diff options
Diffstat (limited to 'drivers/gpu')
| -rw-r--r-- | drivers/gpu/drm/drm_edid.c | 62 |
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 |