[alsa-devel] [PATCH] ALSA: hda - hdmi: Fallback to ALSA allocation when selecting CA

[Ashecrow]

Hi guys,
Let me tell you, you rock!!!!
I have compiled kernel sources from Linus master branch in his GIT repo and it works flawlessly, I now have DTS-HD MSTR.

Thanks Anssi for your great work!
Thanks to any one who contributed to it.
I can't believe I've struggled for so many months and only 8 lines of kernel code fix it.

Hail ALSA and hail Linux :), I now have the perfect media center


Le 6 sept. 2013 à 10:43, Ashecrow a écrit :

> Hi guys,
> Anssi, thank you very much for your work! I'll test the patch asap and I'll keep you posted.
> 
> Takashi, where can I get patched kernel sources, or on which branch do I apply the patch to?
> 
> Thanks
> Etienne
> 
> Le 2 sept. 2013 à 15:06, Takashi Iwai <tiwai at suse.de> a écrit :
> 
>> At Sun,  1 Sep 2013 14:36:47 +0300,
>> Anssi Hannula wrote:
>>> 
>>> hdmi_channel_allocation() tries to find a HDMI channel allocation that
>>> matches the number channels in the playback stream and contains only
>>> speakers that the HDMI sink has reported as available via EDID. If no
>>> such allocation is found, 0 (stereo audio) is used.
>>> 
>>> Using CA 0 causes the audio causes the sink to discard everything except
>>> the first two channels (front left and front right).
>>> 
>>> However, the sink may be capable of receiving more channels than it has
>>> speakers (and then perform downmix or discard the extra channels), in
>>> which case it is preferable to use a CA that contains extra channels
>>> than to use CA 0 which discards all the non-stereo channels.
>>> 
>>> Additionally, it seems that HBR (HD) passthrough output does not work on
>>> Intel HDMI codecs when CA is set to 0 (possibly the codec zeroes
>>> channels not present in CA). This happens with all receivers that report
>>> a 5.1 speaker mask since a HBR stream is carried on 8 channels to the
>>> codec.
>>> 
>>> Add a fallback in the CA selection so that the CA channel count at least
>>> matches the stream channel count, even if the stream contains channels
>>> not present in the sink speaker descriptor.
>>> 
>>> Thanks to GrimGriefer at OpenELEC forums for discovering that changing
>>> the sink speaker mask allowed HBR output.
>>> 
>>> Reported-by: GrimGriefer
>>> Reported-by: Ashecrow
>>> Reported-by: Frank Zafka <kafkaesque1978 at gmail.com>
>>> Reported-by: Peter Frühberger <fritsch at xbmc.org>
>>> Signed-off-by: Anssi Hannula <anssi.hannula at iki.fi>
>>> Cc: <stable at vger.kernel.org>
>>> ---
>>> 
>>> Hopefully this fixes HBR (HD passthrough) for the remaining Intel users
>>> who were still experiencing problems.
>> 
>> Thanks, I applied the patch now.
>> 
>> 
>>> BTW, the hdmi_channel_allocation() logic seems also otherwise somewhat
>>> suspect to me. Shouldn't we always select an allocation matching ALSA
>>> channel mapping, instead of re-assigning channels received from
>>> userspace "randomly" to sink speakers (in case of unusual sink speaker
>>> mask)?
>> 
>> If per_pin->chmap_set is set beforehand,
>> hdmi_manual_channel_allocation() is called instead.  So it should be
>> fine.
>> 
>> 
>> Takashi
>> 
>>> Anyway, I let it be for now at least.
>>> 
>>> 
>>> sound/pci/hda/patch_hdmi.c | 11 +++++++++++
>>> 1 file changed, 11 insertions(+)
>>> 
>>> diff --git a/sound/pci/hda/patch_hdmi.c b/sound/pci/hda/patch_hdmi.c
>>> index 030ca86..354fc55 100644
>>> --- a/sound/pci/hda/patch_hdmi.c
>>> +++ b/sound/pci/hda/patch_hdmi.c
>>> @@ -551,6 +551,17 @@ static int hdmi_channel_allocation(struct hdmi_eld *eld, int channels)
>>>      }
>>>  }
>>> 
>>> +    if (!ca) {
>>> +        /* if there was no match, select the regular ALSA channel
>>> +         * allocation with the matching number of channels */
>>> +        for (i = 0; i < ARRAY_SIZE(channel_allocations); i++) {
>>> +            if (channels == channel_allocations[i].channels) {
>>> +                ca = channel_allocations[i].ca_index;
>>> +                break;
>>> +            }
>>> +        }
>>> +    }
>>> +
>>>  snd_print_channel_allocation(eld->info.spk_alloc, buf, sizeof(buf));
>>>  snd_printdd("HDMI: select CA 0x%x for %d-channel allocation: %s\n",
>>>          ca, channels, buf);
>>> -- 
>>> 1.8.1.5
>>>