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From 0f409e6c30a04eb85792a6883e81ad2af118c7bd Mon Sep 17 00:00:00 2001
From: Matthias Reichl <github@hias.horus.com>
Date: Thu, 18 Jan 2018 12:36:44 +0100
Subject: [PATCH 161/454] ASoC: bcm2835: fix hw_params error when device is in
prepared state (#2345)
commit 8d5737a5f53902a916ee1e1cb248c9b8b883b2ea upstream.
If bcm2835 is configured as bitclock master calling hw_params()
after prepare() fails with EBUSY. This also makes it impossible to
use bcm2835 in full duplex mode.
The error is caused by the split clock setup: clk_set_rate
is called in hw_params, clk_prepare_enable in prepare. As hw_params
doesn't check if the clock was already enabled clk_set_rate
fails with EBUSY.
Fix this by moving clock startup from prepare to hw_params and
let hw_params properly deal with an already set up or enabled
clock.
Signed-off-by: Matthias Reichl <hias@horus.com>
---
sound/soc/bcm/bcm2835-i2s.c | 20 ++++++++++++++------
1 file changed, 14 insertions(+), 6 deletions(-)
--- a/sound/soc/bcm/bcm2835-i2s.c
+++ b/sound/soc/bcm/bcm2835-i2s.c
@@ -130,6 +130,7 @@ struct bcm2835_i2s_dev {
struct regmap *i2s_regmap;
struct clk *clk;
bool clk_prepared;
+ int clk_rate;
};
static void bcm2835_i2s_start_clock(struct bcm2835_i2s_dev *dev)
@@ -419,10 +420,19 @@ static int bcm2835_i2s_hw_params(struct
}
/* Clock should only be set up here if CPU is clock master */
- if (bit_clock_master) {
- ret = clk_set_rate(dev->clk, bclk_rate);
- if (ret)
- return ret;
+ if (bit_clock_master &&
+ (!dev->clk_prepared || dev->clk_rate != bclk_rate)) {
+ if (dev->clk_prepared)
+ bcm2835_i2s_stop_clock(dev);
+
+ if (dev->clk_rate != bclk_rate) {
+ ret = clk_set_rate(dev->clk, bclk_rate);
+ if (ret)
+ return ret;
+ dev->clk_rate = bclk_rate;
+ }
+
+ bcm2835_i2s_start_clock(dev);
}
/* Setup the frame format */
@@ -618,8 +628,6 @@ static int bcm2835_i2s_prepare(struct sn
struct bcm2835_i2s_dev *dev = snd_soc_dai_get_drvdata(dai);
uint32_t cs_reg;
- bcm2835_i2s_start_clock(dev);
-
/*
* Clear both FIFOs if the one that should be started
* is not empty at the moment. This should only happen
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