Question:add Iirq mask method in irq disable call.
Thomas Gleixner
tglx at linutronix.de
Fri Jan 11 10:52:54 EST 2013
On Fri, 11 Jan 2013, steve.zhan wrote:
> Resend Email because MUTT email send error.
>
> 2013/1/11 Steve zhan <zhanzhenbo at gmail.com>:
> > All:
> > I have find that arm gic driver have not register irq_disable
> > method, as below:
> > static struct irq_chip gic_chip = {
> > .name = "GIC",
> > .irq_mask = gic_mask_irq,
> > .irq_unmask = gic_unmask_irq,
> > .irq_eoi = gic_eoi_irq,
> > .irq_set_type = gic_set_type,
> > .irq_retrigger = gic_retrigger,
> > #ifdef CONFIG_SMP
> > .irq_set_affinity = gic_set_affinity,
> > #endif
> > .irq_set_wake = gic_set_wake,
> > };
> >
> > Question is:
> > When some drivers want to disable irq, maybe it will call
> > linux standard inerface: irq_disable() that defined in include\
> > linux\interrupt.h, this function will call
> > void irq_disable(struct irq_desc *desc)
> > {
> > irq_state_set_disabled(desc);
> > if (desc->irq_data.chip->irq_disable) {
> > desc->irq_data.chip->irq_disable(&desc->irq_data);
> > irq_state_set_masked(desc);
> > }
> > }
> >
> > Because gic have not register irq_diable method, so the interrupt can
> > not disable immediately, it is enable until the interrupt come next time,
> > then disalbed by mask because irq_state_set_disable(desc);
> >
> > I have checked irq_enable method:
> > void irq_enable(struct irq_desc *desc)
> > {
> > irq_state_clr_disabled(desc);
> > if (desc->irq_data.chip->irq_enable)
> > desc->irq_data.chip->irq_enable(&desc->irq_data);
> > else
> > desc->irq_data.chip->irq_unmask(&desc->irq_data);
> > irq_state_clr_masked(desc);
> > }
> > This method have do unmask when irq_enable method is not exist.
> >
> > Is it a good idea to add irq_mask call in irq_disable()?
No. It's a very bad idea. We intentionally disable interrupts lazy.
Thanks,
tglx
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