Hi Morimoto-san,
On Wed, Mar 29, 2017 at 4:45 AM, Kuninori Morimoto kuninori.morimoto.gx@renesas.com wrote:
Current ALSA SoC Sound Card basically consists of CPU/Codec/Platform drivers. 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 which is missing necessary components 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, what we can do now is, add dirty flag on Sound Card, and avoid to open Sound Card. This patch solved this issue.
Signed-off-by: Kuninori Morimoto kuninori.morimoto.gx@renesas.com
--- a/sound/soc/soc-core.c +++ b/sound/soc/soc-core.c
@@ -3236,6 +3244,8 @@ static void snd_soc_component_cleanup(struct snd_soc_component *component)
static void snd_soc_component_del_unlocked(struct snd_soc_component *component) {
if (component->card)component->card->dirty = 1;
Currently this is the only assignment to .dirty. Can this be undone later, when the driver is bound again?
list_del(&component->list);}
Gr{oetje,eeting}s,
Geert
-- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds