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

[Jike Song]

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.


>
> Thanks
> Kevin
>

--
Thanks,
Jike