Hi,
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.
[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/sound/pci/echoaudio?id=51db452df07bb4c5754b73789253ba21681d9dc2
[2] [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 dimension information
test: obsolete usage of APIs of dimension information
src/control/control.c | 12 ++++++++++++
test/user-ctl-element-set.c | 31 -------------------------------
2 files changed, 12 insertions(+), 31 deletions(-)
--
2.11.0
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