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Subject[PATCH V4 2/2] ASoC: fsl_esai: recover the channel swap after xrun
Date
From: Shengjiu Wang <shengjiu.wang@nxp.com>

There is chip errata ERR008000, the reference doc is
(https://www.nxp.com/docs/en/errata/IMX6DQCE.pdf),

The issue is "While using ESAI transmit or receive and
an underrun/overrun happens, channel swap may occur.
The only recovery mechanism is to reset the ESAI."

This issue exist in imx3/imx5/imx6(partial) series.

In this commit add a tasklet to handle reset of ESAI
after xrun happens to recover the channel swap.

Signed-off-by: Shengjiu Wang <shengjiu.wang@nxp.com>
---
sound/soc/fsl/fsl_esai.c | 74 ++++++++++++++++++++++++++++++++++++++++
1 file changed, 74 insertions(+)

diff --git a/sound/soc/fsl/fsl_esai.c b/sound/soc/fsl/fsl_esai.c
index ab460d6d7432..4ce8ac769244 100644
--- a/sound/soc/fsl/fsl_esai.c
+++ b/sound/soc/fsl/fsl_esai.c
@@ -32,6 +32,7 @@
* @extalclk: esai clock source to derive HCK, SCK and FS
* @fsysclk: system clock source to derive HCK, SCK and FS
* @spbaclk: SPBA clock (optional, depending on SoC design)
+ * @task: tasklet to handle the reset operation
* @fifo_depth: depth of tx/rx FIFO
* @slot_width: width of each DAI slot
* @slots: number of slots
@@ -42,6 +43,7 @@
* @sck_div: if using PSR/PM dividers for SCKx clock
* @slave_mode: if fully using DAI slave mode
* @synchronous: if using tx/rx synchronous mode
+ * @reset_at_xrun: flags for enable reset operaton
* @name: driver name
*/
struct fsl_esai {
@@ -53,6 +55,7 @@ struct fsl_esai {
struct clk *extalclk;
struct clk *fsysclk;
struct clk *spbaclk;
+ struct tasklet_struct task;
u32 fifo_depth;
u32 slot_width;
u32 slots;
@@ -65,6 +68,7 @@ struct fsl_esai {
bool sck_div[2];
bool slave_mode;
bool synchronous;
+ bool reset_at_xrun;
char name[32];
};

@@ -73,8 +77,16 @@ static irqreturn_t esai_isr(int irq, void *devid)
struct fsl_esai *esai_priv = (struct fsl_esai *)devid;
struct platform_device *pdev = esai_priv->pdev;
u32 esr;
+ u32 saisr;

regmap_read(esai_priv->regmap, REG_ESAI_ESR, &esr);
+ regmap_read(esai_priv->regmap, REG_ESAI_SAISR, &saisr);
+
+ if ((saisr & (ESAI_SAISR_TUE | ESAI_SAISR_ROE)) &&
+ esai_priv->reset_at_xrun) {
+ dev_dbg(&pdev->dev, "reset module for xrun\n");
+ tasklet_schedule(&esai_priv->task);
+ }

if (esr & ESAI_ESR_TINIT_MASK)
dev_dbg(&pdev->dev, "isr: Transmission Initialized\n");
@@ -635,10 +647,17 @@ static void fsl_esai_trigger_start(struct fsl_esai *esai_priv, bool tx)
ESAI_xSMB_xS_MASK, ESAI_xSMB_xS(mask));
regmap_update_bits(esai_priv->regmap, REG_ESAI_xSMA(tx),
ESAI_xSMA_xS_MASK, ESAI_xSMA_xS(mask));
+
+ /* Enable Exception interrupt */
+ regmap_update_bits(esai_priv->regmap, REG_ESAI_xCR(tx),
+ ESAI_xCR_xEIE_MASK, ESAI_xCR_xEIE);
}

static void fsl_esai_trigger_stop(struct fsl_esai *esai_priv, bool tx)
{
+ regmap_update_bits(esai_priv->regmap, REG_ESAI_xCR(tx),
+ ESAI_xCR_xEIE_MASK, 0);
+
regmap_update_bits(esai_priv->regmap, REG_ESAI_xCR(tx),
tx ? ESAI_xCR_TE_MASK : ESAI_xCR_RE_MASK, 0);
regmap_update_bits(esai_priv->regmap, REG_ESAI_xSMA(tx),
@@ -653,6 +672,51 @@ static void fsl_esai_trigger_stop(struct fsl_esai *esai_priv, bool tx)
ESAI_xFCR_xFR, 0);
}

+static void fsl_esai_hw_reset(unsigned long arg)
+{
+ struct fsl_esai *esai_priv = (struct fsl_esai *)arg;
+ bool tx = true, rx = false, enabled[2];
+ u32 tfcr, rfcr;
+
+ /* Save the registers */
+ regmap_read(esai_priv->regmap, REG_ESAI_TFCR, &tfcr);
+ regmap_read(esai_priv->regmap, REG_ESAI_RFCR, &rfcr);
+ enabled[tx] = tfcr & ESAI_xFCR_xFEN;
+ enabled[rx] = rfcr & ESAI_xFCR_xFEN;
+
+ /* Stop the tx & rx */
+ fsl_esai_trigger_stop(esai_priv, tx);
+ fsl_esai_trigger_stop(esai_priv, rx);
+
+ /* Reset the esai, and ignore return value */
+ fsl_esai_hw_init(esai_priv);
+
+ /* Enforce ESAI personal resets for both TX and RX */
+ regmap_update_bits(esai_priv->regmap, REG_ESAI_TCR,
+ ESAI_xCR_xPR_MASK, ESAI_xCR_xPR);
+ regmap_update_bits(esai_priv->regmap, REG_ESAI_RCR,
+ ESAI_xCR_xPR_MASK, ESAI_xCR_xPR);
+
+ /* Restore registers by regcache_sync, and ignore return value */
+ fsl_esai_register_restore(esai_priv);
+
+ /* Remove ESAI personal resets by configuring PCRC and PRRC also */
+ regmap_update_bits(esai_priv->regmap, REG_ESAI_TCR,
+ ESAI_xCR_xPR_MASK, 0);
+ regmap_update_bits(esai_priv->regmap, REG_ESAI_RCR,
+ ESAI_xCR_xPR_MASK, 0);
+ regmap_update_bits(esai_priv->regmap, REG_ESAI_PRRC,
+ ESAI_PRRC_PDC_MASK, ESAI_PRRC_PDC(ESAI_GPIO));
+ regmap_update_bits(esai_priv->regmap, REG_ESAI_PCRC,
+ ESAI_PCRC_PC_MASK, ESAI_PCRC_PC(ESAI_GPIO));
+
+ /* Restart tx / rx, if they already enabled */
+ if (enabled[tx])
+ fsl_esai_trigger_start(esai_priv, tx);
+ if (enabled[rx])
+ fsl_esai_trigger_start(esai_priv, rx);
+}
+
static int fsl_esai_trigger(struct snd_pcm_substream *substream, int cmd,
struct snd_soc_dai *dai)
{
@@ -857,6 +921,10 @@ static int fsl_esai_probe(struct platform_device *pdev)
esai_priv->pdev = pdev;
snprintf(esai_priv->name, sizeof(esai_priv->name), "%pOFn", np);

+ if (of_device_is_compatible(np, "fsl,vf610-esai") ||
+ of_device_is_compatible(np, "fsl,imx35-esai"))
+ esai_priv->reset_at_xrun = true;
+
/* Get the addresses and IRQ */
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
regs = devm_ioremap_resource(&pdev->dev, res);
@@ -956,6 +1024,9 @@ static int fsl_esai_probe(struct platform_device *pdev)
return ret;
}

+ tasklet_init(&esai_priv->task, fsl_esai_hw_reset,
+ (unsigned long)esai_priv);
+
pm_runtime_enable(&pdev->dev);

regcache_cache_only(esai_priv->regmap, true);
@@ -969,7 +1040,10 @@ static int fsl_esai_probe(struct platform_device *pdev)

static int fsl_esai_remove(struct platform_device *pdev)
{
+ struct fsl_esai *esai_priv = platform_get_drvdata(pdev);
+
pm_runtime_disable(&pdev->dev);
+ tasklet_kill(&esai_priv->task);

return 0;
}
--
2.21.0
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