drm: detect hdmi monitor by hdmi identifier (v3)

[mv-sheeva.git] / drivers / gpu / drm / drm_edid.c

diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index fab2bdf9c4235d5af98b09f2be27f75992c11f0e..c67400067b8573c9be015391601152dc4acd6f90 100644 (file)
--- 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