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drm/edid: add a helper function to extract the speaker allocation data block (v3)

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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 <alexander.deucher@amd.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Tested-by: Rafał Miłecki <zajec5@gmail.com>
This commit is contained in:
Alex Deucher 2013-07-25 15:55:32 -04:00
parent 2483b4ea98
commit d105f4768a
2 changed files with 53 additions and 0 deletions
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52
drivers/gpu/drm/drm_edid.c
View File

@ -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

1
include/drm/drm_edid.h
View File

@ -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,