext) {
+                case CEA_EXT:
+                        cea_for_each_detailed_block(ext, cb, closure);
+                        break;
+                default:
+                        break;
+                }
+        }
 }
 
 static void
diff --git a/include/drm/drm_edid.h b/include/drm/drm_edid.h
index 39e2cc5c7e66..5881fad91faa 100644
--- a/include/drm/drm_edid.h
+++ b/include/drm/drm_edid.h
@@ -28,6 +28,12 @@
 #define EDID_LENGTH 128
 #define DDC_ADDR 0x50
 
+#define CEA_EXT     0x02
+#define VTB_EXT     0x10
+#define DI_EXT      0x40
+#define LS_EXT      0x50
+#define MI_EXT      0x60
+
 struct est_timings {
         u8 t1;
         u8 t2;