[PATCH 1/3] drm/edid: add a helper function to extract the speaker allocation data block (v2)

[Alex Deucher]

On Wed, Aug 14, 2013 at 12:17 PM, Ville Syrjälä
<ville.syrjala at linux.intel.com> wrote:
> On Wed, Aug 14, 2013 at 12:08:13PM -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.
>>
>> v2: update per Ville Syrjälä's comments
>>
>> Signed-off-by: Alex Deucher <alexander.deucher at amd.com>
>> ---
>>  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 70fc133..2e36d28 100644
>> --- a/drivers/gpu/drm/drm_edid.c
>> +++ b/drivers/gpu/drm/drm_edid.c
>> @@ -2735,6 +2735,58 @@ 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 = kcalloc(count, dbl, GFP_KERNEL);
>
> 'count' not initialized yet. I suppose it was supposed to be just
> kmalloc(dbl, GFP_KERNEL). But since it's just three bytes, making
> the user just pass in a pointer to u32 would work just as well
> w/o requiring the dynamic alloc/free.

whoops, that was just a copy paste error.  I'll fix that.
I suppose we could just use a u32 unless the size of the block changes
in the future.

Alex

>
>> +                             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
>>   * @mode: the display mode
>> diff --git a/include/drm/drm_edid.h b/include/drm/drm_edid.h
>> index fc481fc..c76a129 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
>>
>> _______________________________________________
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>> dri-devel at lists.freedesktop.org
>> http://lists.freedesktop.org/mailman/listinfo/dri-devel
>
> --
> Ville Syrjälä
> Intel OTC