ASoC: fsl_sai: Reduce race condition during TE/RE enabling

For trigger start, we don't need to check if it's the first time to
enable TE/RE or second time. It doesn't hurt to enable them any way,
which in the meantime can reduce race condition for TE/RE enabling.

For trigger stop, we will definitely clear FRDE of current direction.
Thus the driver only needs to read the opposite one's.

Signed-off-by: Nicolin Chen <nicoleotsuka@gmail.com>
Signed-off-by: Mark Brown <broonie@linaro.org>

diff --git a/sound/soc/fsl/fsl_sai.c b/sound/soc/fsl/fsl_sai.c
index 1b6ee2ce849fa2469b0b98d4519f71083cde54d7..a437899d2d119ecd2471e62155c21372840d6d3b 100644 (file)
--- a/sound/soc/fsl/fsl_sai.c
+++ b/sound/soc/fsl/fsl_sai.c
@@ -327,7 +327,7 @@ static int fsl_sai_trigger(struct snd_pcm_substream *substream, int cmd,
 {
        struct fsl_sai *sai = snd_soc_dai_get_drvdata(cpu_dai);
        bool tx = substream->stream == SNDRV_PCM_STREAM_PLAYBACK;
-       u32 tcsr, rcsr;
+       u32 xcsr;
 
        /*
         * The transmitter bit clock and frame sync are to be
@@ -338,9 +338,6 @@ static int fsl_sai_trigger(struct snd_pcm_substream *substream, int cmd,
        regmap_update_bits(sai->regmap, FSL_SAI_RCR2, FSL_SAI_CR2_SYNC,
                           FSL_SAI_CR2_SYNC);
 
-       regmap_read(sai->regmap, FSL_SAI_TCSR, &tcsr);
-       regmap_read(sai->regmap, FSL_SAI_RCSR, &rcsr);
-
        /*
         * It is recommended that the transmitter is the last enabled
         * and the first disabled.
@@ -349,12 +346,10 @@ static int fsl_sai_trigger(struct snd_pcm_substream *substream, int cmd,
        case SNDRV_PCM_TRIGGER_START:
        case SNDRV_PCM_TRIGGER_RESUME:
        case SNDRV_PCM_TRIGGER_PAUSE_RELEASE:
-               if (!(tcsr & FSL_SAI_CSR_FRDE || rcsr & FSL_SAI_CSR_FRDE)) {
-                       regmap_update_bits(sai->regmap, FSL_SAI_RCSR,
-                                          FSL_SAI_CSR_TERE, FSL_SAI_CSR_TERE);
-                       regmap_update_bits(sai->regmap, FSL_SAI_TCSR,
-                                          FSL_SAI_CSR_TERE, FSL_SAI_CSR_TERE);
-               }
+               regmap_update_bits(sai->regmap, FSL_SAI_RCSR,
+                                  FSL_SAI_CSR_TERE, FSL_SAI_CSR_TERE);
+               regmap_update_bits(sai->regmap, FSL_SAI_TCSR,
+                                  FSL_SAI_CSR_TERE, FSL_SAI_CSR_TERE);
 
                regmap_update_bits(sai->regmap, FSL_SAI_xCSR(tx),
                                   FSL_SAI_CSR_xIE_MASK, FSL_SAI_FLAGS);
@@ -370,7 +365,8 @@ static int fsl_sai_trigger(struct snd_pcm_substream *substream, int cmd,
                                   FSL_SAI_CSR_xIE_MASK, 0);
 
                /* Check if the opposite FRDE is also disabled */
-               if (!(tx ? rcsr & FSL_SAI_CSR_FRDE : tcsr & FSL_SAI_CSR_FRDE)) {
+               regmap_read(sai->regmap, FSL_SAI_xCSR(!tx), &xcsr);
+               if (!(xcsr & FSL_SAI_CSR_FRDE)) {
                        /* Disable both directions and reset their FIFOs */
                        regmap_update_bits(sai->regmap, FSL_SAI_TCSR,
                                           FSL_SAI_CSR_TERE | FSL_SAI_CSR_FR,