commit c12c1aad98bb75b435e79c6208b56d2018b42f8b
author Kuninori Morimoto <kuninori.morimoto.gx@renesas.com> Mon Apr 03 06:31:22 2017 +0000
committer Mark Brown <broonie@kernel.org> Wed Apr 05 18:24:07 2017 +0100
tree 62a1d6f3b6ebc7fecab4fb59ebd7d16f0669d0f9
parent a5de5b74a50113564a1e0850e2da96c37c35e55d

ASoC: soc-core: verify Sound Card normality

Current ALSA SoC Sound Card basically consists of CPU/Codec/Platform
components. If system uses Kernel modules, we can disable these drivers
by using rmmod command. In such case, we can't disable
CPU/Codec/Platform driver without disabling Sound Card driver.

But on the other hand, we can disable these drivers by using unbind
command. In such case, we can disable these drivers randomly.
In this case, we can create dirty Sound Card which is missing necessary
components.

(1) If user disabled Sound Card first, but did nothing to other drivers,
user can't use Sound because Sound Card is no longer exists.
(2) If user disabled CPU/Codec/Platform driver randomly, but did nothing
to Sound Card, user still be able to use Sound Card, because dirty Sound
Card still exists. In this case, Sound system will be crashed if user
started sound playback/capture. But we can't block such random unbind
now.

To avoid Sound Card crash in (2) case, we need to unregister Sound Card
whenever CPU/Codec/Platform component were unregistered.
This patch solves this issue.

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Mark Brown <broonie@kernel.org>