[alsa-devel] Wrong channel order with multichannel HDMI on MCP7A

[Takashi Iwai]

At Mon, 26 Jul 2010 11:14:17 +0200,
私 wrote:
> 
> At Sun, 25 Jul 2010 19:51:39 +0300,
> Anssi Hannula wrote:
> > 
> > Hi all!
> > 
> > I have a motherboard with NVIDIA MCP7A HDMI audio.
> > However, multichannel audio is not mapped properly into the HDMI order.
> > 
> > On 5.1, I get RL in FC, RR in LFE, FC in RL, LFE in RR.
> > 
> > Interestingly, this is not consistent with the ALSA channel order (FL FR RL RR 
> > FC LFE) being passed directly to HDMI (FL FR LFE FC RL RR). Instead it looks 
> > like there has been a waveformatex (FL FR FC LFE RL RR; windows?) => HDMI 
> > conversion instead of ALSA => HDMI.
> > 
> > Same happens for 7.1.
> > 
> > Is it possible to set the hardware to do an ALSA => HDMI conversion instead?
> > If not, we should manually compensate for this somewhere, right?
> 
> Does the patch below change anything?

Ah crap, it should be irrelevant.
Wei, don't MCP 7x chips support the channel mapping as MCP 89?


thanks,

Takashi


> > Somewhat relatedly, trying to output 4 channels results in silence only. 
> 
> Although 5.1/7.1 work?
> 
> > Trying to output 3 or 5 channels triggers a timeout with I/O error, with the 
> > following in the kernel log: "ALSA pcm_lib.c:1757: playback write error (DMA 
> > or IRQ trouble?)"
> 
> HD-audio doesn't support the odd number of channels in general, so
> they should be played as 4 or 6 channels.  But, it looks like
> something wrong in the setup...
> 
> 
> thanks,
> 
> Takashi
> 
> ---
> diff --git a/sound/pci/hda/patch_nvhdmi.c b/sound/pci/hda/patch_nvhdmi.c
> index 3c10c0b..7355c60 100644
> --- a/sound/pci/hda/patch_nvhdmi.c
> +++ b/sound/pci/hda/patch_nvhdmi.c
> @@ -511,6 +511,8 @@ static int patch_nvhdmi_8ch_7x(struct hda_codec *codec)
>  
>  	codec->patch_ops = nvhdmi_patch_ops_8ch_7x;
>  
> +	init_channel_allocations();
> +
>  	return 0;
>  }
>