On Tue, 14 Jan 2020 10:48:24 +0100,
jeff_chang(張世佳) wrote:
>
> Dear Takashi:
>
> Thank for your replying.
>
> 1.> +static int mt6660_component_get_volsw(struct snd_kcontrol *kcontrol,
> > + struct snd_ctl_elem_value *ucontrol) {
> > +struct snd_soc_component *component =
> > +snd_soc_kcontrol_component(kcontrol);
> > +struct mt6660_chip *chip = (struct mt6660_chip *)
> > +snd_soc_component_get_drvdata(component);
> > +int ret = -EINVAL;
> > +
> > +if (!strcmp(kcontrol->id.name, "Chip Rev")) {
> > +ucontrol->value.integer.value[0] = chip->chip_rev & 0x0f;
> > +ret = 0;
> > +}
> > +return ret;
>
> So, "T0 SEL" control gets always an error when reading?
> Then can't we pass simply NULL for get ops instead?
>
> Jeff : T0 SEL use snd_soc_get_volsw, it will not use this function.
Then what's the reason of this hackish check?
> 2. So here both 24 and 32 bits data are handled equally, and...
>
> ....
> > +ret = snd_soc_component_update_bits(dai->component,
> > +MT6660_REG_TDM_CFG3, 0x3f0, word_len << 4);
>
> ... word_len is same for both S32 and S24 formats, so there can be no difference between S24 and S32 format handling in the code.
> Meanwhile, the supported formats are:
>
> > +#define STUB_FORMATS(SNDRV_PCM_FMTBIT_S16_LE | \
> > +SNDRV_PCM_FMTBIT_U16_LE | \
> > +SNDRV_PCM_FMTBIT_S24_LE | \
> > +SNDRV_PCM_FMTBIT_U24_LE | \
> > +SNDRV_PCM_FMTBIT_S32_LE | \
> > +SNDRV_PCM_FMTBIT_U32_LE)
>
> Are you sure that S24_* formats really work properly?
>
> Also, the code has no check / setup of the format signedness.
> Do unsigned formats (U16, U24, etc) really work as expected, too?
>
>
> Jeff : Yes, it works.
So, for the codec, it doesn't matter at all about the signedness and
the alingment of 32bit / 24bit of the incoming signals, but magically
handled as is? Interesting...
thanks,
Takashi
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