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Unverified Commit b880b805 authored by Maciej S. Szmigiero's avatar Maciej S. Szmigiero Committed by Mark Brown
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ASoC: fsl_ssi: serialize AC'97 register access operations 



AC'97 register access operations (both read and write) on SSI use a one,
shared set of SSI registers for AC'97 register address and data.
This means that only one such access is possible at a time and so all these
operations need to be serialized.

Since an AC'97 register access operation in this driver takes 100us+ let's
use a mutex for this.

Use this opportunity to also change a default value returned from AC'97
register read function from -1 to 0, since that's what AC'97 specs require
to be returned when unknown / undefined registers are read.

Signed-off-by: default avatarMaciej S. Szmigiero <mail@maciej.szmigiero.name>
Signed-off-by: default avatarMark Brown <broonie@kernel.org>
parent 695b78b5

sound/soc/fsl/fsl_ssi.c

+22 −4
Original line number Diff line number Diff line
@@ -38,6 +38,7 @@ 
#include <linux/ctype.h>

#include <linux/device.h>

#include <linux/delay.h>

#include <linux/mutex.h>

#include <linux/slab.h>

#include <linux/spinlock.h>

#include <linux/of.h>
@@ -265,6 +266,8 @@ struct fsl_ssi_private { 


	u32 fifo_watermark;

	u32 dma_maxburst;



	struct mutex ac97_reg_lock;

};



/*
@@ -1260,11 +1263,13 @@ static void fsl_ssi_ac97_write(struct snd_ac97 *ac97, unsigned short reg, 
	if (reg > 0x7f)

		return;



	mutex_lock(&fsl_ac97_data->ac97_reg_lock);



	ret = clk_prepare_enable(fsl_ac97_data->clk);

	if (ret) {

		pr_err("ac97 write clk_prepare_enable failed: %d\n",

			ret);

		return;

		goto ret_unlock;

	}



	lreg = reg <<  12;
@@ -1278,6 +1283,9 @@ static void fsl_ssi_ac97_write(struct snd_ac97 *ac97, unsigned short reg, 
	udelay(100);



	clk_disable_unprepare(fsl_ac97_data->clk);



ret_unlock:

	mutex_unlock(&fsl_ac97_data->ac97_reg_lock);

}



static unsigned short fsl_ssi_ac97_read(struct snd_ac97 *ac97,
@@ -1285,16 +1293,18 @@ static unsigned short fsl_ssi_ac97_read(struct snd_ac97 *ac97, 
{

	struct regmap *regs = fsl_ac97_data->regs;



	unsigned short val = -1;

	unsigned short val = 0;

	u32 reg_val;

	unsigned int lreg;

	int ret;



	mutex_lock(&fsl_ac97_data->ac97_reg_lock);



	ret = clk_prepare_enable(fsl_ac97_data->clk);

	if (ret) {

		pr_err("ac97 read clk_prepare_enable failed: %d\n",

			ret);

		return -1;

		goto ret_unlock;

	}



	lreg = (reg & 0x7f) <<  12;
@@ -1309,6 +1319,8 @@ static unsigned short fsl_ssi_ac97_read(struct snd_ac97 *ac97, 


	clk_disable_unprepare(fsl_ac97_data->clk);



ret_unlock:

	mutex_unlock(&fsl_ac97_data->ac97_reg_lock);

	return val;

}
@@ -1569,6 +1581,7 @@ static int fsl_ssi_probe(struct platform_device *pdev) 
	}



	if (fsl_ssi_is_ac97(ssi_private)) {

		mutex_init(&ssi_private->ac97_reg_lock);

		ret = snd_soc_set_ac97_ops_of_reset(&fsl_ssi_ac97_ops, pdev);

		if (ret) {

			dev_err(&pdev->dev, "could not set AC'97 ops\n");
@@ -1663,6 +1676,9 @@ static int fsl_ssi_probe(struct platform_device *pdev) 
		snd_soc_set_ac97_ops(NULL);



error_ac97_ops:

	if (fsl_ssi_is_ac97(ssi_private))

		mutex_destroy(&ssi_private->ac97_reg_lock);



	if (ssi_private->soc->imx)

		fsl_ssi_imx_clean(pdev, ssi_private);
@@ -1681,8 +1697,10 @@ static int fsl_ssi_remove(struct platform_device *pdev) 
	if (ssi_private->soc->imx)

		fsl_ssi_imx_clean(pdev, ssi_private);



	if (fsl_ssi_is_ac97(ssi_private))

	if (fsl_ssi_is_ac97(ssi_private)) {

		snd_soc_set_ac97_ops(NULL);

		mutex_destroy(&ssi_private->ac97_reg_lock);

	}



	return 0;

}