[Intel-gfx] [RFC PATCH 7/8] drm/i915: vgt irq mediation - via a tasklet based mechanism

[Tian, Kevin]

> From: Song, Jike
> Sent: Wednesday, October 22, 2014 3:35 PM
> 
> On 10/01/2014 12:26 AM, Tian, Kevin wrote:
> >  From virtualization p.o.v, the ideal case is to run host i915 irq handler in
> the
> > interrupt context, which meets all the assumption from original code. Using
> > tasklet or other manner still has some restriction. This is a major open we'd
> > like to hear more from you guys. Is it possible to have i915 driver to request
> > two irq numbers: irq1 for real device and irq2 is purely faked one. vgt
> handler
> > registers on irq1 and i915 hanlder registers on irq2, and then we can use self
> > IPI to trigger irq2 when injection is required. But I'm not sure whether this is
> > an existing feature in kernel, or need some core enhancement in irq
> sub-system...
> 
> Hi Kevin, Daniel,
> 
>   I'm so excited to know that, there is an existing feature in kernel: irq_work.
> Basicly it allows us to run the host i915 ISR in hardirq context prefectly, what's
> needed is to select CONFIG_IRQ_WORK in Kconfig :)
> 
>   I'll use that in the v2 patches.
> 

Sounds like a better option. :-)

Thanks
Kevin