On 10/13/2015 04:18 PM, Koro Chen wrote: > On Tue, 2015-10-13 at 15:44 +0200, Lars-Peter Clausen wrote: >> On 10/13/2015 03:37 PM, Koro Chen wrote: >>> The patch "ASoC: Prevent components from being bound to multiple cards" >>> adds check to prevent multiple cards from using the same component. >>> However, snd_soc_register_platform() or snd_soc_register_codec() will >>> also create components, and sharing the same platform by multiple cards >>> is then refused. This happens with a platform having multiple >>> independent DAIs that share the same DMA controller. >>> >>> Relax the condition by checking component->registered_as_component, >>> which is only true in case of snd_soc_register_component() and >>> will be false for components created by snd_soc_register_platform() >>> or snd_soc_register_codec(). >> >> Binding a component to multiple cards results in internal data structure >> corruption, regardless of whether it is a raw component, CODEC or platform, >> which is why the check was added. So the proposed change wont work. >> > Thanks for your comment. Is it possible to share an example of how the > data structure will be corrupted? So I can study into this further.
Just look at soc_probe_component() and think about what happens if that runs twice for two different cards. Multiple calls to list_add() on the same list, controls are added multiple times, DAPM widgets are created multiple times, the card field will only point to the last card. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
