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    SubjectRe: [Intel-gfx] [PATCH] drm/i915: Remove unused IRQ chip data of HDMI LPE audio
    On Fri, 8 Dec 2017, Ville Syrjälä wrote:

    > On Fri, Dec 08, 2017 at 05:33:23PM +0800, Augustine.Chen wrote:
    > > The chip data of HDMI LPE audio is set to drm_i915_private which is not
    > > consistent with the expectation by x86 APIC driver.
    >
    > Hmm. Why is the apic code looking at data for an irq chip it
    > hasn't created?
    >
    > Do we need something like
    > - dev_priv->lpe_audio.irq = irq_alloc_desc(0);
    > + dev_priv->lpe_audio.irq = irq_alloc_desc(-1);

    #define irq_alloc_desc(node)

    So instead of handing in node 0 you hand in node -1 which is NUMA_NO_NODE

    > That *looks* more correct to me based on a cursory glance at the x86
    > code, but I didn't trawl very deeply.

    The x86 core cares not at all about interrupt chips which are created in a
    driver and not connected to an actual apic/ioapic/msi interrupt. This
    interrupt chip is its own thing as we have others in GPIO etc.

    > > In the case of not enabling CONFIG_CPUMASK_OFFSTACK, this would cause
    > > kernel panic while doing CPU hotplug.

    And why so? Surely not because you set irq_chip_data. That's really no
    explanation at all.

    Curing the symptom is never a good approach.

    Thanks,

    tglx
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