[PATCH 1/3] drm/edid: add a helper function to extract the speaker allocation data block

[Alex Deucher]

On Wed, Aug 14, 2013 at 4:14 AM, Ville Syrjälä
<ville.syrjala at linux.intel.com> wrote:
> On Tue, Aug 13, 2013 at 05:01:38PM -0400, Alex Deucher wrote:
>> 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.
>>
>> Signed-off-by: Alex Deucher <alexander.deucher at amd.com>
>> ---
>>  drivers/gpu/drm/drm_edid.c | 50 ++++++++++++++++++++++++++++++++++++++++++++++
>>  include/drm/drm_edid.h     |  1 +
>>  2 files changed, 51 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
>> index 70fc133..bc16c80 100644
>> --- a/drivers/gpu/drm/drm_edid.c
>> +++ b/drivers/gpu/drm/drm_edid.c
>> @@ -2735,6 +2735,56 @@ 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.
>> + *
>> + * 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;
>> +     u8 *cea;
>
> Can be const.
>

fixed.

>> +
>> +     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];
>
> Also const.

fixed.

>
>> +
>> +             if (cea_db_tag(db) == SPEAKER_BLOCK) {
>> +                     dbl = cea_db_payload_len(db);
>> +
>> +                     /* Speaker Allocation Data Block */
>> +                     if (dbl >= 1) {
>
> CEA-861-E says the length must be exactly 3. Maybe we should be
> strict with this check?
>

Sure.

> Also the second payload byte also contains three valid bits. Do
> we not care about those speakers?

Updated patches on the way.

Alex

>
>> +                             *sadb = db[1];
>> +                             count = 1;
>> +                             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
>>   * @mode: the display mode
>> diff --git a/include/drm/drm_edid.h b/include/drm/drm_edid.h
>> index fc481fc..22d7985 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,
>> --
>> 1.8.3.1
>>
>> _______________________________________________
>> dri-devel mailing list
>> dri-devel at lists.freedesktop.org
>> http://lists.freedesktop.org/mailman/listinfo/dri-devel
>
> --
> Ville Syrjälä
> Intel OTC