[Intel-gfx] i915 irq storm mitigation in 3.10

[Jan Niggemann]

Hi Daniel,

Am 25.07.2013 11:58, schrieb Daniel Vetter:
> Can you pls try the below
> patch (on top of Egbert's debug stuff)?
>
> diff --git a/drivers/gpu/drm/i915/i915_reg.h
> b/drivers/gpu/drm/i915/i915_reg.h
> index 6caa748..2d4c884 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -1925,9 +1925,9 @@
>
>  #define PORT_HOTPLUG_STAT      (dev_priv->info->display_mmio_offset
> + 0x61114)
>  /* HDMI/DP bits are gen4+ */
> -#define   PORTB_HOTPLUG_LIVE_STATUS               (1 << 29)
> +#define   PORTD_HOTPLUG_LIVE_STATUS               (1 << 29)
>  #define   PORTC_HOTPLUG_LIVE_STATUS               (1 << 28)
> -#define   PORTD_HOTPLUG_LIVE_STATUS               (1 << 27)
> +#define   PORTB_HOTPLUG_LIVE_STATUS               (1 << 27)
>  #define   PORTD_HOTPLUG_INT_STATUS             (3 << 21)
>  #define   PORTC_HOTPLUG_INT_STATUS             (3 << 19)
>  #define   PORTB_HOTPLUG_INT_STATUS             (3 << 17)
I did, here are the logs:
364K http://files.hz6.de/kern_20130724_2.log
I don't understand what exactly this patch does, but I noticed:
- much less drm debug info, resulting in a much smaller log
- no more noticeable lag on my system (even though a storm was 
detected).
I double checked the latter and the lag seems indeed to be gone...

Jan