[alsa-devel] Why use spin_lock or spin_lock_irq in trigger callback (audio capture)?

[Clemens Ladisch]

Yiliang Bao wrote:
> I looked at some PCI audio capture driver like BT878 (sound/pci/bt87x.c) or
> SAA7134 (drivers/media/video/saa7134-alsa.c), I found that spin_lock instead
> of spin_lock_irq (or spin_lock_irqsave) is used in trigger function. Is
> there any reason for that?

Yes, the trigger callback is called with interrupts already disabled.
http://www.alsa-project.org/~tiwai/writing-an-alsa-driver/ch05s08.html


Regards,
Clemens