This adds a helper function to extract the speaker allocation
data block from the EDID. This data block describes what speakers
are present on the display device.
v2: update per Ville Syrj?l?'s comments
v3: fix copy/paste typo in memory allocation
Signed-off-by: Alex Deucher <alexander.deucher at amd.com>
Reviewed-by: Ville Syrj?l? <ville.syrjala at linux.intel.com>
---
drivers/gpu/drm/drm_edid.c | 52 ++++++++++++++++++++++++++++++++++++++++++++++
include/drm/drm_edid.h | 1 +
2 files changed, 53 insertions(+)
diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index 70fc133..58b4882 100644
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -2735,6 +2735,58 @@ int drm_edid_to_sad(struct edid *edid, struct cea_sad
**sads)
EXPORT_SYMBOL(drm_edid_to_sad);
/**
+ * drm_edid_to_speaker_allocation - extracts Speaker Allocation Data Blocks
from EDID
+ * @edid: EDID to parse
+ * @sadb: pointer to the speaker block
+ *
+ * Looks for CEA EDID block and extracts the Speaker Allocation Data Block
from it.
+ * Note: returned pointer needs to be kfreed
+ *
+ * Return number of found Speaker Allocation Blocks or negative number on
error.
+ */
+int drm_edid_to_speaker_allocation(struct edid *edid, u8 **sadb)
+{
+ int count = 0;
+ int i, start, end, dbl;
+ const u8 *cea;
+
+ cea = drm_find_cea_extension(edid);
+ if (!cea) {
+ DRM_DEBUG_KMS("SAD: no CEA Extension found\n");
+ return -ENOENT;
+ }
+
+ if (cea_revision(cea) < 3) {
+ DRM_DEBUG_KMS("SAD: wrong CEA revision\n");
+ return -ENOTSUPP;
+ }
+
+ if (cea_db_offsets(cea, &start, &end)) {
+ DRM_DEBUG_KMS("SAD: invalid data block offsets\n");
+ return -EPROTO;
+ }
+
+ for_each_cea_db(cea, i, start, end) {
+ const u8 *db = &cea[i];
+
+ if (cea_db_tag(db) == SPEAKER_BLOCK) {
+ dbl = cea_db_payload_len(db);
+
+ /* Speaker Allocation Data Block */
+ if (dbl == 3) {
+ *sadb = kmalloc(dbl, GFP_KERNEL);
+ memcpy(*sadb, &db[1], dbl);
+ count = dbl;
+ break;
+ }
+ }
+ }
+
+ return count;
+}
+EXPORT_SYMBOL(drm_edid_to_speaker_allocation);
+
+/**
* drm_av_sync_delay - HDMI/DP sink audio-video sync delay in millisecond
* @connector: connector associated with the HDMI/DP sink
* @mode: the display mode
diff --git a/include/drm/drm_edid.h b/include/drm/drm_edid.h
index fc481fc..c76a129 100644
--- a/include/drm/drm_edid.h
+++ b/include/drm/drm_edid.h
@@ -259,6 +259,7 @@ struct hdmi_avi_infoframe;
void drm_edid_to_eld(struct drm_connector *connector, struct edid *edid);
int drm_edid_to_sad(struct edid *edid, struct cea_sad **sads);
+int drm_edid_to_speaker_allocation(struct edid *edid, u8 **sadb);
int drm_av_sync_delay(struct drm_connector *connector,
struct drm_display_mode *mode);
struct drm_connector *drm_select_eld(struct drm_encoder *encoder,
--
1.8.3.1
