On Mon, 13 Nov 2017 01:14:09 +0100, Takashi Sakamoto wrote:
Hi,
This patchset is to update my previous one: [alsa-devel] [alsa-lib][PATCH 0/2] ctl: deprecate APIs of dimension information http://mailman.alsa-project.org/pipermail/alsa-devel/2017-November/126972.ht...
In ALSA control interface of asound.h, 'struct snd_ctl_elem_info' has 'dimen' member to deliver information for multi-dimensional array, however there's no common way to handle the member. As a result, drivers can force userspace applications to handle the information by inconsistent ways. A series of echoaudio drivers is an actual example of the inconsistent usage.
This issue was addressed in a commit 51db452df07b ('Revert "ALSA: echoaudio: purge contradictions between dimension matrix members and total number of members"') to Linux kernel[1]. Fortunately, at present, this feature of interface is just used by the drivers, and there's a way to obsolete usage of the feature. We can obsolete it without large impacts to userland.
As a result of discussion at Linux miniconference 2017, usage of 'dimen' member of 'struct snd_ctl_elem_info' is going to be deprecated for future removal. This patchset is for proposed tasks at a development period of Linux kernel v4.15[3]. Some APIs of dimension information are deprecated.
In a short discussion in my previous patchset, it's clear that actual removal of kernel interface is uncertain depending on several conditions. Thus the timing to remove the library APIs is not decided yet. This updated version reflects the issue in API documentation (but simply removes statement of the schedule...).
[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/so...
[2] [alsa-devel] [ANNOUNCE] Audio Mini Summit 2017 at Prague, Oct 27 http://mailman.alsa-project.org/pipermail/alsa-devel/2017-July/123110.html
[3] https://github.com/takaswie/presentations/blob/master/20171027/contents.md
Takashi Sakamoto (2): ctl: deprecate APIs of dimensional information test: obsolete usage of APIs of dimensional information
Applied both patches now (with your sign-off).
Thanks!
Takashi