Add an iterator for CTA Data Blocks across EDID CTA Extensions and DisplayID CTA Data Blocks.
v2: Update references, note why we can trust displayid ranges (Ville)
Cc: Ville Syrjälä ville.syrjala@linux.intel.com Signed-off-by: Jani Nikula jani.nikula@intel.com --- drivers/gpu/drm/drm_edid.c | 202 ++++++++++++++++++++++++++++++++++--- 1 file changed, 190 insertions(+), 12 deletions(-)
diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c index 40ffd7aba157..43d9e04f8fb9 100644 --- a/drivers/gpu/drm/drm_edid.c +++ b/drivers/gpu/drm/drm_edid.c @@ -4360,24 +4360,12 @@ do_hdmi_vsdb_modes(struct drm_connector *connector, const u8 *db, u8 len, return modes; }
-static int -cea_db_payload_len(const u8 *db) -{ - return db[0] & 0x1f; -} - static int cea_db_extended_tag(const u8 *db) { return db[1]; }
-static int -cea_db_tag(const u8 *db) -{ - return db[0] >> 5; -} - static int cea_revision(const u8 *cea) { @@ -4433,6 +4421,196 @@ cea_db_offsets(const u8 *cea, int *start, int *end) return 0; }
+/* + * CTA Data Block iterator. + * + * Iterate through all CTA Data Blocks in both EDID CTA Extensions and DisplayID + * CTA Data Blocks. + * + * struct cea_db *db: + * struct cea_db_iter iter; + * + * cea_db_iter_edid_begin(edid, &iter); + * cea_db_iter_for_each(db, &iter) { + * // do stuff with db + * } + * cea_db_iter_end(&iter); + */ +struct cea_db_iter { + struct drm_edid_iter edid_iter; + struct displayid_iter displayid_iter; + + /* Current Data Block Collection. */ + const u8 *collection; + + /* Current Data Block index in current collection. */ + int index; + + /* End index in current collection. */ + int end; +}; + +/* CTA-861-H section 7.4 CTA Data BLock Collection */ +struct cea_db { + u8 tag_length; + u8 data[]; +} __packed; + +static int cea_db_tag(const void *_db) +{ + /* FIXME: Transition to passing struct cea_db * everywhere. */ + const struct cea_db *db = _db; + + return db->tag_length >> 5; +} + +static int cea_db_payload_len(const void *_db) +{ + /* FIXME: Transition to passing struct cea_db * everywhere. */ + const struct cea_db *db = _db; + + return db->tag_length & 0x1f; +} + +static const void *cea_db_data(const struct cea_db *db) +{ + return db->data; +} + +static void cea_db_iter_edid_begin(const struct edid *edid, struct cea_db_iter *iter) +{ + memset(iter, 0, sizeof(*iter)); + + drm_edid_iter_begin(edid, &iter->edid_iter); + displayid_iter_edid_begin(edid, &iter->displayid_iter); +} + +static const struct cea_db * +__cea_db_iter_current_block(const struct cea_db_iter *iter) +{ + const struct cea_db *db; + + if (!iter->collection) + return NULL; + + db = (const struct cea_db *)&iter->collection[iter->index]; + + if (iter->index + sizeof(*db) <= iter->end && + iter->index + sizeof(*db) + cea_db_payload_len(db) <= iter->end) + return db; + + return NULL; +} + +/* + * References: + * - VESA E-EDID v1.4 + * - CTA-861-H section 7.3.3 CTA Extension Version 3 + */ +static const void *__cea_db_iter_edid_next(struct cea_db_iter *iter) +{ + const u8 *ext; + + drm_edid_iter_for_each(ext, &iter->edid_iter) { + /* Only support CTA Extension revision 3+ */ + if (ext[0] != CEA_EXT || cea_revision(ext) < 3) + continue; + + iter->index = 4; + iter->end = ext[2]; + if (iter->end == 0) + iter->end = 127; + if (iter->end < 4 || iter->end > 127) + continue; + + return ext; + } + + return NULL; +} + +/* + * References: + * - DisplayID v1.3 Appendix C: CEA Data Block within a DisplayID Data Block + * - DisplayID v2.0 section 4.10 CTA DisplayID Data Block + * + * Note that the above do not specify any connection between DisplayID Data + * Block revision and CTA Extension versions. + */ +static const void *__cea_db_iter_displayid_next(struct cea_db_iter *iter) +{ + const struct displayid_block *block; + + displayid_iter_for_each(block, &iter->displayid_iter) { + if (block->tag != DATA_BLOCK_CTA) + continue; + + /* + * The displayid iterator has already verified the block bounds + * in displayid_iter_block(). + */ + iter->index = sizeof(*block); + iter->end = iter->index + block->num_bytes; + + return block; + } + + return NULL; +} + +static const struct cea_db *__cea_db_iter_next(struct cea_db_iter *iter) +{ + const struct cea_db *db; + + if (iter->collection) { + /* Current collection should always be valid. */ + db = __cea_db_iter_current_block(iter); + if (WARN_ON(!db)) { + iter->collection = NULL; + return NULL; + } + + /* Next block in CTA Data Block Collection */ + iter->index += sizeof(*db) + cea_db_payload_len(db); + + db = __cea_db_iter_current_block(iter); + if (db) + return db; + } + + for (;;) { + /* + * Find the next CTA Data Block Collection. First iterate all + * the EDID CTA Extensions, then all the DisplayID CTA blocks. + * + * Per DisplayID v1.3 Appendix B: DisplayID as an EDID + * Extension, it's recommended that DisplayID extensions are + * exposed after all of the CTA Extensions. + */ + iter->collection = __cea_db_iter_edid_next(iter); + if (!iter->collection) + iter->collection = __cea_db_iter_displayid_next(iter); + + if (!iter->collection) + return NULL; + + db = __cea_db_iter_current_block(iter); + if (db) + return db; + } +} + +#define cea_db_iter_for_each(__db, __iter) \ + while (((__db) = __cea_db_iter_next(__iter))) + +static void cea_db_iter_end(struct cea_db_iter *iter) +{ + displayid_iter_end(&iter->displayid_iter); + drm_edid_iter_end(&iter->edid_iter); + + memset(iter, 0, sizeof(*iter)); +} + static bool cea_db_is_hdmi_vsdb(const u8 *db) { if (cea_db_tag(db) != CTA_DB_VENDOR)