drm/i2c: tda998x: improve programming of audio divisor (7dad3740) · Commits · 戴 / test

drivers/gpu/drm/i2c/tda998x_drv.c

+28 −16

Original line number	Diff line number	Diff line
		@@ -865,6 +865,32 @@ tda998x_write_avi(struct tda998x_priv priv, const struct drm_display_mode mode

		/* Audio support */

		/*
		* The audio clock divisor register controls a divider producing Audio_Clk_Out
		* from SERclk by dividing it by 2^n where 0 <= n <= 5. We don't know what
		* Audio_Clk_Out or SERclk are. We guess SERclk is the same as TMDS clock.
		*
		* It seems that Audio_Clk_Out must be the smallest value that is greater
		* than 128*fs, otherwise audio does not function. There is some suggestion
		* that 126*fs is a better value.
		*/
		static u8 tda998x_get_adiv(struct tda998x_priv *priv, unsigned int fs)
		{
		unsigned long min_audio_clk = fs * 128;
		unsigned long ser_clk = priv->tmds_clock * 1000;
		u8 adiv;

		for (adiv = AUDIO_DIV_SERCLK_32; adiv != AUDIO_DIV_SERCLK_1; adiv--)
		if (ser_clk > min_audio_clk << adiv)
		break;

		dev_dbg(&priv->hdmi->dev,
		"ser_clk=%luHz fs=%uHz min_aclk=%luHz adiv=%d\n",
		ser_clk, fs, min_audio_clk, adiv);

		return adiv;
		}

		static void tda998x_audio_mute(struct tda998x_priv *priv, bool on)
		{
		if (on) {
		@@ -882,6 +908,8 @@ static int tda998x_configure_audio(struct tda998x_priv *priv,
		u8 buf[6], clksel_aip, clksel_fs, cts_n, adiv;
		u32 n;

		adiv = tda998x_get_adiv(priv, settings->params.sample_rate);

		/* Enable audio ports */
		reg_write(priv, REG_ENA_AP, settings->params.config);

		@@ -926,22 +954,6 @@ static int tda998x_configure_audio(struct tda998x_priv *priv,
		reg_clear(priv, REG_AIP_CNTRL_0, AIP_CNTRL_0_LAYOUT \|
		AIP_CNTRL_0_ACR_MAN); /* auto CTS */
		reg_write(priv, REG_CTS_N, cts_n);

		/*
		* Audio input somehow depends on HDMI line rate which is
		* related to pixclk. Testing showed that modes with pixclk
		* >100MHz need a larger divider while <40MHz need the default.
		* There is no detailed info in the datasheet, so we just
		* assume 100MHz requires larger divider.
		*/
		adiv = AUDIO_DIV_SERCLK_8;
		if (priv->tmds_clock > 100000)
		adiv++; /* AUDIO_DIV_SERCLK_16 */

		/* S/PDIF asks for a larger divider */
		if (settings->params.format == AFMT_SPDIF)
		adiv++; /* AUDIO_DIV_SERCLK_16 or _32 */

		reg_write(priv, REG_AUDIO_DIV, adiv);

		/*

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