[alsa-devel] [PATCH v2 0/5] topology: Enhance support for private data

[Takashi Sakamoto]

On Jul 18 2016 11:47, Mengdong Lin wrote:
> Thanks for your suggestions. But this tool is not for directly adding
> controls from the user space.
> 
> It's for ADSP firmware vendors to describe the controls/widgets/pcms for
> a specific version of firmware. Previously, these components are hard
> coded in ASoC platforms drivers and not so convenient to share a common
> driver for different firmwares. The topology binary generated by this
> tool will be loaded by ASoC platform driver with a specific firmware
> binary, and so ASoC will create the controls/widgets/pcms that match the
> firmware automatically.

I know all of what you explained. Therefore, You misunderstand about my
suggestion.

What I suggested is to drop a support of SNDRV_CTL_ELEM_ACCESS_USER flag
from current topology implementation in userspace library, because
current implementation of ALSA SoC part doesn't support it.

In ALSA SoC part, snd_ctl_new1() is called to add a control element set
as a result of parsing binary blob generated by topology implementation.

In snd_ctl_new1(), SNDRV_CTL_ELEM_ACCESS_USER flag is dropped, in these
lines:
http://git.kernel.org/cgit/linux/kernel/git/tiwai/sound.git/tree/sound/core/control.c#n263

Totally, the flag cannot be supported by current implementation of
topology in kernel. Thus, in userspace, we should drop this line to
prevent users from confusions:
http://git.alsa-project.org/?p=alsa-lib.git;a=blob;f=src/topology/ctl.c;h=b948ac021ceecc116bc1087075743243e4b14055;hb=HEAD#l44

That's all what I mentioned. If something unclear, please tell it to me.


Regards

Takashi Sakamoto