[alsa-devel] [PATCH] add native DSD support for XMOS based DACs.

[Clemens Ladisch]

Jurgen Kramer wrote:
> On Fri, 2014-09-05 at 11:36 +0200, Clemens Ladisch wrote:
>> Jurgen Kramer wrote:
>>> Add quirk for XMOS based DACs for native DSD playback support using the new DSD_U32_LE sample
>>> format. Works for all DAC vendors which use XMOS as idVendor. E.g. iFi Audio
>>> with their micro iDSD and nano iDSD.
>>>
>>> +++ b/sound/usb/quirks.c
>>> +	/* XMOS based DACs, e.g. iFi Audio micro/nano iDSD */
>>> +	if (le16_to_cpu(chip->dev->descriptor.idVendor) == 0x20b1) {
>>> +		switch (fp->altsetting) {
>>> +		case 2:
>>> +			return SNDRV_PCM_FMTBIT_DSD_U32_LE;
>>
>> Can you confirm that all XMOS devices ever built will have DSD on that
>> alternate setting?
>
> No, I can not. Most newer implementations will use alt setting 2 for
> native DSD support.

But it's possible to have other XMOS-based devices that use multiple
alternate settings for PCM.

> My first version also used idProduct to only target iFi devices. If
> this is required, I'll rework my patch.

I guess there isn't any property of the descriptors to distinguish DoP
from PCM?  How does the generic Windows driver know which alternate
settings are DoP?


Regards,
Clemens