[PATCH v2] ASoC: sun4i-i2s: Change SR and WSS computation

[PATCH v2] ASoC: sun4i-i2s: Change SR and WSS computation

[Maxime Ripard]

The current computation for the SR (sample resolution) and the WSS (word
slot size) register parameters is based on a switch returning the matching
parameters for a given params width.

Later SoCs (A83t, H3, A64) changed that calculation, which was loosely the
same with an offset. Therefore, an offset was added to adjust those
parameters.

However, the calculation is a bit less trivial than initially thought.
Indeed, while we assumed that SR and WSS were always the same, on older
SoCs, SR will max at 24 (since those SoCs do not support 32 bits formats),
but the word size can be 32.

Newer SoCs can also support a much larger range (8 bits to 32 bits, by
increments of 4) of size than the older SoCs could.

Finally, the A64 and A83t were never adjusted to have that offset in the
first place, and were therefore broken from that point of view.

In order to fix all those issues, let's introduce two functions, get_wss
and get_sr, with their respective implementations for all the SoCs
supported so far.

Fixes: 21faaea1343f ("ASoC: sun4i-i2s: Add support for A83T")
Fixes: 66ecce332538 ("ASoC: sun4i-i2s: Add compatibility with A64 codec I2S")
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>

---

Changes from v1:
  - Declare the structure sun4i_i2s to fix compilation errors
---
 sound/soc/sunxi/sun4i-i2s.c | 71 ++++++++++++++++++++++++++++---------
 1 file changed, 55 insertions(+), 16 deletions(-)

diff --git a/sound/soc/sunxi/sun4i-i2s.c b/sound/soc/sunxi/sun4i-i2s.c
index c53bfed8d4c2..78d44dbc6373 100644
--- a/sound/soc/sunxi/sun4i-i2s.c
+++ b/sound/soc/sunxi/sun4i-i2s.c
@@ -114,6 +114,8 @@
 #define SUN8I_I2S_RX_CHAN_SEL_REG	0x54
 #define SUN8I_I2S_RX_CHAN_MAP_REG	0x58
 
+struct sun4i_i2s;
+
 /**
  * struct sun4i_i2s_quirks - Differences between SoC variants.
  *
@@ -127,7 +129,6 @@
  * @sun4i_i2s_regmap: regmap config to use.
  * @mclk_offset: Value by which mclkdiv needs to be adjusted.
  * @bclk_offset: Value by which bclkdiv needs to be adjusted.
- * @fmt_offset: Value by which wss and sr needs to be adjusted.
  * @field_clkdiv_mclk_en: regmap field to enable mclk output.
  * @field_fmt_wss: regmap field to set word select size.
  * @field_fmt_sr: regmap field to set sample resolution.
@@ -150,7 +151,6 @@ struct sun4i_i2s_quirks {
 	const struct regmap_config	*sun4i_i2s_regmap;
 	unsigned int			mclk_offset;
 	unsigned int			bclk_offset;
-	unsigned int			fmt_offset;
 
 	/* Register fields for i2s */
 	struct reg_field		field_clkdiv_mclk_en;
@@ -163,6 +163,9 @@ struct sun4i_i2s_quirks {
 	struct reg_field		field_rxchanmap;
 	struct reg_field		field_txchansel;
 	struct reg_field		field_rxchansel;
+
+	s8	(*get_sr)(const struct sun4i_i2s *, int);
+	s8	(*get_wss)(const struct sun4i_i2s *, int);
 };
 
 struct sun4i_i2s {
@@ -345,6 +348,39 @@ static int sun4i_i2s_set_clk_rate(struct snd_soc_dai *dai,
 	return 0;
 }
 
+static s8 sun4i_i2s_get_sr(const struct sun4i_i2s *i2s, int width)
+{
+	if (width < 16 || width > 24)
+		return -EINVAL;
+
+	if (width % 4)
+		return -EINVAL;
+
+	return (width - 16) / 4;
+}
+
+static s8 sun4i_i2s_get_wss(const struct sun4i_i2s *i2s, int width)
+{
+	if (width < 16 || width > 32)
+		return -EINVAL;
+
+	if (width % 4)
+		return -EINVAL;
+
+	return (width - 16) / 4;
+}
+
+static s8 sun8i_i2s_get_sr_wss(const struct sun4i_i2s *i2s, int width)
+{
+	if (width % 4)
+		return -EINVAL;
+
+	if (width < 8 || width > 32)
+		return -EINVAL;
+
+	return (width - 8) / 4 + 1;
+}
+
 static int sun4i_i2s_hw_params(struct snd_pcm_substream *substream,
 			       struct snd_pcm_hw_params *params,
 			       struct snd_soc_dai *dai)
@@ -396,22 +432,16 @@ static int sun4i_i2s_hw_params(struct snd_pcm_substream *substream,
 	}
 	i2s->playback_dma_data.addr_width = width;
 
-	switch (params_width(params)) {
-	case 16:
-		sr = 0;
-		wss = 0;
-		break;
+	sr = i2s->variant->get_sr(i2s, params_width(params));
+	if (sr < 0)
+		return -EINVAL;
 
-	default:
-		dev_err(dai->dev, "Unsupported sample width: %d\n",
-			params_width(params));
+	wss = i2s->variant->get_wss(i2s, params_width(params));
+	if (wss < 0)
 		return -EINVAL;
-	}
 
-	regmap_field_write(i2s->field_fmt_wss,
-			   wss + i2s->variant->fmt_offset);
-	regmap_field_write(i2s->field_fmt_sr,
-			   sr + i2s->variant->fmt_offset);
+	regmap_field_write(i2s->field_fmt_wss, wss);
+	regmap_field_write(i2s->field_fmt_sr, sr);
 
 	return sun4i_i2s_set_clk_rate(dai, params_rate(params),
 				      params_width(params));
@@ -887,6 +917,8 @@ static const struct sun4i_i2s_quirks sun4i_a10_i2s_quirks = {
 	.field_rxchanmap	= REG_FIELD(SUN4I_I2S_RX_CHAN_MAP_REG, 0, 31),
 	.field_txchansel	= REG_FIELD(SUN4I_I2S_TX_CHAN_SEL_REG, 0, 2),
 	.field_rxchansel	= REG_FIELD(SUN4I_I2S_RX_CHAN_SEL_REG, 0, 2),
+	.get_sr			= sun4i_i2s_get_sr,
+	.get_wss		= sun4i_i2s_get_wss,
 };
 
 static const struct sun4i_i2s_quirks sun6i_a31_i2s_quirks = {
@@ -904,6 +936,8 @@ static const struct sun4i_i2s_quirks sun6i_a31_i2s_quirks = {
 	.field_rxchanmap	= REG_FIELD(SUN4I_I2S_RX_CHAN_MAP_REG, 0, 31),
 	.field_txchansel	= REG_FIELD(SUN4I_I2S_TX_CHAN_SEL_REG, 0, 2),
 	.field_rxchansel	= REG_FIELD(SUN4I_I2S_RX_CHAN_SEL_REG, 0, 2),
+	.get_sr			= sun4i_i2s_get_sr,
+	.get_wss		= sun4i_i2s_get_wss,
 };
 
 static const struct sun4i_i2s_quirks sun8i_a83t_i2s_quirks = {
@@ -921,6 +955,8 @@ static const struct sun4i_i2s_quirks sun8i_a83t_i2s_quirks = {
 	.field_rxchanmap	= REG_FIELD(SUN4I_I2S_RX_CHAN_MAP_REG, 0, 31),
 	.field_txchansel	= REG_FIELD(SUN4I_I2S_TX_CHAN_SEL_REG, 0, 2),
 	.field_rxchansel	= REG_FIELD(SUN4I_I2S_RX_CHAN_SEL_REG, 0, 2),
+	.get_sr			= sun8i_i2s_get_sr_wss,
+	.get_wss		= sun8i_i2s_get_sr_wss,
 };
 
 static const struct sun4i_i2s_quirks sun8i_h3_i2s_quirks = {
@@ -929,7 +965,6 @@ static const struct sun4i_i2s_quirks sun8i_h3_i2s_quirks = {
 	.sun4i_i2s_regmap	= &sun8i_i2s_regmap_config,
 	.mclk_offset		= 1,
 	.bclk_offset		= 2,
-	.fmt_offset		= 3,
 	.has_fmt_set_lrck_period = true,
 	.has_chcfg		= true,
 	.has_chsel_tx_chen	= true,
@@ -944,6 +979,8 @@ static const struct sun4i_i2s_quirks sun8i_h3_i2s_quirks = {
 	.field_rxchanmap	= REG_FIELD(SUN8I_I2S_RX_CHAN_MAP_REG, 0, 31),
 	.field_txchansel	= REG_FIELD(SUN8I_I2S_TX_CHAN_SEL_REG, 0, 2),
 	.field_rxchansel	= REG_FIELD(SUN8I_I2S_RX_CHAN_SEL_REG, 0, 2),
+	.get_sr			= sun8i_i2s_get_sr_wss,
+	.get_wss		= sun8i_i2s_get_sr_wss,
 };
 
 static const struct sun4i_i2s_quirks sun50i_a64_codec_i2s_quirks = {
@@ -961,6 +998,8 @@ static const struct sun4i_i2s_quirks sun50i_a64_codec_i2s_quirks = {
 	.field_rxchanmap	= REG_FIELD(SUN4I_I2S_RX_CHAN_MAP_REG, 0, 31),
 	.field_txchansel	= REG_FIELD(SUN4I_I2S_TX_CHAN_SEL_REG, 0, 2),
 	.field_rxchansel	= REG_FIELD(SUN4I_I2S_RX_CHAN_SEL_REG, 0, 2),
+	.get_sr			= sun8i_i2s_get_sr_wss,
+	.get_wss		= sun8i_i2s_get_sr_wss,
 };
 
 static int sun4i_i2s_init_regmap_fields(struct device *dev,
-- 
2.21.0


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RE: [alsa-devel] [PATCH v2] ASoC: sun4i-i2s: Change SR and WSS computation

[Rojewski, Cezary]

>From: Alsa-devel [mailto:alsa-devel-bounces@alsa-project.org] On Behalf Of
>Maxime Ripard
>Sent: Wednesday, June 5, 2019 12:08 PM
>To: Mark Brown <broonie@kernel.org>; Liam Girdwood
><lgirdwood@gmail.com>; Mark Rutland <mark.rutland@arm.com>; Rob
>Herring <robh+dt@kernel.org>; Frank Rowand <frowand.list@gmail.com>
>Cc: devicetree@vger.kernel.org; alsa-devel@alsa-project.org; Maxime Ripard
><maxime.ripard@bootlin.com>; Marcus Cooper <codekipper@gmail.com>;
>Chen-Yu Tsai <wens@csie.org>; linux-arm-kernel@lists.infradead.org
>Subject: [alsa-devel] [PATCH v2] ASoC: sun4i-i2s: Change SR and WSS
>computation
>
>The current computation for the SR (sample resolution) and the WSS (word
>slot size) register parameters is based on a switch returning the matching
>parameters for a given params width.
>
>Later SoCs (A83t, H3, A64) changed that calculation, which was loosely the
>same with an offset. Therefore, an offset was added to adjust those
>parameters.
>
>However, the calculation is a bit less trivial than initially thought.
>Indeed, while we assumed that SR and WSS were always the same, on older
>SoCs, SR will max at 24 (since those SoCs do not support 32 bits formats),
>but the word size can be 32.
>
>Newer SoCs can also support a much larger range (8 bits to 32 bits, by
>increments of 4) of size than the older SoCs could.
>
>Finally, the A64 and A83t were never adjusted to have that offset in the
>first place, and were therefore broken from that point of view.
>
>In order to fix all those issues, let's introduce two functions, get_wss
>and get_sr, with their respective implementations for all the SoCs
>supported so far.
>
>Fixes: 21faaea1343f ("ASoC: sun4i-i2s: Add support for A83T")
>Fixes: 66ecce332538 ("ASoC: sun4i-i2s: Add compatibility with A64 codec I2S")
>Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
>
>---
>
>Changes from v1:
>  - Declare the structure sun4i_i2s to fix compilation errors
>---
> sound/soc/sunxi/sun4i-i2s.c | 71 ++++++++++++++++++++++++++++---------
> 1 file changed, 55 insertions(+), 16 deletions(-)
>
>diff --git a/sound/soc/sunxi/sun4i-i2s.c b/sound/soc/sunxi/sun4i-i2s.c
>index c53bfed8d4c2..78d44dbc6373 100644
>--- a/sound/soc/sunxi/sun4i-i2s.c
>+++ b/sound/soc/sunxi/sun4i-i2s.c
>@@ -114,6 +114,8 @@
> #define SUN8I_I2S_RX_CHAN_SEL_REG	0x54
> #define SUN8I_I2S_RX_CHAN_MAP_REG	0x58
>
>+struct sun4i_i2s;
>+
> /**
>  * struct sun4i_i2s_quirks - Differences between SoC variants.
>  *
>@@ -127,7 +129,6 @@
>  * @sun4i_i2s_regmap: regmap config to use.
>  * @mclk_offset: Value by which mclkdiv needs to be adjusted.
>  * @bclk_offset: Value by which bclkdiv needs to be adjusted.
>- * @fmt_offset: Value by which wss and sr needs to be adjusted.
>  * @field_clkdiv_mclk_en: regmap field to enable mclk output.
>  * @field_fmt_wss: regmap field to set word select size.
>  * @field_fmt_sr: regmap field to set sample resolution.
>@@ -150,7 +151,6 @@ struct sun4i_i2s_quirks {
> 	const struct regmap_config	*sun4i_i2s_regmap;
> 	unsigned int			mclk_offset;
> 	unsigned int			bclk_offset;
>-	unsigned int			fmt_offset;
>
> 	/* Register fields for i2s */
> 	struct reg_field		field_clkdiv_mclk_en;
>@@ -163,6 +163,9 @@ struct sun4i_i2s_quirks {
> 	struct reg_field		field_rxchanmap;
> 	struct reg_field		field_txchansel;
> 	struct reg_field		field_rxchansel;
>+
>+	s8	(*get_sr)(const struct sun4i_i2s *, int);
>+	s8	(*get_wss)(const struct sun4i_i2s *, int);
> };
>
> struct sun4i_i2s {
>@@ -345,6 +348,39 @@ static int sun4i_i2s_set_clk_rate(struct snd_soc_dai
>*dai,
> 	return 0;
> }
>
>+static s8 sun4i_i2s_get_sr(const struct sun4i_i2s *i2s, int width)
>+{
>+	if (width < 16 || width > 24)
>+		return -EINVAL;
>+
>+	if (width % 4)
>+		return -EINVAL;
>+
>+	return (width - 16) / 4;
>+}
>+
>+static s8 sun4i_i2s_get_wss(const struct sun4i_i2s *i2s, int width)
>+{
>+	if (width < 16 || width > 32)
>+		return -EINVAL;
>+
>+	if (width % 4)
>+		return -EINVAL;
>+
>+	return (width - 16) / 4;
>+}
>+
>+static s8 sun8i_i2s_get_sr_wss(const struct sun4i_i2s *i2s, int width)
>+{
>+	if (width % 4)
>+		return -EINVAL;
>+

In the two above you start with boundary check before mod yet in this one the order is reversed.
Keeping the same order should prove more cohesive.

>+	if (width < 8 || width > 32)
>+		return -EINVAL;
>+
>+	return (width - 8) / 4 + 1;
>+}
>+

Other, probably less welcome suggestion is introduction of unified function which ones listed here would simply invoke.
All of these "computations" differ in fact only in: min and max boundary. The +1 for _sr_wss is negligible, you can append it on return.

> static int sun4i_i2s_hw_params(struct snd_pcm_substream *substream,
> 			       struct snd_pcm_hw_params *params,
> 			       struct snd_soc_dai *dai)
>@@ -396,22 +432,16 @@ static int sun4i_i2s_hw_params(struct
>snd_pcm_substream *substream,
> 	}
> 	i2s->playback_dma_data.addr_width = width;
>
>-	switch (params_width(params)) {
>-	case 16:
>-		sr = 0;
>-		wss = 0;
>-		break;
>+	sr = i2s->variant->get_sr(i2s, params_width(params));
>+	if (sr < 0)
>+		return -EINVAL;
>
>-	default:
>-		dev_err(dai->dev, "Unsupported sample width: %d\n",
>-			params_width(params));
>+	wss = i2s->variant->get_wss(i2s, params_width(params));
>+	if (wss < 0)
> 		return -EINVAL;
>-	}
>
>-	regmap_field_write(i2s->field_fmt_wss,
>-			   wss + i2s->variant->fmt_offset);
>-	regmap_field_write(i2s->field_fmt_sr,
>-			   sr + i2s->variant->fmt_offset);
>+	regmap_field_write(i2s->field_fmt_wss, wss);
>+	regmap_field_write(i2s->field_fmt_sr, sr);
>
> 	return sun4i_i2s_set_clk_rate(dai, params_rate(params),
> 				      params_width(params));
>@@ -887,6 +917,8 @@ static const struct sun4i_i2s_quirks
>sun4i_a10_i2s_quirks = {
> 	.field_rxchanmap	=
>REG_FIELD(SUN4I_I2S_RX_CHAN_MAP_REG, 0, 31),
> 	.field_txchansel	= REG_FIELD(SUN4I_I2S_TX_CHAN_SEL_REG,
>0, 2),
> 	.field_rxchansel	= REG_FIELD(SUN4I_I2S_RX_CHAN_SEL_REG,
>0, 2),
>+	.get_sr			= sun4i_i2s_get_sr,
>+	.get_wss		= sun4i_i2s_get_wss,
> };
>
> static const struct sun4i_i2s_quirks sun6i_a31_i2s_quirks = {
>@@ -904,6 +936,8 @@ static const struct sun4i_i2s_quirks
>sun6i_a31_i2s_quirks = {
> 	.field_rxchanmap	=
>REG_FIELD(SUN4I_I2S_RX_CHAN_MAP_REG, 0, 31),
> 	.field_txchansel	= REG_FIELD(SUN4I_I2S_TX_CHAN_SEL_REG,
>0, 2),
> 	.field_rxchansel	= REG_FIELD(SUN4I_I2S_RX_CHAN_SEL_REG,
>0, 2),
>+	.get_sr			= sun4i_i2s_get_sr,
>+	.get_wss		= sun4i_i2s_get_wss,
> };
>
> static const struct sun4i_i2s_quirks sun8i_a83t_i2s_quirks = {
>@@ -921,6 +955,8 @@ static const struct sun4i_i2s_quirks
>sun8i_a83t_i2s_quirks = {
> 	.field_rxchanmap	=
>REG_FIELD(SUN4I_I2S_RX_CHAN_MAP_REG, 0, 31),
> 	.field_txchansel	= REG_FIELD(SUN4I_I2S_TX_CHAN_SEL_REG,
>0, 2),
> 	.field_rxchansel	= REG_FIELD(SUN4I_I2S_RX_CHAN_SEL_REG,
>0, 2),
>+	.get_sr			= sun8i_i2s_get_sr_wss,
>+	.get_wss		= sun8i_i2s_get_sr_wss,
> };
>
> static const struct sun4i_i2s_quirks sun8i_h3_i2s_quirks = {
>@@ -929,7 +965,6 @@ static const struct sun4i_i2s_quirks
>sun8i_h3_i2s_quirks = {
> 	.sun4i_i2s_regmap	= &sun8i_i2s_regmap_config,
> 	.mclk_offset		= 1,
> 	.bclk_offset		= 2,
>-	.fmt_offset		= 3,
> 	.has_fmt_set_lrck_period = true,
> 	.has_chcfg		= true,
> 	.has_chsel_tx_chen	= true,
>@@ -944,6 +979,8 @@ static const struct sun4i_i2s_quirks
>sun8i_h3_i2s_quirks = {
> 	.field_rxchanmap	=
>REG_FIELD(SUN8I_I2S_RX_CHAN_MAP_REG, 0, 31),
> 	.field_txchansel	= REG_FIELD(SUN8I_I2S_TX_CHAN_SEL_REG,
>0, 2),
> 	.field_rxchansel	= REG_FIELD(SUN8I_I2S_RX_CHAN_SEL_REG,
>0, 2),
>+	.get_sr			= sun8i_i2s_get_sr_wss,
>+	.get_wss		= sun8i_i2s_get_sr_wss,
> };
>
> static const struct sun4i_i2s_quirks sun50i_a64_codec_i2s_quirks = {
>@@ -961,6 +998,8 @@ static const struct sun4i_i2s_quirks
>sun50i_a64_codec_i2s_quirks = {
> 	.field_rxchanmap	=
>REG_FIELD(SUN4I_I2S_RX_CHAN_MAP_REG, 0, 31),
> 	.field_txchansel	= REG_FIELD(SUN4I_I2S_TX_CHAN_SEL_REG,
>0, 2),
> 	.field_rxchansel	= REG_FIELD(SUN4I_I2S_RX_CHAN_SEL_REG,
>0, 2),
>+	.get_sr			= sun8i_i2s_get_sr_wss,
>+	.get_wss		= sun8i_i2s_get_sr_wss,
> };
>
> static int sun4i_i2s_init_regmap_fields(struct device *dev,
>--
>2.21.0
>
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Re: [alsa-devel] [PATCH v2] ASoC: sun4i-i2s: Change SR and WSS computation

[Maxime Ripard]

[-- Attachment #1.1: Type: text/plain, Size: 1582 bytes --]

Hi,

On Wed, Jun 05, 2019 at 04:36:28PM +0000, Rojewski, Cezary wrote:
> >+static s8 sun4i_i2s_get_sr(const struct sun4i_i2s *i2s, int width)
> >+{
> >+	if (width < 16 || width > 24)
> >+		return -EINVAL;
> >+
> >+	if (width % 4)
> >+		return -EINVAL;
> >+
> >+	return (width - 16) / 4;
> >+}
> >+
> >+static s8 sun4i_i2s_get_wss(const struct sun4i_i2s *i2s, int width)
> >+{
> >+	if (width < 16 || width > 32)
> >+		return -EINVAL;
> >+
> >+	if (width % 4)
> >+		return -EINVAL;
> >+
> >+	return (width - 16) / 4;
> >+}
> >+
> >+static s8 sun8i_i2s_get_sr_wss(const struct sun4i_i2s *i2s, int width)
> >+{
> >+	if (width % 4)
> >+		return -EINVAL;
> >+
>
> In the two above you start with boundary check before mod yet in
> this one the order is reversed.  Keeping the same order should prove
> more cohesive.

Indeed, I'll fix this.

>
> >+	if (width < 8 || width > 32)
> >+		return -EINVAL;
> >+
> >+	return (width - 8) / 4 + 1;
> >+}
> >+
>
> Other, probably less welcome suggestion is introduction of unified
> function which ones listed here would simply invoke. All of these
> "computations" differ in fact only in: min and max boundary. The +1
> for _sr_wss is negligible, you can append it on return.

It's not just about the min and max boundaries. It's also the offset
at which to start with (16 vs 8), and the offset to apply to the
result (0 vs 1).

That's 4 parameters out of 5 that are different. For something that
trivial, I don't think it's worth it to put it in common.

Maxime

--
Maxime Ripard, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

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RE: [alsa-devel] [PATCH v2] ASoC: sun4i-i2s: Change SR and WSS computation

[Rojewski, Cezary]

>Hi,
>
>On Wed, Jun 05, 2019 at 04:36:28PM +0000, Rojewski, Cezary wrote:
>> >+static s8 sun4i_i2s_get_sr(const struct sun4i_i2s *i2s, int width)
>> >+{
>> >+	if (width < 16 || width > 24)
>> >+		return -EINVAL;
>> >+
>> >+	if (width % 4)
>> >+		return -EINVAL;
>> >+
>> >+	return (width - 16) / 4;
>> >+}
>> >+
>> >+static s8 sun4i_i2s_get_wss(const struct sun4i_i2s *i2s, int width)
>> >+{
>> >+	if (width < 16 || width > 32)
>> >+		return -EINVAL;
>> >+
>> >+	if (width % 4)
>> >+		return -EINVAL;
>> >+
>> >+	return (width - 16) / 4;
>> >+}
>> >+
>> >+static s8 sun8i_i2s_get_sr_wss(const struct sun4i_i2s *i2s, int width)
>> >+{
>> >+	if (width % 4)
>> >+		return -EINVAL;
>> >+
>>
>> In the two above you start with boundary check before mod yet in
>> this one the order is reversed.  Keeping the same order should prove
>> more cohesive.
>
>Indeed, I'll fix this.
>
>>
>> >+	if (width < 8 || width > 32)
>> >+		return -EINVAL;
>> >+
>> >+	return (width - 8) / 4 + 1;
>> >+}
>> >+
>>
>> Other, probably less welcome suggestion is introduction of unified
>> function which ones listed here would simply invoke. All of these
>> "computations" differ in fact only in: min and max boundary. The +1
>> for _sr_wss is negligible, you can append it on return.
>
>It's not just about the min and max boundaries. It's also the offset
>at which to start with (16 vs 8), and the offset to apply to the
>result (0 vs 1).
>
>That's 4 parameters out of 5 that are different. For something that
>trivial, I don't think it's worth it to put it in common.
>
>Maxime

This is what was going through my mind:

static inline s8 my_unified(int width, u8 min, u8 max)
{
	if (width < min || width > max)
		return -EINVAL;

	if (width % 4)
		return -EINVAL;

	return (width - min) / 4;
}

static s8 sun4i_i2s_get_sr(const struct sun4i_i2s *i2s, int width)
{
	return my_unified(width, 16, 24);
}

static s8 sun4i_i2s_get_wss(const struct sun4i_i2s *i2s, int width)
{
	return my_unified(width, 16, 32);
}

static s8 sun8i_i2s_get_sr_wss(const struct sun4i_i2s *i2s, int width)
{
	return my_unified(width, 8, 32) + 1;
}

However, if indeed 'start' offset is variable and may differ from min boundary, then my approach would fail.
Otherwise, treat it as suggestion, personally I find it easier to update only the unified function (development phase), especially if you're planning for adding more of these (the min/ max variants) in the future.

One more thing, the i2s ptr is unused - consider flagging it or simply removing from declaration?

Czarek

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Applied "ASoC: sun4i-i2s: Change SR and WSS computation" to the asoc tree

[Mark Brown]

The patch

   ASoC: sun4i-i2s: Change SR and WSS computation

has been applied to the asoc tree at

   https://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound.git for-5.3

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.  

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark

From 619c15f7fac98fbeaae02d76a5529f5026a2b6d7 Mon Sep 17 00:00:00 2001
From: Maxime Ripard <maxime.ripard@bootlin.com>
Date: Wed, 5 Jun 2019 12:08:01 +0200
Subject: [PATCH] ASoC: sun4i-i2s: Change SR and WSS computation

The current computation for the SR (sample resolution) and the WSS (word
slot size) register parameters is based on a switch returning the matching
parameters for a given params width.

Later SoCs (A83t, H3, A64) changed that calculation, which was loosely the
same with an offset. Therefore, an offset was added to adjust those
parameters.

However, the calculation is a bit less trivial than initially thought.
Indeed, while we assumed that SR and WSS were always the same, on older
SoCs, SR will max at 24 (since those SoCs do not support 32 bits formats),
but the word size can be 32.

Newer SoCs can also support a much larger range (8 bits to 32 bits, by
increments of 4) of size than the older SoCs could.

Finally, the A64 and A83t were never adjusted to have that offset in the
first place, and were therefore broken from that point of view.

In order to fix all those issues, let's introduce two functions, get_wss
and get_sr, with their respective implementations for all the SoCs
supported so far.

Fixes: 21faaea1343f ("ASoC: sun4i-i2s: Add support for A83T")
Fixes: 66ecce332538 ("ASoC: sun4i-i2s: Add compatibility with A64 codec I2S")
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
---
 sound/soc/sunxi/sun4i-i2s.c | 71 ++++++++++++++++++++++++++++---------
 1 file changed, 55 insertions(+), 16 deletions(-)

diff --git a/sound/soc/sunxi/sun4i-i2s.c b/sound/soc/sunxi/sun4i-i2s.c
index d5ec1a20499d..03696f880080 100644
--- a/sound/soc/sunxi/sun4i-i2s.c
+++ b/sound/soc/sunxi/sun4i-i2s.c
@@ -118,6 +118,8 @@
 #define SUN8I_I2S_RX_CHAN_SEL_REG	0x54
 #define SUN8I_I2S_RX_CHAN_MAP_REG	0x58
 
+struct sun4i_i2s;
+
 /**
  * struct sun4i_i2s_quirks - Differences between SoC variants.
  *
@@ -131,7 +133,6 @@
  * @sun4i_i2s_regmap: regmap config to use.
  * @mclk_offset: Value by which mclkdiv needs to be adjusted.
  * @bclk_offset: Value by which bclkdiv needs to be adjusted.
- * @fmt_offset: Value by which wss and sr needs to be adjusted.
  * @field_clkdiv_mclk_en: regmap field to enable mclk output.
  * @field_fmt_wss: regmap field to set word select size.
  * @field_fmt_sr: regmap field to set sample resolution.
@@ -154,7 +155,6 @@ struct sun4i_i2s_quirks {
 	const struct regmap_config	*sun4i_i2s_regmap;
 	unsigned int			mclk_offset;
 	unsigned int			bclk_offset;
-	unsigned int			fmt_offset;
 
 	/* Register fields for i2s */
 	struct reg_field		field_clkdiv_mclk_en;
@@ -167,6 +167,9 @@ struct sun4i_i2s_quirks {
 	struct reg_field		field_rxchanmap;
 	struct reg_field		field_txchansel;
 	struct reg_field		field_rxchansel;
+
+	s8	(*get_sr)(const struct sun4i_i2s *, int);
+	s8	(*get_wss)(const struct sun4i_i2s *, int);
 };
 
 struct sun4i_i2s {
@@ -349,6 +352,39 @@ static int sun4i_i2s_set_clk_rate(struct snd_soc_dai *dai,
 	return 0;
 }
 
+static s8 sun4i_i2s_get_sr(const struct sun4i_i2s *i2s, int width)
+{
+	if (width < 16 || width > 24)
+		return -EINVAL;
+
+	if (width % 4)
+		return -EINVAL;
+
+	return (width - 16) / 4;
+}
+
+static s8 sun4i_i2s_get_wss(const struct sun4i_i2s *i2s, int width)
+{
+	if (width < 16 || width > 32)
+		return -EINVAL;
+
+	if (width % 4)
+		return -EINVAL;
+
+	return (width - 16) / 4;
+}
+
+static s8 sun8i_i2s_get_sr_wss(const struct sun4i_i2s *i2s, int width)
+{
+	if (width % 4)
+		return -EINVAL;
+
+	if (width < 8 || width > 32)
+		return -EINVAL;
+
+	return (width - 8) / 4 + 1;
+}
+
 static int sun4i_i2s_hw_params(struct snd_pcm_substream *substream,
 			       struct snd_pcm_hw_params *params,
 			       struct snd_soc_dai *dai)
@@ -400,22 +436,16 @@ static int sun4i_i2s_hw_params(struct snd_pcm_substream *substream,
 	}
 	i2s->playback_dma_data.addr_width = width;
 
-	switch (params_width(params)) {
-	case 16:
-		sr = 0;
-		wss = 0;
-		break;
+	sr = i2s->variant->get_sr(i2s, params_width(params));
+	if (sr < 0)
+		return -EINVAL;
 
-	default:
-		dev_err(dai->dev, "Unsupported sample width: %d\n",
-			params_width(params));
+	wss = i2s->variant->get_wss(i2s, params_width(params));
+	if (wss < 0)
 		return -EINVAL;
-	}
 
-	regmap_field_write(i2s->field_fmt_wss,
-			   wss + i2s->variant->fmt_offset);
-	regmap_field_write(i2s->field_fmt_sr,
-			   sr + i2s->variant->fmt_offset);
+	regmap_field_write(i2s->field_fmt_wss, wss);
+	regmap_field_write(i2s->field_fmt_sr, sr);
 
 	return sun4i_i2s_set_clk_rate(dai, params_rate(params),
 				      params_width(params));
@@ -891,6 +921,8 @@ static const struct sun4i_i2s_quirks sun4i_a10_i2s_quirks = {
 	.field_rxchanmap	= REG_FIELD(SUN4I_I2S_RX_CHAN_MAP_REG, 0, 31),
 	.field_txchansel	= REG_FIELD(SUN4I_I2S_TX_CHAN_SEL_REG, 0, 2),
 	.field_rxchansel	= REG_FIELD(SUN4I_I2S_RX_CHAN_SEL_REG, 0, 2),
+	.get_sr			= sun4i_i2s_get_sr,
+	.get_wss		= sun4i_i2s_get_wss,
 };
 
 static const struct sun4i_i2s_quirks sun6i_a31_i2s_quirks = {
@@ -908,6 +940,8 @@ static const struct sun4i_i2s_quirks sun6i_a31_i2s_quirks = {
 	.field_rxchanmap	= REG_FIELD(SUN4I_I2S_RX_CHAN_MAP_REG, 0, 31),
 	.field_txchansel	= REG_FIELD(SUN4I_I2S_TX_CHAN_SEL_REG, 0, 2),
 	.field_rxchansel	= REG_FIELD(SUN4I_I2S_RX_CHAN_SEL_REG, 0, 2),
+	.get_sr			= sun4i_i2s_get_sr,
+	.get_wss		= sun4i_i2s_get_wss,
 };
 
 static const struct sun4i_i2s_quirks sun8i_a83t_i2s_quirks = {
@@ -925,6 +959,8 @@ static const struct sun4i_i2s_quirks sun8i_a83t_i2s_quirks = {
 	.field_rxchanmap	= REG_FIELD(SUN4I_I2S_RX_CHAN_MAP_REG, 0, 31),
 	.field_txchansel	= REG_FIELD(SUN4I_I2S_TX_CHAN_SEL_REG, 0, 2),
 	.field_rxchansel	= REG_FIELD(SUN4I_I2S_RX_CHAN_SEL_REG, 0, 2),
+	.get_sr			= sun8i_i2s_get_sr_wss,
+	.get_wss		= sun8i_i2s_get_sr_wss,
 };
 
 static const struct sun4i_i2s_quirks sun8i_h3_i2s_quirks = {
@@ -933,7 +969,6 @@ static const struct sun4i_i2s_quirks sun8i_h3_i2s_quirks = {
 	.sun4i_i2s_regmap	= &sun8i_i2s_regmap_config,
 	.mclk_offset		= 1,
 	.bclk_offset		= 2,
-	.fmt_offset		= 3,
 	.has_fmt_set_lrck_period = true,
 	.has_chcfg		= true,
 	.has_chsel_tx_chen	= true,
@@ -948,6 +983,8 @@ static const struct sun4i_i2s_quirks sun8i_h3_i2s_quirks = {
 	.field_rxchanmap	= REG_FIELD(SUN8I_I2S_RX_CHAN_MAP_REG, 0, 31),
 	.field_txchansel	= REG_FIELD(SUN8I_I2S_TX_CHAN_SEL_REG, 0, 2),
 	.field_rxchansel	= REG_FIELD(SUN8I_I2S_RX_CHAN_SEL_REG, 0, 2),
+	.get_sr			= sun8i_i2s_get_sr_wss,
+	.get_wss		= sun8i_i2s_get_sr_wss,
 };
 
 static const struct sun4i_i2s_quirks sun50i_a64_codec_i2s_quirks = {
@@ -965,6 +1002,8 @@ static const struct sun4i_i2s_quirks sun50i_a64_codec_i2s_quirks = {
 	.field_rxchanmap	= REG_FIELD(SUN4I_I2S_RX_CHAN_MAP_REG, 0, 31),
 	.field_txchansel	= REG_FIELD(SUN4I_I2S_TX_CHAN_SEL_REG, 0, 2),
 	.field_rxchansel	= REG_FIELD(SUN4I_I2S_RX_CHAN_SEL_REG, 0, 2),
+	.get_sr			= sun8i_i2s_get_sr_wss,
+	.get_wss		= sun8i_i2s_get_sr_wss,
 };
 
 static int sun4i_i2s_init_regmap_fields(struct device *dev,
-- 
2.20.1


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