Hi Minhong,

 

Please find answers to your questions below:

1. Is UAC3 enabled by default (said master codes)?

    Yes. UAC3 support is available in kernel by default. But, you need UAC3-compliant audio device to get this feature.

2. If I would like to make it disabled, what is the suggested way?

2.1 from something like menuconfig to NOT build the features from Kernel?

There is no menuconfig to disable this feature.

2.2 after booting into Celadon, any entry to disable this feature?

You can switch to backward-compatible UAC1/UAC2 configuration by writing 1 into bConfigurationValue sysfs.

echo 1 > /sys/bus/usb/devices/<n-n>bConfigurationValue

where n-n is the hub number and port number where the USB device is enumerated. You can get this value from dmesg.

And you will need to change the file permission for this sysfs to write into it,

 

Is your audio device having more than one configuration? In that case, the UAC3 patch caused an issue which makes the last configuration get selected for non-UAC3 compliant device.

You can cherry-pick this patch to get that fixed. This patch is available upstream:

https://lore.kernel.org/patchwork/patch/1029221/

 

Please let us know if you have any more questions.

 

Thanks,

Saranya

 

 

From: Celadon [mailto:celadon-bounces@lists.01.org] On Behalf Of Zhang, Yanmin
Sent: Thursday, July 18, 2019 7:56 AM
To: Ming-Hong Wu <minhong.wu@gmail.com>; celadon@lists.01.org
Subject: Re: [01.org Celadon] Enable/Disable UAC3

 

+Balaji.

 

@Minghong, why do you want to disable UAC3? Does it cause any issue?

 

Yanmin

 

From: Celadon [mailto:celadon-bounces@lists.01.org] On Behalf Of Ming-Hong Wu
Sent: Thursday, July 18, 2019 12:13 AM
To: celadon@lists.01.org
Subject: [01.org Celadon] Enable/Disable UAC3

 

Hi,

 

I checked with the tutorial,

https://01.org/projectceladon/documentation/tutorials/enabling-uac3 

 

I've questions as below after reading that,

 

1. Is UAC3 enabled by default (said master codes)?

 

2. If I would like to make it disabled, what is the suggested way?

2.1 from something like menuconfig to NOT build the features from Kernel?

2.2 after booting into Celadon, any entry to disable this feature?

 

 

--

Sincerely,

minhong