At Thu, 1 Jun 2006 15:12:05 +0200 (CEST),
Jaroslav Kysela wrote:
>
> On Thu, 1 Jun 2006, Takashi Iwai wrote:
>
> > At Wed, 31 May 2006 15:10:21 +0200 (CEST),
> > Jaroslav Kysela wrote:
> > >
> > > Hi,
> > >
> > > I've created a minimalistic TLV implemetation for the driver side.
> > > Please, review and comment it. We can add more TLV funcionality in future.
> > > It is essential that user space will handle SNDRV_CTL_TLVT_LEVEL type
> > > immediately (altough it is not used in the kernel space now), otherwise we
> > > cannot group and level TLVs in future.
> >
> > Please never ever include pointers in the ioctl struct.
> > That's to be avoided as much as possible.
>
> > > +struct snd_ctl_tlv {
> > > + unsigned int flags;
> > > + unsigned int length;
> > > + unsigned int value;
> > > + /*
> > > + * TLV structure is:
> > > + * unsigned int length
> > > + * unsigned int type - see SNDRV_CTL_TLVT_*
> > > + * .... data aligned to sizeof(unsigned int), use
> > > + * block_length = (length + (sizeof(unsigned int) - 1)) &
> > > + * ~(sizeof(unsigned int) - 1)) ....
> > > + */
> > > + void *ptr;
> > > +};
>
> So what you suggest? Something like 'struct dm_ioctl'
> (include/linux/dm-ioctl.h) does? Data are stored after ioctl struct.
> It's nearly similar.
Yes. It's similar but a really big difference if you consider about
32/64bit compatibility.
Also, the order of "TLV" is type-length-value.
Takashi
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