[Intel-gfx] [PATCH 09/10] drm/i915/icl: Handle display interrupts after enabling master

[Chris Wilson]

Quoting Mika Kuoppala (2018-09-20 15:33:49)
> Don't keep master disabled while handling display interrupts.
> This should help a little with latency of generating the
> next interrupt.
> 
> Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
> Cc: Chris Wilson <chris at chris-wilson.co.uk>
> Signed-off-by: Mika Kuoppala <mika.kuoppala at linux.intel.com>
> ---
>  drivers/gpu/drm/i915/i915_irq.c | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
> index b4992d397c5d..27116e3f21af 100644
> --- a/drivers/gpu/drm/i915/i915_irq.c
> +++ b/drivers/gpu/drm/i915/i915_irq.c
> @@ -3162,13 +3162,11 @@ static irqreturn_t gen11_irq_handler(int irq, void *arg)
>                 return IRQ_NONE;
>  
>         master_ctl = gen11_master_irq_disable(regs);
> -
> -       gen11_display_irq_handler(i915, master_ctl);
>         gu_misc_iir = gen11_gu_misc_irq_ack(regs, master_ctl);
> -
>         gen11_master_irq_enable(regs);
>  
>         gen11_gt_irq_handler(i915, master_ctl);
> +       gen11_display_irq_handler(i915, master_ctl);
>         gen11_gu_misc_irq_handler(i915, gu_misc_iir);

Hmm. So we no longer do ack within the interrupts off section. Is there
even a point to disabling master-ctl in that scenario. The danger is
simply we raise more master interrupts for sub-level interrupts that we
proceed to handle. Doesn't seem like a huge deal... But there's usually
some interesting rules on edge level interrupt that bite.
-Chris