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List: dri-devel
Subject: Re: [PATCH 1/2] drm/radeon/audio: write audio/video latency info for DCE4/5
From: Anssi Hannula <anssi.hannula () iki ! fi>
Date: 2013-11-11 22:10:00
Message-ID: 528155B8.2000206 () iki ! fi
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11.11.2013 17:55, Alex Deucher kirjoitti:
> On Fri, Nov 8, 2013 at 6:24 AM, Anssi Hannula <anssi.hannula@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@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.
OK, though don't waste too much time on that, ALSA has to handle 0 and
255 the same in any case (a patch has just been pushed to sound git to
handle 255). :)
--
Anssi Hannula
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