Re: [PATCH v5 2/6] ASoC: sgtl5000: Improve VAG power and mute control

[Cezary Rojewski]

On 2019-07-19 09:09, Oleksandr Suvorov wrote:
> On Thu, 18 Jul 2019 at 21:49, Cezary Rojewski <cezary.rojewski@xxxxxxxxx> wrote:
> > On 2019-07-18 20:42, Cezary Rojewski wrote:
> > > On 2019-07-18 11:02, Oleksandr Suvorov wrote:
> > > > +enum {
> > > > +    HP_POWER_EVENT,
> > > > +    DAC_POWER_EVENT,
> > > > +    ADC_POWER_EVENT,
> > > > +    LAST_POWER_EVENT
> > > > +};
> > > > +
> > > > +static u16 mute_mask[] = {
> > > > +    SGTL5000_HP_MUTE,
> > > > +    SGTL5000_OUTPUTS_MUTE,
> > > > +    SGTL5000_OUTPUTS_MUTE
> > > > +};
> > >
> > > If mute_mask[] is only used within common handler, you may consider
> > > declaring const array within said handler instead (did not check that
> > > myself).
> > > Otherwise, simple comment for the second _OUTPUTS_MUTE should suffice -
> > > its not self explanatory why you doubled that mask.
>
> Ok, I'll add a comment to explain doubled mask.
>
> > > > +
> > > >    /* sgtl5000 private structure in codec */
> > > >    struct sgtl5000_priv {
> > > >        int sysclk;    /* sysclk rate */
> > > > @@ -137,8 +157,109 @@ struct sgtl5000_priv {
> > > >        u8 micbias_voltage;
> > > >        u8 lrclk_strength;
> > > >        u8 sclk_strength;
> > > > +    u16 mute_state[LAST_POWER_EVENT];
> > > >    };
> > >
> > > When I spoke of LAST enum constant, I did not really had this specific
> > > usage in mind.
> > >
> > >   From design perspective, _LAST_ does not exist and should never be
> > > referred to as "the next option" i.e.: new enum constant.
>
> By its nature, LAST_POWER_EVENT is actually a size of the array, but I
> couldn't come up with a better name.
>
> > > That is way preferred usage is:
> > > u16 mute_state[ADC_POWER_EVENT+1;
> > > -or-
> > > u16 mute_state[LAST_POWER_EVENT+1];
> > >
> > > Maybe I'm just being radical here :)
>
> Maybe :)  I don't like first variant (ADC_POWER_EVENT+1): somewhen in
> future, someone can add a new event to this enum and we've got a
> possible situation with "out of array indexing".
>
> > > Czarek
> >
> > Forgive me for double posting. Comment above is targeted towards:
> >
> >   >> +enum {
> >   >> +    HP_POWER_EVENT,
> >   >> +    DAC_POWER_EVENT,
> >   >> +    ADC_POWER_EVENT,
> >   >> +    LAST_POWER_EVENT
> >   >> +};
> >
> > as LAST_POWER_EVENT is not assigned explicitly to ADC_POWER_EVENT and
> > thus generates implicit "new option" of value 3.
>
> So will you be happy with the following variant?
> ...
>      ADC_POWER_EVENT,
>      LAST_POWER_EVENT =  ADC_POWER_EVENT,
> ...
>     u16 mute_state[LAST_POWER_EVENT+1];
> ...

It's not about being happy - I'm a happy man in general ;p

As stated already, declaring _LAST_ as the "new option" is misleading 
and not advised.
And yeah, [_LAST_ + 1] is usually the one you should go with.

Czarek