I would like to describe the reasoning by quoting Peter Ujfalusi <peter.ujfalusi@xxxxxx> 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@xxxxxxxxxx/ Signed-off-by: Kirill Marinushkin <kmarinushkin@xxxxxxxxxx> Cc: Mark Brown <broonie@xxxxxxxxxx> Cc: Takashi Iwai <tiwai@xxxxxxxx> Cc: Liam Girdwood <lgirdwood@xxxxxxxxx> Cc: Matthias Reichl <hias@xxxxxxxxx> Cc: Kuninori Morimoto <kuninori.morimoto.gx@xxxxxxxxxxx> Cc: Peter Ujfalusi <peter.ujfalusi@xxxxxx> Cc: alsa-devel@xxxxxxxxxxxxxxxx Cc: linux-kernel@xxxxxxxxxxxxxxx --- 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
