[alsa-devel] [PATCH RFC 4/5] ASoC: davinci-mcasp: Get rid of bclk_lrclk_ratio in private data

[Jyri Sarha]

On 09/09/15 21:27, Jyri Sarha wrote:
> The slot_width is for essentially same thing. Instead of storing
> bclk_lrclk_ratio, just store the slot_width. Comments has been updated
> accordingly and some variable names changed to more descriptive.
>
> Signed-off-by: Jyri Sarha <jsarha at ti.com>
> ---
>   sound/soc/davinci/davinci-mcasp.c | 56 ++++++++++++++++++++++-----------------
>   1 file changed, 31 insertions(+), 25 deletions(-)
>
> diff --git a/sound/soc/davinci/davinci-mcasp.c b/sound/soc/davinci/davinci-mcasp.c
> index de1e3a8..25ff1fc 100644
> --- a/sound/soc/davinci/davinci-mcasp.c
> +++ b/sound/soc/davinci/davinci-mcasp.c
> @@ -87,7 +87,6 @@ struct davinci_mcasp {
>   	u8	*serial_dir;
>   	u8	version;
>   	u8	bclk_div;
> -	u16	bclk_lrclk_ratio;
>   	int	streams;
>   	u32	irq_request[2];
>   	int	dma_request[2];
> @@ -558,8 +557,21 @@ static int __davinci_mcasp_set_clkdiv(struct snd_soc_dai *dai, int div_id,
>   			mcasp->bclk_div = div;
>   		break;
>
> -	case 2:		/* BCLK/LRCLK ratio */
> -		mcasp->bclk_lrclk_ratio = div;
> +	case 2:	/*
> +		 * BCLK/LRCLK ratio descries how many bit-clock cycles
> +		 * fit into one frame. The clock ratio is given for a
> +		 * full period of data (for I2S format both left and
> +		 * right channels), so it has to be divided by number
> +		 * of tdm-slots (for I2S - divided by 2).
> +		 * Instead of storing this ratio, we calculate a new
> +		 * tdm_slot width by dividing the the ratio by the
> +		 * number of configured tdm slots.
> +		 */
> +		mcasp->slot_width = div / mcasp->tdm_slots;
> +		if (div % mcasp->tdm_slots)
> +			dev_warn(mcasp->dev,
> +				 "%s(): BCLK/LRCLK %d is not divisible by %d tdm slots",
> +				 div, mcasp->tdm_slots);

Oops, there is a __func__ missing here.

>   		break;
>
>   	default:
> @@ -682,11 +694,13 @@ static int davinci_mcasp_set_tdm_slot(struct snd_soc_dai *dai,
>   }
>
>   static int davinci_config_channel_size(struct davinci_mcasp *mcasp,
> -				       int word_length)
> +				       int sample_width)
>   {
>   	u32 fmt;
> -	u32 tx_rotate = (word_length / 4) & 0x7;
> -	u32 mask = (1ULL << word_length) - 1;
> +	u32 tx_rotate = (sample_width / 4) & 0x7;
> +	u32 mask = (1ULL << sample_width) - 1;
> +	u32 slot_width = sample_width;
> +
>   	/*
>   	 * For captured data we should not rotate, inversion and masking is
>   	 * enoguh to get the data to the right position:
> @@ -699,31 +713,23 @@ static int davinci_config_channel_size(struct davinci_mcasp *mcasp,
>   	u32 rx_rotate = 0;
>
>   	/*
> -	 * if s BCLK-to-LRCLK ratio has been configured via the set_clkdiv()
> -	 * callback, take it into account here. That allows us to for example
> -	 * send 32 bits per channel to the codec, while only 16 of them carry
> -	 * audio payload.
> -	 * The clock ratio is given for a full period of data (for I2S format
> -	 * both left and right channels), so it has to be divided by number of
> -	 * tdm-slots (for I2S - divided by 2).
> +	 * Setting the tdm slot width either with set_clkdiv() or
> +	 * set_tdm_slot() allows us to for example send 32 bits per
> +	 * channel to the codec, while only 16 of them carry audio
> +	 * payload.
>   	 */
> -	if (mcasp->bclk_lrclk_ratio) {
> -		u32 slot_length = mcasp->bclk_lrclk_ratio / mcasp->tdm_slots;
> -
> +	if (mcasp->slot_width) {
>   		/*
> -		 * When we have more bclk then it is needed for the data, we
> -		 * need to use the rotation to move the received samples to have
> -		 * correct alignment.
> +		 * When we have more bclk then it is needed for the
> +		 * data, we need to use the rotation to move the
> +		 * received samples to have correct alignment.
>   		 */
> -		rx_rotate = (slot_length - word_length) / 4;
> -		word_length = slot_length;
> -	} else if (mcasp->slot_width) {
> -		rx_rotate = (mcasp->slot_width - word_length) / 4;
> -		word_length = mcasp->slot_width;
> +		slot_width = mcasp->slot_width;
> +		rx_rotate = (slot_width - sample_width) / 4;
>   	}
>
>   	/* mapping of the XSSZ bit-field as described in the datasheet */
> -	fmt = (word_length >> 1) - 1;
> +	fmt = (slot_width >> 1) - 1;
>
>   	if (mcasp->op_mode != DAVINCI_MCASP_DIT_MODE) {
>   		mcasp_mod_bits(mcasp, DAVINCI_MCASP_RXFMT_REG, RXSSZ(fmt),
>