openwrt/target/linux/brcm2708/patches-4.4/0016-bcm2835-i2s-setup-clock-only-if-CPU-is-clock-master.patch

From e2a75ce0e2b6319150e14401f9822adba7895c9c Mon Sep 17 00:00:00 2001
From: Matthias Reichl <hias@horus.com>
Date: Sun, 11 Oct 2015 15:25:51 +0200
Subject: [PATCH 016/232] bcm2835-i2s: setup clock only if CPU is clock master

Code ported from bcm2708-i2s driver in Raspberry Pi tree.

RPi commit c14827ecdaa36607f6110f9ce8df96e698672191 ("bcm2708: Allow
option card devices to be configured via DT")

Original work by Zoltan Szenczi, committed to RPi tree by
Phil Elwell.

Signed-off-by: Matthias Reichl <hias@horus.com>
---
 sound/soc/bcm/bcm2835-i2s.c | 28 +++++++++++++++++++---------
 1 file changed, 19 insertions(+), 9 deletions(-)

--- a/sound/soc/bcm/bcm2835-i2s.c
+++ b/sound/soc/bcm/bcm2835-i2s.c
@@ -411,15 +411,25 @@ static int bcm2835_i2s_hw_params(struct
 		divf = dividend & BCM2835_CLK_DIVF_MASK;
 	}
 
-	/* Set clock divider */
-	regmap_write(dev->clk_regmap, BCM2835_CLK_PCMDIV_REG, BCM2835_CLK_PASSWD
-			| BCM2835_CLK_DIVI(divi)
-			| BCM2835_CLK_DIVF(divf));
+	/* Clock should only be set up here if CPU is clock master */
+	switch (dev->fmt & SND_SOC_DAIFMT_MASTER_MASK) {
+	case SND_SOC_DAIFMT_CBS_CFS:
+	case SND_SOC_DAIFMT_CBS_CFM:
+		/* Set clock divider */
+		regmap_write(dev->clk_regmap, BCM2835_CLK_PCMDIV_REG,
+				  BCM2835_CLK_PASSWD
+				| BCM2835_CLK_DIVI(divi)
+				| BCM2835_CLK_DIVF(divf));
 
-	/* Setup clock, but don't start it yet */
-	regmap_write(dev->clk_regmap, BCM2835_CLK_PCMCTL_REG, BCM2835_CLK_PASSWD
-			| BCM2835_CLK_MASH(mash)
-			| BCM2835_CLK_SRC(clk_src));
+		/* Setup clock, but don't start it yet */
+		regmap_write(dev->clk_regmap, BCM2835_CLK_PCMCTL_REG,
+				  BCM2835_CLK_PASSWD
+				| BCM2835_CLK_MASH(mash)
+				| BCM2835_CLK_SRC(clk_src));
+		break;
+	default:
+		break;
+	}
 
 	/* Setup the frame format */
 	format = BCM2835_I2S_CHEN;