Re: [alsa-devel] [PATCH 1/8] ASoC: tegra: Add a TDM configuration callback

From: Jon Hunter <jonathanh@nvidia.com>
To: Ben Dooks <ben.dooks@codethink.co.uk>,
	<linux-tegra@vger.kernel.org>, <alsa-devel@alsa-project.org>,
	Jaroslav Kysela <perex@perex.cz>, Takashi Iwai <tiwai@suse.com>,
	Liam Girdwood <lgirdwood@gmail.com>,
	Mark Brown <broonie@kernel.org>,
	Thierry Reding <thierry.reding@gmail.com>
Cc: linux-kernel@lists.codethink.co.uk,
	Edward Cragg <edward.cragg@codethink.co.uk>
Subject: Re: [alsa-devel] [PATCH 1/8] ASoC: tegra: Add a TDM configuration callback
Date: Wed, 18 Sep 2019 09:42:19 +0100	[thread overview]
Message-ID: <7b21823a-86e8-d3de-10b5-e047a5e025ef@nvidia.com> (raw)
In-Reply-To: <20190917181233.534-2-ben.dooks@codethink.co.uk>

On 17/09/2019 19:12, Ben Dooks wrote:
> From: Edward Cragg <edward.cragg@codethink.co.uk>
> 
> Add a callback to configure TDM settings for the Tegra30 I2S ASoC 'platform'
> driver.
> 
> Signed-off-by: Edward Cragg <edward.cragg@codethink.co.uk>
> ---
>  sound/soc/tegra/tegra30_i2s.c | 34 ++++++++++++++++++++++++++++++++++
>  1 file changed, 34 insertions(+)
> 
> diff --git a/sound/soc/tegra/tegra30_i2s.c b/sound/soc/tegra/tegra30_i2s.c
> index ac6983c6bd72..d36b4662b420 100644
> --- a/sound/soc/tegra/tegra30_i2s.c
> +++ b/sound/soc/tegra/tegra30_i2s.c
> @@ -254,6 +254,39 @@ static int tegra30_i2s_trigger(struct snd_pcm_substream *substream, int cmd,
>  	return 0;
>  }
>  
> +/*
> + * Set up TDM
> + */
> +static int tegra30_i2s_set_tdm(struct snd_soc_dai *dai,
> +			       unsigned int tx_mask, unsigned int rx_mask,
> +			       int slots, int slot_width)
> +{
> +	struct tegra30_i2s *i2s = snd_soc_dai_get_drvdata(dai);
> +	unsigned int mask = 0, val = 0;
> +
> +	dev_info(dai->dev, "%s: setting TDM: tx_mask: 0x%08x rx_mask: 0x%08x "

dev_dbg() please. Also I don't think it is necessary to print both the
function name and 'setting TDM', the function name should be sufficient.

> +		 "slots: 0x%08x " "width: %d\n",

Why are there extra quotes here?

> +		 __func__, tx_mask, rx_mask, slots, slot_width)> +
> +	/* Set up slots and tx/rx masks */
> +	mask = TEGRA30_I2S_SLOT_CTRL_TOTAL_SLOTS_MASK |
> +	       TEGRA30_I2S_SLOT_CTRL_RX_SLOT_ENABLES_MASK |
> +	       TEGRA30_I2S_SLOT_CTRL_TX_SLOT_ENABLES_MASK;
> +
> +	val = (tx_mask << TEGRA30_I2S_SLOT_CTRL_TX_SLOT_ENABLES_SHIFT) |
> +	      (rx_mask << TEGRA30_I2S_SLOT_CTRL_RX_SLOT_ENABLES_SHIFT) |
> +	      ((slots - 1) << TEGRA30_I2S_SLOT_CTRL_TOTAL_SLOTS_SHIFT);
> +
> +	regmap_update_bits(i2s->regmap, TEGRA30_I2S_SLOT_CTRL, mask, val);
> +
> +	/* Set FSYNC width */
> +	regmap_update_bits(i2s->regmap, TEGRA30_I2S_CH_CTRL,
> +		TEGRA30_I2S_CH_CTRL_FSYNC_WIDTH_MASK,
> +		(slot_width - 1) << TEGRA30_I2S_CH_CTRL_FSYNC_WIDTH_SHIFT);

What happens if there is only one slot? The fsync will be the width of
the slot. Typically, TDM is used with DSP-A/B formats and although the
driver does not appear to program the fsync width, it probably should
during the tegra30_i2s_set_fmt() depending on the format used rather
than here.

Cheers
Jon

-- 
nvpublic
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