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

From: Dmitry Osipenko <digetx@gmail.com>
To: Ben Dooks <ben.dooks@codethink.co.uk>
Cc: linux-kernel@lists.codethink.co.uk, alsa-devel@alsa-project.org,
	Liam Girdwood <lgirdwood@gmail.com>,
	Takashi Iwai <tiwai@suse.com>, Mark Brown <broonie@kernel.org>,
	Thierry Reding <thierry.reding@gmail.com>,
	Edward Cragg <edward.cragg@codethink.co.uk>,
	linux-tegra@vger.kernel.org, Jon Hunter <jonathanh@nvidia.com>
Subject: Re: [alsa-devel] [Linux-kernel] [PATCH v5 2/7] ASoC: tegra: Allow 24bit and 32bit samples
Date: Fri, 24 Jan 2020 01:11:23 +0300	[thread overview]
Message-ID: <76a6a818-ab60-45eb-a85e-fa3090266d6f@gmail.com> (raw)
In-Reply-To: <9b3a0cdd-34c7-ecb4-4a26-268fd4a63041@codethink.co.uk>

24.01.2020 00:59, Ben Dooks пишет:
> On 23/01/2020 19:38, Ben Dooks wrote:
>> 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 did a quick test with the following:
>>
>>   sox -n -b 16 -c 2 -r 44100 /tmp/tmp.wav  synth sine 500 vol 0.5
>>   sox -n -b 24 -c 2 -r 44100 /tmp/tmp.wav  synth sine 500 vol 0.5
>>   sox -n -b 32 -c 2 -r 44100 /tmp/tmp.wav  synth sine 500 vol 0.5
>>
>> The 16 and 32 work fine, the 24 is showing a playback output freq
>> of 440Hz instead of 500Hz... this suggests the clock is off, or there
>> is something else weird going on...
>>
> 
> I should have checked pll_a_out0 rate, for 24bit 2ch, I get
> pll_a_out at which makes:
> 
> 11289600/(24*2*44100) = 5.3333333333
> 
> For some reason the PLL can't get a decent divisor for this.

Have you tried to adjust the predefined PLLA rate? Please see
tegra_clk_init_table in drivers/clk/tegra/clk-tegra30.c. Will be
interesting if it works with that.

Sowjanya said that the PLLA rate setup is going to be moved to the audio
driver [1], maybe that's what we already need for 24bit.

[1] https://lkml.org/lkml/2020/1/21/744
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