Alsa support for Realtek ALC850

Alsa support for Realtek ALC850

[Dirk Jagdmann]

Hello developers,

I recently purchased an ASUS P4P800-E mainboard which features i865 
chipset with an Realtek ALC850 AC'97 Codec. This codec is recognized by 
the i8x0 drivers (I tested this with Alsa 1.0.8) as an 6 channel device. 
However this chip supports 8 channels, but this is not 
supported/recognized by Alsa currently. I had a quick look into the i8x0 
sources, but did not find the correct spot, where to patch the source to 
support 8 channels. I ask you for assistance on this subject. Please 
tell me which contents of /proc or /sys you'd like to see or please give 
me some pointers into the source.

-- 
---> doj / cubic
----> http://cubic.org/~doj
-----> http://llg.cubic.org


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Re: Alsa support for Realtek ALC850

[Clemens Ladisch]

Dirk Jagdmann wrote:
> I recently purchased an ASUS P4P800-E mainboard which features i865
> chipset with an Realtek ALC850 AC'97 Codec. This codec is recognized by
> the i8x0 drivers (I tested this with Alsa 1.0.8) as an 6 channel device.
> However this chip supports 8 channels, but this is not
> supported/recognized by Alsa currently. I had a quick look into the i8x0
> sources, but did not find the correct spot, where to patch the source to
> support 8 channels.

The ICH5 southbridge does not support 8-channel streams.  However, it
would be possible to combine the standard 6-channel device and the
SPDIF device into an 8-channel device, if the codec expects the last
two channels on the AC'97 slots usually used for SPDIF.

Put the following into your ~/.asoundrc file:

pcm.ch123456 {
	type hw
	card 0
	device 0
}

pcm.ch78 {
	type hw
	card 0
	device 4
}

pcm.eight {
	type plug
	slave.pcm {
		type multi
		slaves.a {
			pcm ch123456
			channels 6
		}
		slaves.b {
			pcm ch78
			channels 2
		}
		bindings [
			{ slave a channel 0 }
			{ slave a channel 1 }
			{ slave a channel 2 }
			{ slave a channel 3 }
			{ slave a channel 4 }
			{ slave a channel 5 }
			{ slave b channel 0 }
			{ slave b channel 1 }
		]
	}
}


However, it might be possible that the chip needs some configuration
bit to be set that the driver doesn't yet know about.


HTH
Clemens



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Re: Alsa support for Realtek ALC850

[Dirk Jagdmann]

> The ICH5 southbridge does not support 8-channel streams.  However, it

My manual says it's an ICH5R. The board is pretty new. The datasheet for 
the ALC850 codec claims it can do 8 channel sound. Thus I have just made 
a check (under windows) by playing back an 8 channel wav. All eight 
channels are clearly present on the 4 stereo 3.5mm (onboard jacks). 
Further the S/PDIF connector is the same as the first two channels 
(front l/r). So I conclude I have a true 8 channel codec.

> However, it might be possible that the chip needs some configuration
> bit to be set that the driver doesn't yet know about.

I say yes.

So, how can I help in supporting this chip.

Website for ALC850: 
http://www.realtek.com.tw/products/products1-2.aspx?modelid=2003101

-- 
---> doj / cubic
----> http://cubic.org/~doj
-----> http://llg.cubic.org


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Re: Alsa support for Realtek ALC850

[Dirk Jagdmann]

I should have mentioned that this setup is currently recognized and 
working as a 6 channel device with Alsa. The first 6 channels work 
flawlessly, but channel 7+8 can not be accessed.

-- 
---> doj / cubic
----> http://cubic.org/~doj
-----> http://llg.cubic.org


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Re: Alsa support for Realtek ALC850

[Takashi Iwai]

At Tue, 19 Apr 2005 10:39:15 +0200,
Dirk Jagdmann wrote:
> 
> I should have mentioned that this setup is currently recognized and 
> working as a 6 channel device with Alsa. The first 6 channels work 
> flawlessly, but channel 7+8 can not be accessed.

According to the spec, we'll need to flip the register 0x6a bit 9/10
and adjust Aux volume, at least.


Takashi


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