From 11a8d095d86854bbc8697525f2c543de36bf5804 Mon Sep 17 00:00:00 2001 From: Jani Nikula Date: Wed, 8 Jun 2022 10:50:32 +0300 Subject: [PATCH] drm/edid: abstract cea data block collection size MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Add a function to get the cea data block collection size. Cc: Ville Syrjälä Signed-off-by: Jani Nikula Reviewed-by: Ville Syrjälä Link: https://patchwork.freedesktop.org/patch/msgid/5339ab3249400a3c41001967e7ff2611b58e0425.1654674560.git.jani.nikula@intel.com --- drivers/gpu/drm/drm_edid.c | 24 +++++++++++++++++++++--- 1 file changed, 21 insertions(+), 3 deletions(-) diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c index c57f6333ea7d..002816509fc8 100644 --- a/drivers/gpu/drm/drm_edid.c +++ b/drivers/gpu/drm/drm_edid.c @@ -4482,6 +4482,20 @@ __cea_db_iter_current_block(const struct cea_db_iter *iter) return NULL; } +/* + * References: + * - CTA-861-H section 7.3.3 CTA Extension Version 3 + */ +static int cea_db_collection_size(const u8 *cta) +{ + u8 d = cta[2]; + + if (d < 4 || d > 127) + return 0; + + return d - 4; +} + /* * References: * - VESA E-EDID v1.4 @@ -4492,15 +4506,19 @@ 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) { + int size; + /* 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 < 4 || iter->end > 127) + size = cea_db_collection_size(ext); + if (!size) continue; + iter->index = 4; + iter->end = iter->index + size; + return ext; } -- 2.25.1