[alsa-devel] [Linux-kernel] [PATCH v5 2/7] ASoC: tegra: Allow 24bit and 32bit samples

[Jon Hunter]

On 07/01/2020 01:39, Dmitry Osipenko wrote:
> 06.01.2020 22:00, Ben Dooks пишет:
>> On 05/01/2020 10:53, Ben Dooks wrote:
>>>
>>>
>>> On 2020-01-05 01:48, Dmitry Osipenko wrote:
>>>> 05.01.2020 03:04, Ben Dooks пишет:
>>>>> [snip]
>>>>>
>>>>> I've just gone through testing.
>>>>>
>>>>> Some simple data tests show 16 and 32-bits work.
>>>>>
>>>>> The 24 bit case seems to be weird, it looks like the 24-bit expects
>>>>> 24 bit samples in 32 bit words. I can't see any packing options to
>>>>> do 24 bit in 24 bit, so we may have to remove 24 bit sample support
>>>>> (which is a shame)
>>>>>
>>>>> My preference is to remove the 24-bit support and keep the 32 bit in.
>>>>>
>>>>
>>>> Interesting.. Jon, could you please confirm that 24bit format isn't
>>>> usable on T30?
>>>
>>> If there is an option of 24 packed into 32, then I think that would work.
>>>
>>> I can try testing that with raw data on Monday.
>>
>> I need to check some things, I assumed 24 was 24 packed bits, it looks
>> like the default is 24 in 32 bits so we may be ok. However I need to
>> re-write my test case which assumed it was 24bits in 3 bytes (S24_3LE).
>>
>> I'll follow up later,
> 
> Okay, the S24_3LE isn't supported by RT5640 codec in my case. I briefly
> looked through the TRM doc and got impression that AHUB could re-pack
> data stream into something that codec supports, but maybe it's a wrong
> impression.

I chatted with Sameer about this, so yes the AHUB can repack, but there
is a problem with S24_LE where if we try to extract 24-bits we actually
get the upper 24-bits and not the lower LSBs in the 32-bit data element.
So actually we don't support S24_LE.

Ben do you need 24-bit support or 32-bit or both?

Jon

-- 
nvpublic