ASoC: meson: axg-fifo: fix fifo threshold setup

commit 864cee90d4bd870e5d5e5a0b1a6f055f4f951350 upstream.

On TODDR sm1, the fifo threshold register field is slightly different
compared to the other SoCs. This leads to the fifo A being flushed to
memory every 8kB. If the period is smaller than that, several periods
are pushed to memory and notified at once. This is not ideal.

Fix the register field update. With this, the fifos are flushed every
128B. We could still do better, like adapt the threshold depending on
the period size, but at least it consistent across the different
SoC/fifos

Fixes: 5ac825c3d85e ("ASoC: meson: axg-toddr: add sm1 support")
Reported-by: Alden DSouza <aldend@google.com>
Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
Link: https://lore.kernel.org/r/20191218172420.1199117-2-jbrunet@baylibre.com
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

4 files changed, 50 insertions, 28 deletions

diff --git a/sound/soc/meson/axg-fifo.c b/sound/soc/meson/axg-fifo.c
index 5a3749938900..d286dff3171d 100644
--- a/sound/soc/meson/axg-fifo.c
+++ b/sound/soc/meson/axg-fifo.c
@@ -108,10 +108,12 @@ static int axg_fifo_pcm_hw_params(struct snd_pcm_substream *ss,
 {
 	struct snd_pcm_runtime *runtime = ss->runtime;
 	struct axg_fifo *fifo = axg_fifo_data(ss);
+	unsigned int burst_num, period, threshold;
 	dma_addr_t end_ptr;
-	unsigned int burst_num;
 	int ret;
 
+	period = params_period_bytes(params);
+
 	ret = snd_pcm_lib_malloc_pages(ss, params_buffer_bytes(params));
 	if (ret < 0)
 		return ret;
@@ -122,9 +124,25 @@ static int axg_fifo_pcm_hw_params(struct snd_pcm_substream *ss,
 	regmap_write(fifo->map, FIFO_FINISH_ADDR, end_ptr);
 
 	/* Setup interrupt periodicity */
-	burst_num = params_period_bytes(params) / AXG_FIFO_BURST;
+	burst_num = period / AXG_FIFO_BURST;
 	regmap_write(fifo->map, FIFO_INT_ADDR, burst_num);
 
+	/*
+	 * Start the fifo request on the smallest of the following:
+	 * - Half the fifo size
+	 * - Half the period size
+	 */
+	threshold = min(period / 2,
+			(unsigned int)AXG_FIFO_MIN_DEPTH / 2);
+
+	/*
+	 * With the threshold in bytes, register value is:
+	 * V = (threshold / burst) - 1
+	 */
+	threshold /= AXG_FIFO_BURST;
+	regmap_field_write(fifo->field_threshold,
+			   threshold ? threshold - 1 : 0);
+
 	/* Enable block count irq */
 	regmap_update_bits(fifo->map, FIFO_CTRL0,
 			   CTRL0_INT_EN(FIFO_INT_COUNT_REPEAT),
@@ -360,6 +378,11 @@ int axg_fifo_probe(struct platform_device *pdev)
 		return fifo->irq;
 	}
 
+	fifo->field_threshold =
+		devm_regmap_field_alloc(dev, fifo->map, data->field_threshold);
+	if (IS_ERR(fifo->field_threshold))
+		return PTR_ERR(fifo->field_threshold);
+
 	return devm_snd_soc_register_component(dev, data->component_drv,
 					       data->dai_drv, 1);
 }
diff --git a/sound/soc/meson/axg-fifo.h b/sound/soc/meson/axg-fifo.h
index bb1e2ce50256..ab546a3cf940 100644
--- a/sound/soc/meson/axg-fifo.h
+++ b/sound/soc/meson/axg-fifo.h
@@ -9,7 +9,9 @@
 
 struct clk;
 struct platform_device;
+struct reg_field;
 struct regmap;
+struct regmap_field;
 struct reset_control;
 
 struct snd_soc_component_driver;
@@ -50,8 +52,6 @@ struct snd_soc_pcm_runtime;
 #define  CTRL1_STATUS2_SEL_MASK		GENMASK(11, 8)
 #define  CTRL1_STATUS2_SEL(x)		((x) << 8)
 #define   STATUS2_SEL_DDR_READ		0
-#define  CTRL1_THRESHOLD_MASK		GENMASK(23, 16)
-#define  CTRL1_THRESHOLD(x)		((x) << 16)
 #define  CTRL1_FRDDR_DEPTH_MASK		GENMASK(31, 24)
 #define  CTRL1_FRDDR_DEPTH(x)		((x) << 24)
 #define FIFO_START_ADDR			0x08
@@ -67,12 +67,14 @@ struct axg_fifo {
 	struct regmap *map;
 	struct clk *pclk;
 	struct reset_control *arb;
+	struct regmap_field *field_threshold;
 	int irq;
 };
 
 struct axg_fifo_match_data {
 	const struct snd_soc_component_driver *component_drv;
 	struct snd_soc_dai_driver *dai_drv;
+	struct reg_field field_threshold;
 };
 
 extern const struct snd_pcm_ops axg_fifo_pcm_ops;
diff --git a/sound/soc/meson/axg-frddr.c b/sound/soc/meson/axg-frddr.c
index 6ab111c31b28..09773a9ae964 100644
--- a/sound/soc/meson/axg-frddr.c
+++ b/sound/soc/meson/axg-frddr.c
@@ -50,7 +50,7 @@ static int axg_frddr_dai_startup(struct snd_pcm_substream *substream,
 				 struct snd_soc_dai *dai)
 {
 	struct axg_fifo *fifo = snd_soc_dai_get_drvdata(dai);
-	unsigned int fifo_depth, fifo_threshold;
+	unsigned int fifo_depth;
 	int ret;
 
 	/* Enable pclk to access registers and clock the fifo ip */
@@ -68,11 +68,8 @@ static int axg_frddr_dai_startup(struct snd_pcm_substream *substream,
 	 * Depth and threshold are zero based.
 	 */
 	fifo_depth = AXG_FIFO_MIN_CNT - 1;
-	fifo_threshold = (AXG_FIFO_MIN_CNT / 2) - 1;
-	regmap_update_bits(fifo->map, FIFO_CTRL1,
-			   CTRL1_FRDDR_DEPTH_MASK | CTRL1_THRESHOLD_MASK,
-			   CTRL1_FRDDR_DEPTH(fifo_depth) |
-			   CTRL1_THRESHOLD(fifo_threshold));
+	regmap_update_bits(fifo->map, FIFO_CTRL1, CTRL1_FRDDR_DEPTH_MASK,
+			   CTRL1_FRDDR_DEPTH(fifo_depth));
 
 	return 0;
 }
@@ -153,8 +150,9 @@ static const struct snd_soc_component_driver axg_frddr_component_drv = {
 };
 
 static const struct axg_fifo_match_data axg_frddr_match_data = {
-	.component_drv	= &axg_frddr_component_drv,
-	.dai_drv	= &axg_frddr_dai_drv
+	.field_threshold	= REG_FIELD(FIFO_CTRL1, 16, 23),
+	.component_drv		= &axg_frddr_component_drv,
+	.dai_drv		= &axg_frddr_dai_drv
 };
 
 static const struct snd_soc_dai_ops g12a_frddr_ops = {
@@ -271,8 +269,9 @@ static const struct snd_soc_component_driver g12a_frddr_component_drv = {
 };
 
 static const struct axg_fifo_match_data g12a_frddr_match_data = {
-	.component_drv	= &g12a_frddr_component_drv,
-	.dai_drv	= &g12a_frddr_dai_drv
+	.field_threshold	= REG_FIELD(FIFO_CTRL1, 16, 23),
+	.component_drv		= &g12a_frddr_component_drv,
+	.dai_drv		= &g12a_frddr_dai_drv
 };
 
 /* On SM1, the output selection in on CTRL2 */
@@ -335,8 +334,9 @@ static const struct snd_soc_component_driver sm1_frddr_component_drv = {
 };
 
 static const struct axg_fifo_match_data sm1_frddr_match_data = {
-	.component_drv	= &sm1_frddr_component_drv,
-	.dai_drv	= &g12a_frddr_dai_drv
+	.field_threshold	= REG_FIELD(FIFO_CTRL1, 16, 23),
+	.component_drv		= &sm1_frddr_component_drv,
+	.dai_drv		= &g12a_frddr_dai_drv
 };
 
 static const struct of_device_id axg_frddr_of_match[] = {
diff --git a/sound/soc/meson/axg-toddr.c b/sound/soc/meson/axg-toddr.c
index c8ea2145f576..ecf41c7549a6 100644
--- a/sound/soc/meson/axg-toddr.c
+++ b/sound/soc/meson/axg-toddr.c
@@ -89,7 +89,6 @@ static int axg_toddr_dai_startup(struct snd_pcm_substream *substream,
 				 struct snd_soc_dai *dai)
 {
 	struct axg_fifo *fifo = snd_soc_dai_get_drvdata(dai);
-	unsigned int fifo_threshold;
 	int ret;
 
 	/* Enable pclk to access registers and clock the fifo ip */
@@ -107,11 +106,6 @@ static int axg_toddr_dai_startup(struct snd_pcm_substream *substream,
 	/* Apply single buffer mode to the interface */
 	regmap_update_bits(fifo->map, FIFO_CTRL0, CTRL0_TODDR_PP_MODE, 0);
 
-	/* TODDR does not have a configurable fifo depth */
-	fifo_threshold = AXG_FIFO_MIN_CNT - 1;
-	regmap_update_bits(fifo->map, FIFO_CTRL1, CTRL1_THRESHOLD_MASK,
-			   CTRL1_THRESHOLD(fifo_threshold));
-
 	return 0;
 }
 
@@ -185,8 +179,9 @@ static const struct snd_soc_component_driver axg_toddr_component_drv = {
 };
 
 static const struct axg_fifo_match_data axg_toddr_match_data = {
-	.component_drv	= &axg_toddr_component_drv,
-	.dai_drv	= &axg_toddr_dai_drv
+	.field_threshold	= REG_FIELD(FIFO_CTRL1, 16, 23),
+	.component_drv		= &axg_toddr_component_drv,
+	.dai_drv		= &axg_toddr_dai_drv
 };
 
 static const struct snd_soc_dai_ops g12a_toddr_ops = {
@@ -218,8 +213,9 @@ static const struct snd_soc_component_driver g12a_toddr_component_drv = {
 };
 
 static const struct axg_fifo_match_data g12a_toddr_match_data = {
-	.component_drv	= &g12a_toddr_component_drv,
-	.dai_drv	= &g12a_toddr_dai_drv
+	.field_threshold	= REG_FIELD(FIFO_CTRL1, 16, 23),
+	.component_drv		= &g12a_toddr_component_drv,
+	.dai_drv		= &g12a_toddr_dai_drv
 };
 
 static const char * const sm1_toddr_sel_texts[] = {
@@ -282,8 +278,9 @@ static const struct snd_soc_component_driver sm1_toddr_component_drv = {
 };
 
 static const struct axg_fifo_match_data sm1_toddr_match_data = {
-	.component_drv	= &sm1_toddr_component_drv,
-	.dai_drv	= &g12a_toddr_dai_drv
+	.field_threshold	= REG_FIELD(FIFO_CTRL1, 12, 23),
+	.component_drv		= &sm1_toddr_component_drv,
+	.dai_drv		= &g12a_toddr_dai_drv
 };
 
 static const struct of_device_id axg_toddr_of_match[] = {