[alsa-devel] [PATCH 4/4] ASoC: soc-core: call snd_soc_remove_card() when component del

[Kuninori Morimoto]

Hi Lars

> >> ASoC devices are organized as CPU-CARD-CODEC. Then, CPU/CODEC
> >> are based on component structure. Now, each CARD device knows
> >> connected component. But CARD doesn't notice if connected component
> >> was removed when user called rmmod or unbind in current implementation.
> >> Thus, CARD which lost some components still exist in system.
> >> And then, ALSA sound card will have some problem if user used this CARD
> >> in such timing. This patch temporarily removes CARD from system
> >> if connected component was removed, and re-add it if some component
> >> was added.
> >>
> >> Reported-by: Nguyen Viet Dung <nv-dung at jinso.co.jp>
> >> Reported-by: Bui Duc Phuc <bd-phuc at jinso.co.jp>
> >> Reported-by: Cao Minh Hiep <cm-hiep at jinso.co.jp>
> >> Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx at renesas.com>
> >> ---
(snip)
> The other issue is that it introduces subtly issues with the suspend and 
> resume order. Suspend and resume are called in the order in which the probe 
> functions of devices are called (and succeed). By returning -EPROBE_DEFER in 
> the card driver we make sure that the card's probe function is always called 
> after the probe functions of all the components of the card have run. This 
> again causes the card's suspend function to be called before any suspend 
> function of any of it's components. Now with this patch it is possible again 
> for a component's probe function to be called after the card's probe 
> function which changes the suspend and resume order and might break things.
> 
> This patch essentially is a partial revert of commit b19e6e7b763 ("ASoC: 
> core: Use driver core probe deferral") where the card list was replaced with 
> the -EPROBE_DEFER mechanism.
> 
> So while this patch fixes the nasty crash it introduces some other subtle 
> issue. Maybe we should also add a big WARN() when a component of a card is 
> removed while still in use until the other issues are also fixed.

OK. I can send such patch.
Oops ? does this mean my patch-set + WARN() ? or just WARN() ?


Best regards
---
Kuninori Morimoto