Messages in this thread | | | Date | Wed, 14 Jan 2015 13:57:03 +0100 | From | Lars-Peter Clausen <> | Subject | Re: [alsa-devel] unload Audio drivers while playback stream is active case kernel crash |
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On 01/14/2015 01:02 PM, Mark Brown wrote: [...] >>> I don't think that we need to prevent module unload when a stream is active. >>> From a framework point of view is not different from hot-unplug. I don't >>> see a reason why we'd jump through hoops to actively forbid removing the >>> module once it works just fine. > >> Well, the module unload means a more drastic cleanup. Even if you >> unbind, the code and data are still there while module unload may >> clean them up all. > >> Above all, disallowing the module unload while using is the common >> behavior of any other drivers. Why do we have to be a rebel against >> all civil manner? :) > > That's not true for everything and for ASoC I'd tend to assume that the > user knows what they're doing and has a good reason for it; it's > certainly something that can be helpful in development.
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.
- Lars
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