Re: [RFC][PATCH 0/2] ALSA: control: export all of TLV related macros to user land

[Takashi Iwai <tiwai@suse.de>]

On Sat, 10 Sep 2016 06:50:14 +0200,
Takashi Sakamoto wrote:
> 
> Hi,
> 
> Currently, TLV related protocol is not shared to user land. This is not
> good in a point of application interfaces, because application developers
> can't realize the protocol just to see UAPI headers.
> 
> For this purpose, this patchset moves all of macros related to TLV to UAPI
> header. As a result, a header just for kernel land is obsoleted. When adding
> new items to the protocol, it's added to the UAPI header. This change affects
> some drivers in media subsystem.
> 
> In my concern, this change can break applications. When these macros are
> already defined in application side and they includes tlv UAPI header
> directly, 'redefined' warning is generated at preprocess time. But the
> compilation will be success itself. If these two macros have different
> content, the result of preprocess is dominated to the order to define.
> However, the most applications are assumed to use TLV feature via libraries
> such as alsa-lib, thus I'm optimistic to this concern.
> 
> As another my concern, the name of these macros are quite simple, as
> 'TLV_XXX'. It might be help application developers to rename them with a
> prefix, as 'SNDRV_CTL_TLV_XXX'. (But not yet. I'm a lazy guy.)

The second patch does simply wrong.  You must not obsolete
include/sound/tlv.h.  Even if it includes only uapi/*, it should be
still there.

So, just move the stuff to include/uapi/sound/tlv.h, and that's all.


thanks,

Takashi