[alsa-devel] ALSA Multichannel through HDMI

John Ettedgui john.ettedgui at gmail.com
Fri Nov 26 02:08:49 CET 2010

On Thu, Nov 25, 2010 at 4:59 PM, Anssi Hannula <anssi.hannula at iki.fi> wrote:
> On 26.11.2010 02:53, John Ettedgui wrote:
>> On Thu, Nov 25, 2010 at 3:34 PM, John Ettedgui <john.ettedgui at gmail.com> wrote:
>>> On Thu, Nov 25, 2010 at 3:15 PM, Anssi Hannula <anssi.hannula at iki.fi> wrote:
>>>> On 26.11.2010 01:11, John Ettedgui wrote:
>>>>> On Thu, Nov 25, 2010 at 2:58 PM, Anssi Hannula <anssi.hannula at iki.fi> wrote:
>>>>>> On 26.11.2010 00:42, John Ettedgui wrote:
>>>>>>> On Thu, Nov 25, 2010 at 11:19 AM, Anssi Hannula <anssi.hannula at iki.fi> wrote:
>>>>>>>> On 25.11.2010 14:21, John Ettedgui wrote:
>>>>>>>>> On Thu, Nov 25, 2010 at 3:40 AM, Anssi Hannula <anssi.hannula at iki.fi> wrote:
>>>>>>>>>> On 25.11.2010 13:09, John Ettedgui wrote:
>>>>>>>>>>> On Thu, Nov 25, 2010 at 2:49 AM, Anssi Hannula <anssi.hannula at iki.fi> wrote:
>>>>>>>>>>>> On 25.11.2010 06:12, John Ettedgui wrote:
>>>>>>>>>>>>> I'm actually trying to get a 5.1 setup working without passthrough, if
>>>>>>>>>>>>> I use mplayer with passthrough my receiver behaves just fine, but I am
>>>>>>>>>>>>> trying to send the 6 channels from the computer.
>>>>>>>>>>>>> I was actually told that the current ALSA driver for radeon's hdmi
>>>>>>>>>>>>> does not support more than 2 channels, and that would explain why I'm
>>>>>>>>>>>>> getting this behavior. Is that true though?
>>>>>>>>>>>> Yes.
>>>>>>>>>>>> However, strangely your log output seems to show the intel's hdmi parser
>>>>>>>>>>>> being used instead:
>>>>>>>>>>>>> ALSA sound/pci/hda/patch_intelhdmi.c:842: hdmi_setup_stream: NID=0x2,
>>>>>>>>>>>>> stream=0x1, new-format=0x11
>>>>>>>>>>>> Were you just trying some patch at the time?
>>>>>>>>>>> yes Wu gave me a patch to try against the kernel, I'm guessing this is
>>>>>>>>>>> the reason you see something unexpected.
>>>>>>>>>> Did 6 channels work with that patch? (possibly with a wrong channel order)
>>>>>>>>> Not any better as far as I remember.
>>>>>>>> OK. Did 2 channel audio continue to work with it?
>>>>>>>> If you are not sure, here's the patch doing the same thing against
>>>>>>>> current alsa driver:
>>>>>>>> http://stuff.onse.fi/0001-ALSA-hda-Use-generic-HDMI-code-for-ATI-HDMI-codecs.patch
>>>>>>>> Confirming that would help (it would allow to switch the ATI chip to use
>>>>>>>> the generic parser instead of the ATI-specific one), though not with the
>>>>>>>> multichannel issue (see below).
>>>>>>>> [...]
>>>>>>>>>>> Since I just moved to jack/rca cables I'm in no hurry anymore, but is
>>>>>>>>>>> there any reason why the driver cannot work with more than 2 channels?
>>>>>>>>>> I don't really know (it is simply not implemented).
>>>>>>>>> Alright.
>>>>>>>>>>> Anything I could do to help with that?
>>>>>>>>>> Possibly. But see above, so that we won't try the same things you
>>>>>>>>>> already tried :)
>>>>>>>>> Sure :)
>>>>>>>> Looking again at the the alsa info output you provided, I don't think I
>>>>>>>> have any great ideas. It looks like the chip simply reports that it
>>>>>>>> supports a maximum of 2 channels.
>>>>>>>> One option could be hardcoding "chans = 8;" in generic_hdmi_build_pcms()
>>>>>>>> in sound/pci/hda/patch_hdmi.c (assuming you have the above patch and 2
>>>>>>>> channel audio works with it). However, I find it rather unlikely that it
>>>>>>>> would make any difference.
>>>>>>>> --
>>>>>>>> Anssi Hannula
>>>>>>> Anssi,
>>>>>>> the patch fails on my kernel, I cannot find the hda_codec_preset
>>>>>>> manually in there either.
>>>>>>> Did you want me to try that against a 2.6.37 rc instead of a 2.6.36?
>>>>>> For 2.6.36 I think you can just use your earlier patch.
>>>>>> Note that on that kernel generic_hdmi_build_pcms() is
>>>>>> intel_hdmi_build_pcms() in patch_intelhdmi.c.
>>>>> ok
>>>>>> BTW, I've just been informed by another ATI user that his card was
>>>>>> actually stereo-only, while he thought earlier it was multichannel
>>>>>> capable. So, are you sure your card is a multichannel one?
>>>>>> (if not, it would explain why the card says it is not)
>>>>>> --
>>>>>> Anssi Hannula
>>>>> Yes, it works fine in Window  so I believe the hardware part is good.
>>>> And you are sure it is multichannel PCM, and not e.g. multichannel DTS
>>>> or multichannel AC-3 with on-the-fly compression, which are possible
>>>> with stereo hdmi as well?
>>>> Just making sure :)
>>>> --
>>>> Anssi Hannula
>>> Well, I have not super tested it, but the reason I believe it is is
>>> simple, when I use passthrough my receiver says Dolby digital or
>>> something like that, but in Windows just going around or playing games
>>> it says Multichannel.
> Sounds ok then.
>>> I'll get the patch applied in a few minutes, I was running out of
>>> memory and my system was getting really slow... :)
>> I am not sure if I did it right but now I don't even get hdmi sound
>> working anymore.
>> It is not listed in aplay-l, and dmesg gives me this:
>> [drm:radeon_dvi_detect] *ERROR* HDMI Type A-1: probed a monitor but
>> no|invalid EDID
>> I've attached the patch I used, since I could not used the previous
>> one I had to hack it, maybe I broke something?
>> (I have not set channels to 8 yet, just changed the parser)
> The patch looks ok. The above error message is weird, as it comes from
> the display driver which should not be affected by the patch at all.
> I'll look at the code later (tomorrow maybe). Until then I'd advise you
> to retry without the patch and with the patch again, just to make sure
> this is not some unrelated issue...
> Also, post the whole dmesg when it works (2 channel, without patch), and
> when it doesn't (with patch).
> --
> Anssi Hannula
Following your message I restarted my computer and that error was
gone, yet there is still nothing display in aplay -l / aplay -L about
hdmi anymore.
I'll go back to my non patched kernel and see what it does.

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