Re: [greybus-dev] [PATCH 3/3] [PATCH] staging: greybus: __u8 is sufficient for snd_ctl_elem_type_t and snd_ctl_elem_iface_t

[Coiby Xu]

On Fri, Sep 25, 2020 at 11:02:23AM -0500, Alex Elder wrote:
> On 9/25/20 9:11 AM, Coiby Xu wrote:
> > On Thu, Sep 24, 2020 at 10:54:50AM +0000, David Laight wrote:
> > > From: Coiby Xu
> > > > Sent: 24 September 2020 11:21
> > > > Use __8 to replace int and remove the unnecessary __bitwise type
> > > > attribute.
> > > >
> > > > Found by sparse,
> > > ...
> > > > diff --git a/include/uapi/sound/asound.h b/include/uapi/sound/asound.h
> > > > index 535a7229e1d9..8e71a95644ab 100644
> > > > --- a/include/uapi/sound/asound.h
> > > > +++ b/include/uapi/sound/asound.h
> > > > @@ -950,7 +950,7 @@ struct snd_ctl_card_info {
> > > >      unsigned char components[128];    /* card components / fine
> > > > identification, delimited with one
> > > > space (AC97 etc..) */
> > > >  };
> > > >
> > > > -typedef int __bitwise snd_ctl_elem_type_t;
> > > > +typedef __u8 snd_ctl_elem_type_t;
> > > >  #define    SNDRV_CTL_ELEM_TYPE_NONE    ((__force
> > > > snd_ctl_elem_type_t) 0) /* invalid */
> > > >  #define    SNDRV_CTL_ELEM_TYPE_BOOLEAN    ((__force
> > > > snd_ctl_elem_type_t) 1) /* boolean type */
> > > >  #define    SNDRV_CTL_ELEM_TYPE_INTEGER    ((__force
> > > > snd_ctl_elem_type_t) 2) /* integer type */
> > >
> > > WTF is all that about anyway??
> > > What is wrong with:
> > > #define    SNDRV_CTL_ELEM_TYPE_NONE    0u /* invalid */
> >
> > I'm sorry I don't quite understand you. Are you suggesting
> > SNDRV_CTL_ELEM_TYPE_NONE
> > isn't needed in the first place?
>
> I think David is asking why it's defined the way it is,
> and I'd guess it's to have the compiler issue an error
> if you attempt to assign one of these values to a variable
> or field of the wrong type.
>
> No, you should not attempt to change this.

Thank you for the explanation!

> 					-Alex
> > >     David
> > >
> > > -
> > > Registered Address Lakeside, Bramley Road, Mount Farm, Milton
> > > Keynes, MK1 1PT, UK
> > > Registration No: 1397386 (Wales)
> >
> > --
> > Best regards,
> > Coiby
> > _______________________________________________
> > greybus-dev mailing list
> > greybus-dev@xxxxxxxxxxxxxxxx
> > https://lists.linaro.org/mailman/listinfo/greybus-dev

--
Best regards,
Coiby