[PATCH v4] sound: rawmidi: Add framing mode

[Takashi Iwai]

On Sun, 11 Apr 2021 19:52:21 +0200,
Jaroslav Kysela wrote:
> >>>   struct snd_rawmidi_params {
> >>>   	int stream;
> >>>   	size_t buffer_size;		/* queue size in bytes */
> >>>   	size_t avail_min;		/* minimum avail bytes for wakeup */
> >>>   	unsigned int no_active_sensing: 1; /* do not send active sensing byte in close() */
> >>> -	unsigned char reserved[16];	/* reserved for future use */
> >>> +	unsigned char framing;		/* For input data only, frame incoming data */
> >> We can move this flag to above 32-bit word (no_active_sensing). I'm not sure,
> >> if we need 8 bits for this. It's first change after 20 years. Another flag may
> >> obsolete this one.
> > 
> > Not sure what you mean by this, could you show the code? Framing is an 
> > enum rather than a flag, in case we find other framing formats with 
> > other sizes that would obsolete this one.
> 
> unsigned int no_active_sensing: 1;
> unsigned int framing32: 1;
> unsigned int framing64: 1; /* future extension, framing32 == 0 in this case */
> 
> or:
> 
> unsigned int framing_mode: 3;	/* three bits for future types */
> 
> perhaps also:
> 
> unsigned int clock_type: 3;	/* three bits for the clock type selection */

The usage of bit fields in an ioctl struct is a bad idea from the
compat layer POV.  Let's avoid it.


thanks,

Takashi