950-0187-rpi-wm8804-soundcard-configure-wm8804-clocks-only-on.patch

From f6b133a056e8fde7f4707e2874e204c7d5d671a2 Mon Sep 17 00:00:00 2001
From: Matthias Reichl <hias@horus.com>
Date: Sun, 18 Nov 2018 15:32:28 +0100
Subject: [PATCH] rpi-wm8804-soundcard: configure wm8804 clocks only on
 rate change

This should avoid clicks when stopping and immediately afterwards
starting a stream with the same samplerate as before.

Signed-off-by: Matthias Reichl <hias@horus.com>
---
 sound/soc/bcm/rpi-wm8804-soundcard.c | 9 +++++++++
 1 file changed, 9 insertions(+)

--- a/sound/soc/bcm/rpi-wm8804-soundcard.c
+++ b/sound/soc/bcm/rpi-wm8804-soundcard.c
@@ -64,6 +64,7 @@ struct snd_rpi_wm8804_drvdata {
 
 static struct gpio_desc *snd_clk44gpio;
 static struct gpio_desc *snd_clk48gpio;
+static int wm8804_samplerate = 0;
 
 #define CLK_44EN_RATE 22579200UL
 #define CLK_48EN_RATE 24576000UL
@@ -117,6 +118,12 @@ static int snd_rpi_wm8804_hw_params(stru
 	struct wm8804_clk_cfg clk_cfg;
 	int samplerate = params_rate(params);
 
+	if (samplerate == wm8804_samplerate)
+		return 0;
+
+	/* clear until all clocks are setup properly */
+	wm8804_samplerate = 0;
+
 	snd_rpi_wm8804_clk_cfg(samplerate, &clk_cfg);
 
 	pr_debug("%s samplerate: %d mclk_freq: %u mclk_div: %u sysclk: %u\n",
@@ -163,6 +170,8 @@ static int snd_rpi_wm8804_hw_params(stru
 		return ret;
 	}
 
+	wm8804_samplerate = samplerate;
+
 	/* set sampling frequency status bits */
 	snd_soc_component_update_bits(component, WM8804_SPDTX4, 0x0f,
 			sampling_freq);