ASoC: fsl_sai: Improve fsl_sai_isr()

This patch improves fsl_sai_isr() in these ways:
1, Add comment for mask fetching code.
2, Return IRQ_NONE if the IRQ is not for the device.
3, Use regmap_write() instead of regmap_update_bits().

Signed-off-by: Nicolin Chen <Guangyu.Chen@freescale.com>
Signed-off-by: Mark Brown <broonie@linaro.org>
(cherry picked from commit 413312aa17ceefe7003ad690778ab72f023128f0)

diff --git a/sound/soc/fsl/fsl_sai.c b/sound/soc/fsl/fsl_sai.c
index 56da8c8c5960bd0ef99b405560081580a2bd0571..7194d928002087324123017aabc18be2bb852dc9 100644 (file)
--- a/sound/soc/fsl/fsl_sai.c
+++ b/sound/soc/fsl/fsl_sai.c
@@ -30,62 +30,88 @@ static irqreturn_t fsl_sai_isr(int irq, void *devid)
 {
        struct fsl_sai *sai = (struct fsl_sai *)devid;
        struct device *dev = &sai->pdev->dev;
-       u32 xcsr, mask;
+       u32 flags, xcsr, mask;
+       bool irq_none = true;
 
-       /* Only handle those what we enabled */
+       /*
+        * Both IRQ status bits and IRQ mask bits are in the xCSR but
+        * different shifts. And we here create a mask only for those
+        * IRQs that we activated.
+        */
        mask = (FSL_SAI_FLAGS >> FSL_SAI_CSR_xIE_SHIFT) << FSL_SAI_CSR_xF_SHIFT;
 
        /* Tx IRQ */
        regmap_read(sai->regmap, FSL_SAI_TCSR, &xcsr);
-       xcsr &= mask;
+       flags = xcsr & mask;
 
-       if (xcsr & FSL_SAI_CSR_WSF)
+       if (flags)
+               irq_none = false;
+       else
+               goto irq_rx;
+
+       if (flags & FSL_SAI_CSR_WSF)
                dev_dbg(dev, "isr: Start of Tx word detected\n");
 
-       if (xcsr & FSL_SAI_CSR_SEF)
+       if (flags & FSL_SAI_CSR_SEF)
                dev_warn(dev, "isr: Tx Frame sync error detected\n");
 
-       if (xcsr & FSL_SAI_CSR_FEF) {
+       if (flags & FSL_SAI_CSR_FEF) {
                dev_warn(dev, "isr: Transmit underrun detected\n");
                /* FIFO reset for safety */
                xcsr |= FSL_SAI_CSR_FR;
        }
 
-       if (xcsr & FSL_SAI_CSR_FWF)
+       if (flags & FSL_SAI_CSR_FWF)
                dev_dbg(dev, "isr: Enabled transmit FIFO is empty\n");
 
-       if (xcsr & FSL_SAI_CSR_FRF)
+       if (flags & FSL_SAI_CSR_FRF)
                dev_dbg(dev, "isr: Transmit FIFO watermark has been reached\n");
 
-       regmap_update_bits(sai->regmap, FSL_SAI_TCSR,
-                          FSL_SAI_CSR_xF_W_MASK | FSL_SAI_CSR_FR, xcsr);
+       flags &= FSL_SAI_CSR_xF_W_MASK;
+       xcsr &= ~FSL_SAI_CSR_xF_MASK;
+
+       if (flags)
+               regmap_write(sai->regmap, FSL_SAI_TCSR, flags | xcsr);
 
+irq_rx:
        /* Rx IRQ */
        regmap_read(sai->regmap, FSL_SAI_RCSR, &xcsr);
-       xcsr &= mask;
+       flags = xcsr & mask;
 
-       if (xcsr & FSL_SAI_CSR_WSF)
+       if (flags)
+               irq_none = false;
+       else
+               goto out;
+
+       if (flags & FSL_SAI_CSR_WSF)
                dev_dbg(dev, "isr: Start of Rx word detected\n");
 
-       if (xcsr & FSL_SAI_CSR_SEF)
+       if (flags & FSL_SAI_CSR_SEF)
                dev_warn(dev, "isr: Rx Frame sync error detected\n");
 
-       if (xcsr & FSL_SAI_CSR_FEF) {
+       if (flags & FSL_SAI_CSR_FEF) {
                dev_warn(dev, "isr: Receive overflow detected\n");
                /* FIFO reset for safety */
                xcsr |= FSL_SAI_CSR_FR;
        }
 
-       if (xcsr & FSL_SAI_CSR_FWF)
+       if (flags & FSL_SAI_CSR_FWF)
                dev_dbg(dev, "isr: Enabled receive FIFO is full\n");
 
-       if (xcsr & FSL_SAI_CSR_FRF)
+       if (flags & FSL_SAI_CSR_FRF)
                dev_dbg(dev, "isr: Receive FIFO watermark has been reached\n");
 
-       regmap_update_bits(sai->regmap, FSL_SAI_RCSR,
-                          FSL_SAI_CSR_xF_W_MASK | FSL_SAI_CSR_FR, xcsr);
+       flags &= FSL_SAI_CSR_xF_W_MASK;
+       xcsr &= ~FSL_SAI_CSR_xF_MASK;
 
-       return IRQ_HANDLED;
+       if (flags)
+               regmap_write(sai->regmap, FSL_SAI_TCSR, flags | xcsr);
+
+out:
+       if (irq_none)
+               return IRQ_NONE;
+       else
+               return IRQ_HANDLED;
 }
 
 static int fsl_sai_set_dai_sysclk_tr(struct snd_soc_dai *cpu_dai,