2 files changed, 63 insertions, 0 deletions

diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index fab2bdf9c423..c67400067b85 100644
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -742,6 +742,68 @@ end:
 }
 EXPORT_SYMBOL(drm_get_edid);
 
+#define HDMI_IDENTIFIER 0x000C03
+#define VENDOR_BLOCK    0x03
+/**
+ * drm_detect_hdmi_monitor - detect whether monitor is hdmi.
+ * @edid: monitor EDID information
+ *
+ * Parse the CEA extension according to CEA-861-B.
+ * Return true if HDMI, false if not or unknown.
+ */
+bool drm_detect_hdmi_monitor(struct edid *edid)
+{
+        char *edid_ext = NULL;
+        int i, hdmi_id, edid_ext_num;
+        int start_offset, end_offset;
+        bool is_hdmi = false;
+
+        /* No EDID or EDID extensions */
+        if (edid == NULL || edid->extensions == 0)
+                goto end;
+
+        /* Chose real EDID extension number */
+        edid_ext_num = edid->extensions > MAX_EDID_EXT_NUM ?
+                       MAX_EDID_EXT_NUM : edid->extensions;
+
+        /* Find CEA extension */
+        for (i = 0; i < edid_ext_num; i++) {
+                edid_ext = (char *)edid + EDID_LENGTH * (i + 1);
+                /* This block is CEA extension */
+                if (edid_ext[0] == 0x02)
+                        break;
+        }
+
+        if (i == edid_ext_num)
+                goto end;
+
+        /* Data block offset in CEA extension block */
+        start_offset = 4;
+        end_offset = edid_ext[2];
+
+        /*
+         * Because HDMI identifier is in Vendor Specific Block,
+         * search it from all data blocks of CEA extension.
+         */
+        for (i = start_offset; i < end_offset;
+                /* Increased by data block len */
+                i += ((edid_ext[i] & 0x1f) + 1)) {
+                /* Find vendor specific block */
+                if ((edid_ext[i] >> 5) == VENDOR_BLOCK) {
+                        hdmi_id = edid_ext[i + 1] | (edid_ext[i + 2] << 8) |
+                                  edid_ext[i + 3] << 16;
+                        /* Find HDMI identifier */
+                        if (hdmi_id == HDMI_IDENTIFIER)
+                                is_hdmi = true;
+                        break;
+                }
+        }
+
+end:
+        return is_hdmi;
+}
+EXPORT_SYMBOL(drm_detect_hdmi_monitor);
+
 /**
  * drm_add_edid_modes - add modes from EDID data, if available
  * @connector: connector we're probing
diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h
index 9022b2468182..3c1924c010e8 100644
--- a/include/drm/drm_crtc.h
+++ b/include/drm/drm_crtc.h
@@ -732,4 +732,5 @@ extern int drm_mode_gamma_get_ioctl(struct drm_device *dev,
                                     void *data, struct drm_file *file_priv);
 extern int drm_mode_gamma_set_ioctl(struct drm_device *dev,
                                     void *data, struct drm_file *file_priv);
+extern bool drm_detect_hdmi_monitor(struct edid *edid);
 #endif /* __DRM_CRTC_H__ */