summaryrefslogtreecommitdiffstats
path: root/drivers/gpu
diff options
context:
space:
mode:
Diffstat (limited to 'drivers/gpu')
-rw-r--r--drivers/gpu/drm/drm_edid.c62
1 files changed, 62 insertions, 0 deletions
diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index fab2bdf9c42..c67400067b8 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