On Mon, 27 Jun 2022 12:00:34 +0200, Egor Vorontsov wrote:

Fiero SC-01 is a USB sound card with two mono inputs and a single stereo output. The inputs are composed into a single stereo stream.

The device uses a vendor-provided driver on Windows and does not work at all without it. The driver mostly provides ASIO functionality, but also alters the way the sound card is queried for sample rates and clocks.

ALSA queries those failing with an EPIPE (same as Windows 10 does). Presumably, the vendor-provided driver does not query it at all, simply matching by VID:PID. Thus, I consider this a buggy firmware and adhere to a set of fixed endpoint quirks instead.

The soundcard has an internal clock. Implicit feedback mode is required for the playback.

I have updated my device to v1.1.0 from a Windows 10 VM using a vendor- provided binary prior to the development, hoping for it to just begin working. The device provides no obvious way to downgrade the firmware, and regardless, there's no binary available for v1.0.0 anyway.

Thus, I will be getting another unit to extend the patch with support for that. Expected to be a simple copy-paste of the existing one, though.

There were no previous reports of that device in context of Linux anywhere. Other issues have been reported though, but that's out of the scope.

Signed-off-by: Egor Vorontsov sdoregor@sdore.me

Thanks, now applied both patches.

Takashi