linux-kernel - [PATCH v3 3/4] ASoC: pcm512x: Move format check into `set

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Date:   Sun, 15 Nov 2020 13:23:05 +0100
From:   Kirill Marinushkin <kmarinushkin@...dec.com>
To:     Mark Brown <broonie@...nel.org>, Takashi Iwai <tiwai@...e.com>,
        Liam Girdwood <lgirdwood@...il.com>,
        Peter Ujfalusi <peter.ujfalusi@...com>
Cc:     Matthias Reichl <hias@...us.com>,
        Kuninori Morimoto <kuninori.morimoto.gx@...esas.com>,
        alsa-devel@...a-project.org, linux-kernel@...r.kernel.org,
        Kirill Marinushkin <kmarinushkin@...dec.com>
Subject: [PATCH v3 3/4] ASoC: pcm512x: Move format check into `set_fmt()`

I would like to describe the reasoning by quoting Peter Ujfalusi
<peter.ujfalusi@...com> from his review of this patch series v1 [1]:

> When you bind a link you will use set_fmt for the two sides to see if
> they can agree, that both can support what has been asked.
>
> The pcm512x driver just saves the fmt and say back to that card:
> whatever, I'm fine with it. But runtime during hw_params it can fail due
> to unsupported bus format, which it actually acked to be ok.
>
> This is the difference.
>
> Sure, some device have constraint based on the fmt towards the hw_params
> and it is perfectly OK to do such a checks and rejections or build
> rules/constraints based on fmt, but failing hw_params just because
> set_fmt did not checked that the bus format is not even supported is not
> a nice thing to do.

[1] https://patchwork.kernel.org/project/alsa-devel/patch/
    20201109212133.25869-1-kmarinushkin@...dec.com/

Signed-off-by: Kirill Marinushkin <kmarinushkin@...dec.com>
Cc: Mark Brown <broonie@...nel.org>
Cc: Takashi Iwai <tiwai@...e.com>
Cc: Liam Girdwood <lgirdwood@...il.com>
Cc: Matthias Reichl <hias@...us.com>
Cc: Kuninori Morimoto <kuninori.morimoto.gx@...esas.com>
Cc: Peter Ujfalusi <peter.ujfalusi@...com>
Cc: alsa-devel@...a-project.org
Cc: linux-kernel@...r.kernel.org
---
 sound/soc/codecs/pcm512x.c | 55 +++++++++++++++++++++++++---------------------
 1 file changed, 30 insertions(+), 25 deletions(-)

diff --git a/sound/soc/codecs/pcm512x.c b/sound/soc/codecs/pcm512x.c
index aa55a477a28f..22ef77955a28 100644
--- a/sound/soc/codecs/pcm512x.c
+++ b/sound/soc/codecs/pcm512x.c
@@ -1168,8 +1168,6 @@ static int pcm512x_hw_params(struct snd_pcm_substream *substream,
 	struct pcm512x_priv *pcm512x = snd_soc_component_get_drvdata(component);
 	int alen;
 	int gpio;
-	int clock_output;
-	int master_mode;
 	int ret;
 
 	dev_dbg(component->dev, "hw_params %u Hz, %u channels\n",
@@ -1202,11 +1200,8 @@ static int pcm512x_hw_params(struct snd_pcm_substream *substream,
 		return ret;
 	}
 
-	switch (pcm512x->fmt & SND_SOC_DAIFMT_MASTER_MASK) {
-	case SND_SOC_DAIFMT_CBS_CFS:
-		clock_output = 0;
-		master_mode = 0;
-
+	if ((pcm512x->fmt & SND_SOC_DAIFMT_MASTER_MASK) ==
+	    SND_SOC_DAIFMT_CBS_CFS) {
 		ret = regmap_update_bits(pcm512x->regmap, PCM512x_ERROR_DETECT,
 					 PCM512x_DCAS, 0);
 		if (ret != 0) {
@@ -1216,16 +1211,6 @@ static int pcm512x_hw_params(struct snd_pcm_substream *substream,
 			return ret;
 		}
 		goto skip_pll;
-	case SND_SOC_DAIFMT_CBM_CFM:
-		clock_output = PCM512x_BCKO | PCM512x_LRKO;
-		master_mode = PCM512x_RLRK | PCM512x_RBCK;
-		break;
-	case SND_SOC_DAIFMT_CBM_CFS:
-		clock_output = PCM512x_BCKO;
-		master_mode = PCM512x_RBCK;
-		break;
-	default:
-		return -EINVAL;
 	}
 
 	if (pcm512x->pll_out) {
@@ -1343,6 +1328,34 @@ static int pcm512x_hw_params(struct snd_pcm_substream *substream,
 	}
 
 skip_pll:
+	return 0;
+}
+
+static int pcm512x_set_fmt(struct snd_soc_dai *dai, unsigned int fmt)
+{
+	struct snd_soc_component *component = dai->component;
+	struct pcm512x_priv *pcm512x = snd_soc_component_get_drvdata(component);
+	int clock_output;
+	int master_mode;
+	int ret;
+
+	switch (fmt & SND_SOC_DAIFMT_MASTER_MASK) {
+	case SND_SOC_DAIFMT_CBS_CFS:
+		clock_output = 0;
+		master_mode = 0;
+		break;
+	case SND_SOC_DAIFMT_CBM_CFM:
+		clock_output = PCM512x_BCKO | PCM512x_LRKO;
+		master_mode = PCM512x_RLRK | PCM512x_RBCK;
+		break;
+	case SND_SOC_DAIFMT_CBM_CFS:
+		clock_output = PCM512x_BCKO;
+		master_mode = PCM512x_RBCK;
+		break;
+	default:
+		return -EINVAL;
+	}
+
 	ret = regmap_update_bits(pcm512x->regmap, PCM512x_BCLK_LRCLK_CFG,
 				 PCM512x_BCKP | PCM512x_BCKO | PCM512x_LRKO,
 				 clock_output);
@@ -1359,14 +1372,6 @@ static int pcm512x_hw_params(struct snd_pcm_substream *substream,
 		return ret;
 	}
 
-	return 0;
-}
-
-static int pcm512x_set_fmt(struct snd_soc_dai *dai, unsigned int fmt)
-{
-	struct snd_soc_component *component = dai->component;
-	struct pcm512x_priv *pcm512x = snd_soc_component_get_drvdata(component);
-
 	pcm512x->fmt = fmt;
 
 	return 0;
-- 
2.13.6