[PATCH 03/12] drm/edid: Parse the HDMI CEA block and look for 4k modes

Damien Lespiau
2013-08-14T17:19:06Z

HDMI 1.4 adds 4 "4k x 2k" modes in the the CEA vendor specific block.

With this commit, we now parse this block and expose the 4k modes that
we find there.

v2: Fix the "4096x2160" string (nice catch!), add comments about
do_hdmi_vsdb_modes() arguments and make it clearer that offset is
relative to the end of the required fields of the HDMI VSDB
(Ville Syrjälä)

v3: Fix 'Unknow' typo (Simon Farnsworth)

Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>
Tested-by: Cancan Feng <cancan.feng@intel.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=67030
Reviewed-by: Simon Farnsworth <simon.farnsworth@onelan.co.uk>
---
drivers/gpu/drm/drm_edid.c | 124 +++++++++++++++++++++++++++++++++++++++------
1 file changed, 109 insertions(+), 15 deletions(-)

diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index bb25ee2..9de573c 100644
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -931,6 +931,36 @@ static const struct drm_display_mode edid_cea_modes[] = {
.vrefresh = 100, },
};

+/*
+ * HDMI 1.4 4k modes.
+ */
+static const struct drm_display_mode edid_4k_modes[] = {
+ /* 1 - 3840x2160@30Hz */
+ { DRM_MODE("3840x2160", DRM_MODE_TYPE_DRIVER, 297000,
+ 3840, 4016, 4104, 4400, 0,
+ 2160, 2168, 2178, 2250, 0,
+ DRM_MODE_FLAG_PHSYNC | DRM_MODE_FLAG_PVSYNC),
+ .vrefresh = 30, },
+ /* 2 - 3840x2160@25Hz */
+ { DRM_MODE("3840x2160", DRM_MODE_TYPE_DRIVER, 297000,
+ 3840, 4896, 4984, 5280, 0,
+ 2160, 2168, 2178, 2250, 0,
+ DRM_MODE_FLAG_PHSYNC | DRM_MODE_FLAG_PVSYNC),
+ .vrefresh = 25, },
+ /* 3 - 3840x2160@24Hz */
+ { DRM_MODE("3840x2160", DRM_MODE_TYPE_DRIVER, 297000,
+ 3840, 5116, 5204, 5500, 0,
+ 2160, 2168, 2178, 2250, 0,
+ DRM_MODE_FLAG_PHSYNC | DRM_MODE_FLAG_PVSYNC),
+ .vrefresh = 24, },
+ /* 4 - 4096x2160@24Hz (SMPTE) */
+ { DRM_MODE("4096x2160", DRM_MODE_TYPE_DRIVER, 297000,
+ 4096, 5116, 5204, 5500, 0,
+ 2160, 2168, 2178, 2250, 0,
+ DRM_MODE_FLAG_PHSYNC | DRM_MODE_FLAG_PVSYNC),
+ .vrefresh = 24, },
+};
+
/*** DDC fetch and block validation ***/

static const u8 edid_header[] = {
@@ -2465,6 +2495,68 @@ do_cea_modes(struct drm_connector *connector, const u8 *db, u8 len)
return modes;
}

+/*
+ * do_hdmi_vsdb_modes - Parse the HDMI Vendor Specific data block
+ * @connector: connector corresponding to the HDMI sink
+ * @db: start of the CEA vendor specific block
+ * @len: length of the CEA block payload, ie. one can access up to db[len]
+ *
+ * Parses the HDMI VSDB looking for modes to add to @connector.
+ */
+static int
+do_hdmi_vsdb_modes(struct drm_connector *connector, const u8 *db, u8 len)
+{
+ struct drm_device *dev = connector->dev;
+ int modes = 0, offset = 0, i;
+ u8 vic_len;
+
+ if (len < 8)
+ goto out;
+
+ /* no HDMI_Video_Present */
+ if (!(db[8] & (1 << 5)))
+ goto out;
+
+ /* Latency_Fields_Present */
+ if (db[8] & (1 << 7))
+ offset += 2;
+
+ /* I_Latency_Fields_Present */
+ if (db[8] & (1 << 6))
+ offset += 2;
+
+ /* the declared length is not long enough for the 2 first bytes
+ * of additional video format capabilities */
+ offset += 2;
+ if (len < (8 + offset))
+ goto out;
+
+ vic_len = db[8 + offset] >> 5;
+
+ for (i = 0; i < vic_len && len >= (9 + offset + i); i++) {
+ struct drm_display_mode *newmode;
+ u8 vic;
+
+ vic = db[9 + offset + i];
+
+ vic--; /* VICs start at 1 */
+ if (vic >= ARRAY_SIZE(edid_4k_modes)) {
+ DRM_ERROR("Unknown HDMI VIC: %d\n", vic);
+ continue;
+ }
+
+ newmode = drm_mode_duplicate(dev, &edid_4k_modes[vic]);
+ if (!newmode)
+ continue;
+
+ drm_mode_probed_add(connector, newmode);
+ modes++;
+ }
+
+out:
+ return modes;
+}
+
static int
cea_db_payload_len(const u8 *db)
{
@@ -2496,6 +2588,21 @@ cea_db_offsets(const u8 *cea, int *start, int *end)
return 0;
}

+static bool cea_db_is_hdmi_vsdb(const u8 *db)
+{
+ int hdmi_id;
+
+ if (cea_db_tag(db) != VENDOR_BLOCK)
+ return false;
+
+ if (cea_db_payload_len(db) < 5)
+ return false;
+
+ hdmi_id = db[1] | (db[2] << 8) | (db[3] << 16);
+
+ return hdmi_id == HDMI_IDENTIFIER;
+}
+
#define for_each_cea_db(cea, i, start, end) \
for ((i) = (start); (i) < (end) && (i) + cea_db_payload_len(&(cea)[(i)]) < (end); (i) += cea_db_payload_len(&(cea)[(i)]) + 1)

@@ -2519,6 +2626,8 @@ add_cea_modes(struct drm_connector *connector, struct edid *edid)

if (cea_db_tag(db) == VIDEO_BLOCK)
modes += do_cea_modes(connector, db + 1, dbl);
+ else if (cea_db_is_hdmi_vsdb(db))
+ modes += do_hdmi_vsdb_modes(connector, db, dbl);
}
}

@@ -2571,21 +2680,6 @@ monitor_name(struct detailed_timing *t, void *data)
*(u8 **)data = t->data.other_data.data.str.str;
}

-static bool cea_db_is_hdmi_vsdb(const u8 *db)
-{
- int hdmi_id;
-
- if (cea_db_tag(db) != VENDOR_BLOCK)
- return false;
-
- if (cea_db_payload_len(db) < 5)
- return false;
-
- hdmi_id = db[1] | (db[2] << 8) | (db[3] << 16);
-
- return hdmi_id == HDMI_IDENTIFIER;
-}
-
/**
* drm_edid_to_eld - build ELD from EDID
* @connector: connector corresponding to the HDMI/DP sink
--
1.8.3.1

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