[PATCH 1/2] drm/radeon/audio: write audio/video latency info for DCE4/5

[Alex Deucher]

On Fri, Nov 8, 2013 at 6:24 AM, Anssi Hannula <anssi.hannula at iki.fi> wrote:
> 18.10.2013 23:41, Alex Deucher kirjoitti:
>> Needed by the hda driver to properly set up synchronization
>> on the audio side.
>>
>> Signed-off-by: Alex Deucher <alexander.deucher at amd.com>
>> ---
>>  drivers/gpu/drm/radeon/evergreen_hdmi.c | 37 ++++++++++++++++++++++++++++++++
>>  drivers/gpu/drm/radeon/evergreend.h     | 38 +++++++++++++++++++++++++++++++++
>>  2 files changed, 75 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/radeon/evergreen_hdmi.c b/drivers/gpu/drm/radeon/evergreen_hdmi.c
>> index 5fbe486..abdc893 100644
>> --- a/drivers/gpu/drm/radeon/evergreen_hdmi.c
>> +++ b/drivers/gpu/drm/radeon/evergreen_hdmi.c
> [...]
>> +             if (connector->latency_present[0])
>> +                     tmp = VIDEO_LIPSYNC(connector->video_latency[0]) |
>> +                             AUDIO_LIPSYNC(connector->audio_latency[0]);
>> +             else
>> +                     tmp = VIDEO_LIPSYNC(255) | AUDIO_LIPSYNC(255);
>> +     }
>> +     WREG32(AZ_F0_CODEC_PIN0_CONTROL_RESPONSE_LIPSYNC, tmp);
> [...]
>> +#define AZ_F0_CODEC_PIN0_CONTROL_RESPONSE_LIPSYNC         0x5fe8
>> +#       define VIDEO_LIPSYNC(x)                           (((x) & 0xff) << 0)
>> +#       define AUDIO_LIPSYNC(x)                           (((x) & 0xff) << 8)
>> +/* VIDEO_LIPSYNC, AUDIO_LIPSYNC
>> + * 0   = invalid
>> + * x   = legal delay value
>> + * 255 = sync not supported
>> + */
>
> Hmm, AMD_HDA_verbs_v2.pdf says that:
> 0      = unknown latency
>
> HDMI spec 1.4 says that:
> 0      = not valid or unknown latency
> 1..251 = valid delay value
> 255    = video not supported / audio not supported
>
> Are you sure you shouldn't use 0 instead for unknown (no latency_present)?

I'm not sure.  The comment in the code above is what the register spec
says which seems to match the HDMI spec.  I can dig around a bit more
internally.

Alex