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: Maciej S. Szmigiero mail@maciej.szmigiero.name --- sound/soc/fsl/fsl_ssi.c | 26 ++++++++++++++++++++++---- 1 file changed, 22 insertions(+), 4 deletions(-)
diff --git a/sound/soc/fsl/fsl_ssi.c b/sound/soc/fsl/fsl_ssi.c index a71bb8391f61..9dea1b16de82 100644 --- a/sound/soc/fsl/fsl_ssi.c +++ b/sound/soc/fsl/fsl_ssi.c @@ -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; };
/* @@ -1262,11 +1265,13 @@ 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; @@ -1280,6 +1285,9 @@ 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, @@ -1287,16 +1295,18 @@ 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; @@ -1311,6 +1321,8 @@ 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; }
@@ -1571,6 +1583,7 @@ 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"); @@ -1665,6 +1678,9 @@ 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);
@@ -1683,8 +1699,10 @@ 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; }