ASoC: rockchip: i2s-tdm: Optimize TRCM-resume for QUIRKS_ALWAYS_ON

On the QUIRKS_ALWAYS_ON path, we bring up the clk path on probe
to achieve the clk always on function.

for this situation, the refcount always true, so, we should save
the stream dma state on pause and then do restore on resume.

Signed-off-by: Sugar Zhang <sugar.zhang@rock-chips.com>
Change-Id: I8e45b78a475a468880ef2fb0b358dbdd1169ff08

Author: Sugar Zhang

sound/soc/rockchip/rockchip_i2s_tdm.c

@@ -101,6 +101,7 @@ struct rk_i2s_tdm_dev {
 	bool mclk_calibrate;
 	bool tdm_mode;
 	bool tdm_fsync_half_frame;
+	bool is_dma_active[SNDRV_PCM_STREAM_LAST + 1];
 	unsigned int mclk_rx_freq;
 	unsigned int mclk_tx_freq;
 	unsigned int mclk_root0_freq;
@@ -239,6 +240,18 @@ static inline bool is_stream_active(struct rk_i2s_tdm_dev *i2s_tdm, int stream)
 		return (val & I2S_XFER_RXS_START);
 }
 
+static inline bool is_dma_active(struct rk_i2s_tdm_dev *i2s_tdm, int stream)
+{
+	unsigned int val;
+
+	regmap_read(i2s_tdm->regmap, I2S_DMACR, &val);
+
+	if (stream == SNDRV_PCM_STREAM_PLAYBACK)
+		return (val & I2S_DMACR_TDE_MASK);
+	else
+		return (val & I2S_DMACR_RDE_MASK);
+}
+
 #ifdef HAVE_SYNC_RESET
 #if defined(CONFIG_ARM) && !defined(writeq)
 static inline void __raw_writeq(u64 val, volatile void __iomem *addr)
@@ -623,6 +636,9 @@ static void rockchip_i2s_tdm_trcm_pause(struct snd_pcm_substream *substream,
 	int stream = substream->stream;
 	int bstream = SNDRV_PCM_STREAM_LAST - stream;
 
+	/* store the current state, prepare for resume if necessary */
+	i2s_tdm->is_dma_active[bstream] = is_dma_active(i2s_tdm, bstream);
+
 	/* disable dma for both tx and rx */
 	rockchip_i2s_tdm_dma_ctrl(i2s_tdm, stream, 0);
 	rockchip_i2s_tdm_dma_ctrl(i2s_tdm, bstream, 0);
@@ -638,7 +654,8 @@ static void rockchip_i2s_tdm_trcm_resume(struct snd_pcm_substream *substream,
 	 * just resume bstream, because current stream will be
 	 * startup in the trigger-cmd-START
 	 */
-	rockchip_i2s_tdm_dma_ctrl(i2s_tdm, bstream, 1);
+	if (i2s_tdm->is_dma_active[bstream])
+		rockchip_i2s_tdm_dma_ctrl(i2s_tdm, bstream, 1);
 	rockchip_i2s_tdm_xfer_start(i2s_tdm, bstream);
 }