Re: [ALSA patch] [PATCH 1/2] alsa: pcm: add unsupported OPS

[Takashi Iwai <tiwai@suse.de>]

On Wed, 10 Jul 2019 16:58:06 +0200,
Miartus, Adam (Arion Recruitment; ADITG/ESM) wrote:
> 
> > -----Original Message-----
> > From: Takashi Iwai <tiwai@suse.de>
> > Sent: Dienstag, 9. Juli 2019 14:25
> > To: Miartus, Adam (Arion Recruitment; ADITG/ESM) <amiartus@de.adit-
> > jv.com>
> > Cc: alsa-devel@alsa-project.org; Pape, Andreas (ADITG/ESS1)
> > <apape@de.adit-jv.com>
> > Subject: Re: [ALSA patch] [PATCH 1/2] alsa: pcm: add unsupported OPS
> > 
> > On Mon, 08 Jul 2019 13:04:48 +0200,
> > Adam Miartus wrote:
> > >
> > > From: Andreas Pape <apape@de.adit-jv.com>
> > >
> > > Signed-off-by: Andreas Pape <apape@de.adit-jv.com>
> > > Signed-off-by: Adam Miartus <amiartus@de.adit-jv.com>
> > 
> > No description isn't good at all.  There must be something you can
> > explain in details here.
> 
> Certainly, I will add explanation in patch v2.
> 
> > 
> > About the changes:
> > 
> > > +#define PCM_UNSUPPORTED_ERR (-ENOSYS)
> > > +void snd_pcm_unsupported_dump(snd_pcm_t *pcm, snd_output_t
> > *out)
> > > +{
> > > +	snd_output_printf(out, "unsupported\n");
> > > +}
> > 
> > IMO, we don't need to show anything if it's dummy.
> > And, maybe it's more straightforward to let the PCM core allow NULL
> > ops?
> > 
> 
> If you agree I could add following in patch v2, then we could drop snd_pcm_unsupported_dump function altogether
> 
> diff --git a/src/pcm/pcm.c b/src/pcm/pcm.c
> index e0ceccc..4d91d4d 100644
> --- a/src/pcm/pcm.c
> +++ b/src/pcm/pcm.c
> @@ -2277,7 +2277,8 @@ int snd_pcm_dump(snd_pcm_t *pcm, snd_output_t *out)
>  {
>         assert(pcm);
>         assert(out);
> -       pcm->ops->dump(pcm->op_arg, out);
> +       if (pcm->ops->dump)
> +               pcm->ops->dump(pcm->op_arg, out);
>         return 0;
>  }

I *guess* this would be simpler in the end, although I'm fine with
your original idea, too.  Let's see and compare the both results.


thanks,

Takashi