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

[Anssi Hannula]

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)?

Not sure this matters much, though, since the only consumer here is ALSA
which we can write however we wish (and it is missing handling for 255
since it was missing from AMD_HDA_verbs_v2.pdf, but I'll add it in any
case since it is mentioned in HDMI specs).

[...]

-- 
Anssi Hannula