ASoC: meson: axg-fifo: add NO_PERIOD_WAKEUP support

On the AXG family, the fifo irq is not necessary for the HW to operate.
It is just used to notify that a period has elapsed. If userpace does not
care for these wakeups (such as pipewire), we are just wasting CPU cycles.

Add support for NO_PERIOD_WAKEUP and disable irq when they are no needed.
Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
Link: https://lore.kernel.org/r/20210407145914.311479-1-jbrunet@baylibre.comSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/meson/axg-fifo.c

@@ -27,8 +27,8 @@ static struct snd_pcm_hardware axg_fifo_hw = {
 		 SNDRV_PCM_INFO_MMAP |
 		 SNDRV_PCM_INFO_MMAP_VALID |
 		 SNDRV_PCM_INFO_BLOCK_TRANSFER |
-		 SNDRV_PCM_INFO_PAUSE),
-
+		 SNDRV_PCM_INFO_PAUSE |
+		 SNDRV_PCM_INFO_NO_PERIOD_WAKEUP),
 	.formats = AXG_FIFO_FORMATS,
 	.rate_min = 5512,
 	.rate_max = 192000,
@@ -113,7 +113,7 @@ int axg_fifo_pcm_hw_params(struct snd_soc_component *component,
 {
 	struct snd_pcm_runtime *runtime = ss->runtime;
 	struct axg_fifo *fifo = axg_fifo_data(ss);
-	unsigned int burst_num, period, threshold;
+	unsigned int burst_num, period, threshold, irq_en;
 	dma_addr_t end_ptr;
 
 	period = params_period_bytes(params);
@@ -142,10 +142,11 @@ int axg_fifo_pcm_hw_params(struct snd_soc_component *component,
 	regmap_field_write(fifo->field_threshold,
 			   threshold ? threshold - 1 : 0);
 
-	/* Enable block count irq */
+	/* Enable irq if necessary  */
+	irq_en = runtime->no_period_wakeup ? 0 : FIFO_INT_COUNT_REPEAT;
 	regmap_update_bits(fifo->map, FIFO_CTRL0,
 			   CTRL0_INT_EN(FIFO_INT_COUNT_REPEAT),
-			   CTRL0_INT_EN(FIFO_INT_COUNT_REPEAT));
+			   CTRL0_INT_EN(irq_en));
 
 	return 0;
 }