From d105f4768a959f22078820625ccec9b693f164c8 Mon Sep 17 00:00:00 2001 From: Alex Deucher Date: Thu, 25 Jul 2013 15:55:32 -0400 Subject: [PATCH] drm/edid: add a helper function to extract the speaker allocation data block (v3) MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit 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 Syrjälä's comments v3: fix copy/paste typo in memory allocation Signed-off-by: Alex Deucher Reviewed-by: Ville Syrjälä Tested-by: Rafał Miłecki --- 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 70fc1335e331..58b4882feedf 100644 --- a/drivers/gpu/drm/drm_edid.c +++ b/drivers/gpu/drm/drm_edid.c @@ -2734,6 +2734,58 @@ 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 diff --git a/include/drm/drm_edid.h b/include/drm/drm_edid.h index fc481fc17085..c76a129b9953 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, -- 2.30.2