ASoC: sun4i-i2s: Change get_sr() and get_wss() to be more explicit

We are actually using a complex formula to just return a bunch of
simple values. Also this formula is wrong for sun4i when calling
get_wss() the function return 4 instead of 3.

Replace this with a simpler switch case.

Also drop the i2s params which is unused and return a simple int as
returning an error code could be out of range for an s8 and there is
no optim to return a s8 here.

Fixes: 619c15f7 ("ASoC: sun4i-i2s: Change SR and WSS computation")
Reviewed-by: Chen-Yu Tsai <wens@csie.org>
Acked-by: Maxime Ripard <mripard@kernel.org>
Signed-off-by: Clément Péron <peron.clem@gmail.com>
Link: https://lore.kernel.org/r/20201030144648.397824-5-peron.clem@gmail.comSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/sunxi/sun4i-i2s.c

@@ -175,8 +175,8 @@ struct sun4i_i2s_quirks {
 	unsigned int			num_mclk_dividers;
 
 	unsigned long (*get_bclk_parent_rate)(const struct sun4i_i2s *);
-	s8	(*get_sr)(const struct sun4i_i2s *, int);
-	s8	(*get_wss)(const struct sun4i_i2s *, int);
+	int	(*get_sr)(unsigned int width);
+	int	(*get_wss)(unsigned int width);
 
 	/*
 	 * In the set_chan_cfg() function pointer:
@@ -387,37 +387,56 @@ 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)
+static int sun4i_i2s_get_sr(unsigned int width)
 {
-	if (width < 16 || width > 24)
-		return -EINVAL;
+	switch (width) {
+	case 16:
+		return 0;
+	case 20:
+		return 1;
+	case 24:
+		return 2;
+	}
 
-	if (width % 4)
 	return -EINVAL;
-
-	return (width - 16) / 4;
 }
 
-static s8 sun4i_i2s_get_wss(const struct sun4i_i2s *i2s, int width)
+static int sun4i_i2s_get_wss(unsigned int width)
 {
-	if (width < 16 || width > 32)
-		return -EINVAL;
+	switch (width) {
+	case 16:
+		return 0;
+	case 20:
+		return 1;
+	case 24:
+		return 2;
+	case 32:
+		return 3;
+	}
 
-	if (width % 4)
 	return -EINVAL;
-
-	return (width - 16) / 4;
 }
 
-static s8 sun8i_i2s_get_sr_wss(const struct sun4i_i2s *i2s, int width)
+static int sun8i_i2s_get_sr_wss(unsigned int width)
 {
-	if (width % 4)
-		return -EINVAL;
+	switch (width) {
+	case 8:
+		return 1;
+	case 12:
+		return 2;
+	case 16:
+		return 3;
+	case 20:
+		return 4;
+	case 24:
+		return 5;
+	case 28:
+		return 6;
+	case 32:
+		return 7;
+	}
 
-	if (width < 8 || width > 32)
 	return -EINVAL;
-
-	return (width - 8) / 4 + 1;
 }
 
 static int sun4i_i2s_set_chan_cfg(const struct sun4i_i2s *i2s,
@@ -582,11 +601,11 @@ static int sun4i_i2s_hw_params(struct snd_pcm_substream *substream,
 	}
 	i2s->playback_dma_data.addr_width = width;
 
-	sr = i2s->variant->get_sr(i2s, word_size);
+	sr = i2s->variant->get_sr(word_size);
 	if (sr < 0)
 		return -EINVAL;
 
-	wss = i2s->variant->get_wss(i2s, slot_width);
+	wss = i2s->variant->get_wss(slot_width);
 	if (wss < 0)
 		return -EINVAL;