Hi Takashi-san
Thank you for your help
> > > My current headache is ALSA SoC's each modules (= Card/Codec/CPU/Platform)
> > > doesn't care about "unbind/rmmod".
> > > For example, if someone unbinded/rmmoded "Codec", Card or other modules
> > > doesn't know about it. Thus, user can continue to use this sound card,
> > > and kernel will be Oops.
> >
> > Are you sure about this? Have you tried removing a module?
> >
> > During card probe, asoc will hold a reference to the component. See the
> > calls to try_module_get(). This will prevent from unloading under normal
> > cases.
>
> For unloading the module, yes, it should have been prevented by
> managing the module refcount. However, unbinding can't be stopped by
> that. It's a known problem.
>
> Morimoto-san, do you see the issue really via module unloading, or is
> it only via unbinding?
I tried, I thought this issue was for both unload/unbind, but it was only for
unbinding.
is this correct ?
# insmod cpu driver
> insmod home/snd-soc-rcar.ko
[ 94.853449] asoc-simple-graph-dpcm-card
asoc-simple-graph-dpcm-card.0.auto: snd-soc-dummy-dai <-> rsnd-dai.0 mapping ok
[ 94.864466] asoc-simple-graph-dpcm-card
asoc-simple-graph-dpcm-card.0.auto: snd-soc-dummy-dai <-> rsnd-dai.1 mapping ok
[ 94.876047] asoc-simple-graph-dpcm-card
asoc-simple-graph-dpcm-card.0.auto: ak4642-hifi <-> snd-soc-dummy-dai mapping ok
[ 94.888157] rcar_sound ec500000.sound: probed
# check it
> lsmod
Module Size Used by Not tainted
snd_soc_rcar 47695 2
...
# try rmmod
> rmmod snd_soc_rcar
rmmod: can't unload 'snd_soc_rcar': Resource temporarily unavailable
# try playback, it still working
> aplay xxxx.wav
# try unbind
> echo ec500000.sound >
/sys/devices/platform/ec500000.sound/driver/unbind
# sound card will die
> aplay xxxx.wav
[ 230.236466] Unable to handle kernel NULL pointer dereference at
virtual address 00000014
[ 230.244580] pgd = eea60000
[ 230.247320] [00000014] *pgd=6e9a3835, *pte=00000000, *ppte=00000000
[ 230.253628] Internal error: Oops: 17 [#1] SMP ARM
[ 230.258335] Modules linked in: snd_soc_rcar regmap_mmio
...
[ 230.607462] 1fe0: 00000005 bed645b0 b6e2745d b6e28b86 60000030
bed64600 0645484d 82551041
[ 230.615643] Backtrace:
[ 230.618105] [<c02eab58>] (pinctrl_select_state) from [<c02ead14>]
(pinctrl_pm_select_state+0x28/0x58)
[ 230.627330] r9:ee814f00 r8:ee8b8b98 r7:00000000 r6:ee927900
r5:ef2ba410 r4:ee8c9000
[ 230.635131] [<c02eacec>] (pinctrl_pm_select_state) from [<c02ead64>]
(pinctrl_pm_select_default_state+0x20/0x2c)
[ 230.645311] r7:00000000 r6:ee88b200 r5:ef378800 r4:ee8c9000
[ 230.651016] [<c02ead44>] (pinctrl_pm_select_default_state) from
[<c040ab90>] (soc_pcm_open+0x34/0x798)
[ 230.660331] [<c040ab5c>] (soc_pcm_open) from [<c040c0e4>]
(dpcm_fe_dai_open+0xbc/0x524)
[ 230.668340] r10:ee8c9000 r9:ee8b8bb0 r8:ee8b8b98 r7:00000280
r6:ee8c9000 r5:00000001
[ 230.676222] r4:ef378800
...
