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From: Jon Hunter <jonathanh@nvidia.com>
To: Mark Brown <broonie@kernel.org>, Sameer Pujar <spujar@nvidia.com>
Cc: <perex@perex.cz>, <tiwai@suse.com>, <robh+dt@kernel.org>,
	<lgirdwood@gmail.com>, <thierry.reding@gmail.com>,
	<digetx@gmail.com>, <alsa-devel@alsa-project.org>,
	<devicetree@vger.kernel.org>, <linux-tegra@vger.kernel.org>,
	<linux-kernel@vger.kernel.org>, <sharadg@nvidia.com>,
	<mkumard@nvidia.com>, <viswanathl@nvidia.com>,
	<rlokhande@nvidia.com>, <dramesh@nvidia.com>,
	<atalambedu@nvidia.com>
Subject: Re: [PATCH v3 03/10] ASoC: tegra: add Tegra210 based DMIC driver
Date: Fri, 21 Feb 2020 14:31:05 +0000	[thread overview]
Message-ID: <316ce0d5-318d-0533-ef06-bd7e8672f893@nvidia.com> (raw)
In-Reply-To: <20200221130005.GD5546@sirena.org.uk>


On 21/02/2020 13:00, Mark Brown wrote:
> On Thu, Feb 20, 2020 at 12:04:45PM +0530, Sameer Pujar wrote:
> 
>> +++ b/sound/soc/tegra/tegra210_dmic.c
>> @@ -0,0 +1,515 @@
>> +// SPDX-License-Identifier: GPL-2.0-only
>> +/*
>> + * tegra210_dmic.c - Tegra210 DMIC driver
>> + *
>> + * Copyright (c) 2020 NVIDIA CORPORATION.  All rights reserved.
> 
> Please make the entire comment a C++ one so things look more
> intentional.
> 
>> +	/* Below enables all filters - DCR, LP and SC */
>> +	{ TEGRA210_DMIC_DBG_CTRL, 0xe },
> 
> So this isn't the hardware default?
> 
>> +	srate = params_rate(params);
>> +	if (dmic->srate_override)
>> +		srate = dmic->srate_override;
> 
> How does this work for userspace?  If we just ignore the sample rate we
> were asked for I'd expect that the application would get upset.

Tegra has a hardware sample rate converter (though driver not yet
upstream or part of this initial series) and if using the sample-rate
converter, then the actual rate captured by the DMIC interface could be
different from the resulting sample-rate.

So we want a way to indicate to the DMIC it is capturing at rate X,
while the resulting sample-rate is Y.

I am not sure if there is a better way to do this? Ideally, the DMIC
would query the rate from the upstream MUX it is connected to, but I am
not sure if there is a way to do that. So right now it is a manual
process and the user has to configure these which are not ideal.

Cheers
Jon

-- 
nvpublic

  reply	other threads:[~2020-02-21 14:31 UTC|newest]

Thread overview: 39+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-20  6:34 [PATCH v3 00/10] add ASoC components for AHUB Sameer Pujar
2020-02-20  6:34 ` [PATCH v3 01/10] dt-bindings: sound: tegra: add DT binding " Sameer Pujar
2020-02-21 12:39   ` Mark Brown
2020-02-26 16:02   ` Rob Herring
2020-02-20  6:34 ` [PATCH v3 02/10] ASoC: tegra: add support for CIF programming Sameer Pujar
2020-02-20 14:30   ` Jon Hunter
2020-02-21  5:27   ` Dmitry Osipenko
2020-02-20  6:34 ` [PATCH v3 03/10] ASoC: tegra: add Tegra210 based DMIC driver Sameer Pujar
2020-02-20 14:36   ` Jon Hunter
2020-02-21  5:53   ` Dmitry Osipenko
2020-02-21 13:00   ` Mark Brown
2020-02-21 14:31     ` Jon Hunter [this message]
2020-02-21 16:55       ` Mark Brown
2020-02-24 11:28         ` Jon Hunter
2020-02-24 11:44           ` Mark Brown
2020-02-24 12:29             ` Sameer Pujar
2020-02-24 13:18               ` Mark Brown
2020-02-28  7:30     ` Viswanath L
2020-02-20  6:34 ` [PATCH v3 04/10] ASoC: tegra: add Tegra210 based I2S driver Sameer Pujar
2020-02-20 14:45   ` Jon Hunter
2020-02-21 13:21   ` Mark Brown
2020-02-20  6:34 ` [PATCH v3 05/10] ASoC: tegra: add Tegra210 based AHUB driver Sameer Pujar
2020-02-20  6:51   ` Randy Dunlap
2020-02-20 15:08   ` Jon Hunter
2020-02-21 13:38   ` Mark Brown
2020-02-20  6:34 ` [PATCH v3 06/10] ASoC: tegra: add Tegra186 based DSPK driver Sameer Pujar
2020-02-20  6:53   ` Randy Dunlap
2020-02-20 15:10   ` Jon Hunter
2020-02-20  6:34 ` [PATCH v3 07/10] ASoC: tegra: add Tegra210 based ADMAIF driver Sameer Pujar
2020-02-20  6:55   ` Randy Dunlap
2020-02-20 15:16   ` Jon Hunter
2020-02-21  6:08   ` Dmitry Osipenko
2020-02-20  6:34 ` [PATCH v3 08/10] arm64: tegra: add AHUB components for few Tegra chips Sameer Pujar
2020-02-20 14:49   ` Jon Hunter
2020-02-20  6:34 ` [PATCH v3 09/10] arm64: tegra: enable AHUB modules " Sameer Pujar
2020-02-20 14:52   ` Jon Hunter
2020-02-20  6:34 ` [PATCH v3 10/10] arm64: defconfig: enable AHUB components for Tegra210 and later Sameer Pujar
2020-02-20 14:52   ` Jon Hunter
2020-02-21  5:44   ` Dmitry Osipenko

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