[4/4] drm: bridge: dw-hdmi: use new helper to get ACR values

Commit Message

Dmitry Baryshkov March 9, 2025, 8:13 a.m. UTC

From: Dmitry Baryshkov <[e-mail]>

Use drm_hdmi_acr_get_n_cts() helper instead of calculating N and CTS
values in the DW-HDMI driver.

Signed-off-by: Dmitry Baryshkov <[e-mail]>
---
 drivers/gpu/drm/bridge/synopsys/dw-hdmi.c | 90 +++----------------------------
 1 file changed, 8 insertions(+), 82 deletions(-)

Patch

diff --git a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
index 0890add5f7070f13fefad923526e92f516f06764..b8775e677233ca96c2d4a06fb5697aa3c0bd45c3 100644
--- a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
+++ b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
@@ -558,68 +558,6 @@  static void hdmi_set_cts_n(struct dw_hdmi *hdmi, unsigned int cts,
 	hdmi_writeb(hdmi, n & 0xff, HDMI_AUD_N1);
 }
 
-static unsigned int hdmi_compute_n(unsigned int freq, unsigned long pixel_clk)
-{
-	unsigned int n = (128 * freq) / 1000;
-	unsigned int mult = 1;
-
-	while (freq > 48000) {
-		mult *= 2;
-		freq /= 2;
-	}
-
-	switch (freq) {
-	case 32000:
-		if (pixel_clk == 25175000)
-			n = 4576;
-		else if (pixel_clk == 27027000)
-			n = 4096;
-		else if (pixel_clk == 74176000 || pixel_clk == 148352000)
-			n = 11648;
-		else if (pixel_clk == 297000000)
-			n = 3072;
-		else
-			n = 4096;
-		n *= mult;
-		break;
-
-	case 44100:
-		if (pixel_clk == 25175000)
-			n = 7007;
-		else if (pixel_clk == 74176000)
-			n = 17836;
-		else if (pixel_clk == 148352000)
-			n = 8918;
-		else if (pixel_clk == 297000000)
-			n = 4704;
-		else
-			n = 6272;
-		n *= mult;
-		break;
-
-	case 48000:
-		if (pixel_clk == 25175000)
-			n = 6864;
-		else if (pixel_clk == 27027000)
-			n = 6144;
-		else if (pixel_clk == 74176000)
-			n = 11648;
-		else if (pixel_clk == 148352000)
-			n = 5824;
-		else if (pixel_clk == 297000000)
-			n = 5120;
-		else
-			n = 6144;
-		n *= mult;
-		break;
-
-	default:
-		break;
-	}
-
-	return n;
-}
-
 /*
  * When transmitting IEC60958 linear PCM audio, these registers allow to
  * configure the channel status information of all the channel status
@@ -646,32 +584,20 @@  static void hdmi_set_clk_regenerator(struct dw_hdmi *hdmi,
 	unsigned long ftdms = pixel_clk;
 	unsigned int n, cts;
 	u8 config3;
-	u64 tmp;
 
-	n = hdmi_compute_n(sample_rate, pixel_clk);
+	drm_hdmi_acr_get_n_cts(ftdms, sample_rate, &n, &cts);
 
 	config3 = hdmi_readb(hdmi, HDMI_CONFIG3_ID);
 
 	/* Compute CTS when using internal AHB audio or General Parallel audio*/
-	if ((config3 & HDMI_CONFIG3_AHBAUDDMA) || (config3 & HDMI_CONFIG3_GPAUD)) {
-		/*
-		 * Compute the CTS value from the N value.  Note that CTS and N
-		 * can be up to 20 bits in total, so we need 64-bit math.  Also
-		 * note that our TDMS clock is not fully accurate; it is
-		 * accurate to kHz.  This can introduce an unnecessary remainder
-		 * in the calculation below, so we don't try to warn about that.
-		 */
-		tmp = (u64)ftdms * n;
-		do_div(tmp, 128 * sample_rate);
-		cts = tmp;
-
-		dev_dbg(hdmi->dev, "%s: fs=%uHz ftdms=%lu.%03luMHz N=%d cts=%d\n",
-			__func__, sample_rate,
-			ftdms / 1000000, (ftdms / 1000) % 1000,
-			n, cts);
-	} else {
+	if (!(config3 & HDMI_CONFIG3_AHBAUDDMA) &&
+	    !(config3 & HDMI_CONFIG3_GPAUD))
 		cts = 0;
-	}
+
+	dev_dbg(hdmi->dev, "%s: fs=%uHz ftdms=%lu.%03luMHz N=%d cts=%d\n",
+		__func__, sample_rate,
+		ftdms / 1000000, (ftdms / 1000) % 1000,
+		n, cts);
 
 	spin_lock_irq(&hdmi->audio_lock);
 	hdmi->audio_n = n;