drm: add drm_edid_to_eld helper extracting SADs from EDID (v2)
Some devices (ATI/AMD cards) don't support passing ELD struct to the
hardware but just require filling specific registers and then the
hardware/firmware does the rest. In such cases we need to read the info
from SAD blocks and put them in the correct registers.
agd5f: note that the returned pointer needs to be kfreed as per
Christian's suggestion.
v2: fix warning
Signed-off-by: Rafał Miłecki <zajec5@gmail.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index e2acfdb..b6807e8 100644
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -2511,6 +2511,65 @@
EXPORT_SYMBOL(drm_edid_to_eld);
/**
+ * drm_edid_to_sad - extracts SADs from EDID
+ * @edid: EDID to parse
+ * @sads: pointer that will be set to the extracted SADs
+ *
+ * Looks for CEA EDID block and extracts SADs (Short Audio Descriptors) from it.
+ * Note: returned pointer needs to be kfreed
+ *
+ * Return number of found SADs or negative number on error.
+ */
+int drm_edid_to_sad(struct edid *edid, struct cea_sad **sads)
+{
+ int count = 0;
+ int i, start, end, dbl;
+ 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) {
+ u8 *db = &cea[i];
+
+ if (cea_db_tag(db) == AUDIO_BLOCK) {
+ int j;
+ dbl = cea_db_payload_len(db);
+
+ count = dbl / 3; /* SAD is 3B */
+ *sads = kcalloc(count, sizeof(**sads), GFP_KERNEL);
+ if (!*sads)
+ return -ENOMEM;
+ for (j = 0; j < count; j++) {
+ u8 *sad = &db[1 + j * 3];
+
+ (*sads)[j].format = (sad[0] & 0x78) >> 3;
+ (*sads)[j].channels = sad[0] & 0x7;
+ (*sads)[j].freq = sad[1] & 0x7F;
+ (*sads)[j].byte2 = sad[2];
+ }
+ break;
+ }
+ }
+
+ return count;
+}
+EXPORT_SYMBOL(drm_edid_to_sad);
+
+/**
* 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