linux-kernel - Re: [alsa-devel] unload Audio drivers while playback stream is active case kernel crash

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Date:	Thu, 15 Jan 2015 13:40:49 +0900
From:	jiwang <jiada_wang@...tor.com>
To:	Fabio Estevam <festevam@...il.com>,
	Lars-Peter Clausen <lars@...afoo.de>
CC:	Mark Brown <broonie@...nel.org>, Takashi Iwai <tiwai@...e.de>,
	"alsa-devel@...a-project.org" <alsa-devel@...a-project.org>,
	"Frkuska, Joshua" <Joshua_Frkuska@...tor.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"lgirdwood@...il.com" <lgirdwood@...il.com>
Subject: Re: [alsa-devel] unload Audio drivers while playback stream is active
 case kernel crash

Hi
On 01/14/2015 10:43 PM, Fabio Estevam wrote:
> On Wed, Jan 14, 2015 at 10:57 AM, Lars-Peter Clausen <lars@...afoo.de> wrote:
>
>> My personal opinion on this is that disallowing module removal while a
>> driver registered by the module when is in use, while there is no technical
>> reason to do so, is a anti-feature. Whether in ALSA or elsewhere.
>>
>> But looking at the source it seems that this is a core feature of ALSA and
>> at least for the card module itself it will do the ref-counting when a
>> stream is started/stopped. And we even support setting the owner of a card
>> in ASoC. It's just that pretty much no ASoC card driver bothers to set the
>> owner field in the snd_soc_card struct. So this particular problem can be
>> fixed by updating the imx-wm8962 driver to set the owner field.
> Thanks, Lars_Peter. This fixes the issue:
>
> root@...escale /$ modprobe -r snd_soc_imx_wm8962
> modprobe: can't unload module snd_soc_imx_wm8962: Resource temporarily
> unavailable
>
> Will send a patch with your suggestion soon.
I think by set owner field in imx_wm8962 machine driver can fix the 
crash I saw on sabreSD board,
but as this is a generic issue which I suppose should exist on other 
boards with different
machine drivers.

Can we have a more generic fix to this issue?
Or shall we set owner field for all machine drivers?


Thanks,
Jiada
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