Re: [PATCH v7 9/9] drm/mediatek: hdmi: use helper function for N and CTS calculation

[Arnaud Pouliquen <arnaud.pouliquen@st.com>]

Hello Philipp,

FYI, i'm currently finalizing a new version of the helper function with
minor updates ( typo and code optimization), i should send it tomorrow.

Regards
Arnaud

On 04/20/2016 11:00 AM, Philipp Zabel wrote:
> Use the hdmi helper function [1] to calculate N and CTS.
> 
> [1] https://patchwork.kernel.org/patch/8091531/ ("video: hdmi: add helper
>     function for N and CTS")
> 
> Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
> ---
>  drivers/gpu/drm/mediatek/mtk_hdmi.c | 85 +++++++++----------------------------
>  1 file changed, 21 insertions(+), 64 deletions(-)
> 
> diff --git a/drivers/gpu/drm/mediatek/mtk_hdmi.c b/drivers/gpu/drm/mediatek/mtk_hdmi.c
> index 06e3811..da6edef 100644
> --- a/drivers/gpu/drm/mediatek/mtk_hdmi.c
> +++ b/drivers/gpu/drm/mediatek/mtk_hdmi.c
> @@ -656,65 +656,6 @@ static const struct hdmi_acr_n hdmi_rec_n_table[] = {
>  	{      0, {  4096,  6272,  6144 } }, /* all other TMDS clocks */
>  };
>  
> -/**
> - * hdmi_recommended_n() - Return N value recommended by HDMI specification
> - * @freq: audio sample rate in Hz
> - * @clock: rounded TMDS clock in kHz
> - */
> -static unsigned int hdmi_recommended_n(unsigned int freq, unsigned int clock)
> -{
> -	const struct hdmi_acr_n *recommended;
> -	unsigned int i;
> -
> -	for (i = 0; i < ARRAY_SIZE(hdmi_rec_n_table) - 1; i++) {
> -		if (clock == hdmi_rec_n_table[i].clock)
> -			break;
> -	}
> -	recommended = hdmi_rec_n_table + i;
> -
> -	switch (freq) {
> -	case 32000:
> -		return recommended->n[0];
> -	case 44100:
> -		return recommended->n[1];
> -	case 48000:
> -		return recommended->n[2];
> -	case 88200:
> -		return recommended->n[1] * 2;
> -	case 96000:
> -		return recommended->n[2] * 2;
> -	case 176400:
> -		return recommended->n[1] * 4;
> -	case 192000:
> -		return recommended->n[2] * 4;
> -	default:
> -		return (128 * freq) / 1000;
> -	}
> -}
> -
> -static unsigned int hdmi_mode_clock_to_hz(unsigned int clock)
> -{
> -	switch (clock) {
> -	case 25175:
> -		return 25174825;	/* 25.2/1.001 MHz */
> -	case 74176:
> -		return 74175824;	/* 74.25/1.001 MHz */
> -	case 148352:
> -		return 148351648;	/* 148.5/1.001 MHz */
> -	case 296703:
> -		return 296703297;	/* 297/1.001 MHz */
> -	default:
> -		return clock * 1000;
> -	}
> -}
> -
> -static unsigned int hdmi_expected_cts(unsigned int audio_sample_rate,
> -				      unsigned int tmds_clock, unsigned int n)
> -{
> -	return DIV_ROUND_CLOSEST_ULL((u64)hdmi_mode_clock_to_hz(tmds_clock) * n,
> -				     128 * audio_sample_rate);
> -}
> -
>  static void do_hdmi_hw_aud_set_ncts(struct mtk_hdmi *hdmi, unsigned int n,
>  				    unsigned int cts)
>  {
> @@ -739,21 +680,37 @@ static void do_hdmi_hw_aud_set_ncts(struct mtk_hdmi *hdmi, unsigned int n,
>  		mtk_hdmi_write(hdmi, GRL_NCTS, val[i]);
>  }
>  
> +static unsigned int hdmi_mode_clock_to_hz(unsigned int clock)
> +{
> +	switch (clock) {
> +	case 25175:
> +		return 25174825;	/* 25.2/1.001 MHz */
> +	case 74176:
> +		return 74175824;	/* 74.25/1.001 MHz */
> +	case 148352:
> +		return 148351648;	/* 148.5/1.001 MHz */
> +	case 296703:
> +		return 296703296;	/* 297/1.001 MHz */
> +	default:
> +		return clock * 1000;
> +	}
> +}
> +
>  static void mtk_hdmi_hw_aud_set_ncts(struct mtk_hdmi *hdmi,
>  				     unsigned int sample_rate,
>  				     unsigned int clock)
>  {
> -	unsigned int n, cts;
> +	struct hdmi_audio_n_cts n_cts;
>  
> -	n = hdmi_recommended_n(sample_rate, clock);
> -	cts = hdmi_expected_cts(sample_rate, clock, n);
> +	hdmi_audio_get_coherent_n_cts(sample_rate, hdmi_mode_clock_to_hz(clock),
> +				      &n_cts);
>  
>  	dev_dbg(hdmi->dev, "%s: sample_rate=%u, clock=%d, cts=%u, n=%u\n",
> -		__func__, sample_rate, clock, n, cts);
> +		__func__, sample_rate, clock, n_cts.cts, n_cts.n);
>  
>  	mtk_hdmi_mask(hdmi, DUMMY_304, AUDIO_I2S_NCTS_SEL_64,
>  		      AUDIO_I2S_NCTS_SEL);
> -	do_hdmi_hw_aud_set_ncts(hdmi, n, cts);
> +	do_hdmi_hw_aud_set_ncts(hdmi, n_cts.n, n_cts.cts);
>  }
>  
>  static u8 mtk_hdmi_aud_get_chnl_count(enum hdmi_aud_channel_type channel_type)
>