[alsa-devel] [PATCH - alsa-lib 1/1] Change card/pid get functions to return -ENOSYS if the kernel is too old

[Adam Goode]

On Fri, Apr 8, 2016 at 1:56 PM, Martin Koegler <martin.koegler at chello.at>
wrote:

> On Fri, Apr 08, 2016 at 11:21:57AM -0400, Adam Goode wrote:
> > So there are 2 alternatives I can think of:
> >
> > option 1: introduce snd_seq_client_info_get_pid_2() and leave the
> existing
> > function alone. This new function can return a new constant,
> > SND_SEQ_CLIENT_INFO_PID_UNKNOWN for missing kernel support. Same for
> card.
> > option 2: introduce snd_seq_client_info_pid_known() that returns a bool
> if
> > there is kernel support. Same for card.
>
> I wouldn't implement option 1. Using that methode for API changes will
> result in lots of rarely used functions.
>
> Chrome will probable need that information to enable a fallback-code - if
> a application has no fallback code,
> it has no need for different returncodes. In a few years, most
> distributions will likely ship kernel including that functions,
> so there is no need to for fallback-code and the kernel support check any
> more.
>
> Why not a snd_seq_client_info_get_capatibilites() returing bit flags:
> .._CAP_CARD_NUMBER | .._CAP_PID ?
>
>
This approach is fine by me as well, though it does introduce more
constants and bitwise logic.


Adam




> Regards,
> Martin
>