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authorMa Ling <ling.ma@intel.com>2009-03-26 19:26:23 +0800
committerDave Airlie <airlied@redhat.com>2009-03-29 18:31:49 +1000
commitf23c20c83d523e5f8cda1f8f7ed52fe6afffbe29 (patch)
treec0888eeee7f76b46151264294222bf74190b385c /drivers/gpu
parentdba5ed0cd12d8db5c0d2e1c869c2a50c5bcf6743 (diff)
drm: detect hdmi monitor by hdmi identifier (v3)
Sometime we need to communicate with HDMI monitor by sending audio or video info frame, so we have to know monitor type. However if user utilize HDMI-DVI adapter to connect DVI monitor, hardware detection will incorrectly show the monitor is HDMI. HDMI spec tell us that any device containing IEEE registration Identifier will be treated as HDMI device. The patch intends to detect HDMI monitor by this rule. Signed-off-by: Ma Ling <ling.ma@intel.com> Signed-off-by: Dave Airlie <airlied@redhat.com>
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