Re: [PATCH] drm/i915: rip out the HWSTAM missed irq workaround

[Ben Widawsky <ben@bwidawsk.net>]

On Thu, Jan 05, 2012 at 11:11:53PM +0100, Daniel Vetter wrote:
> With the new ducttape of much finer quality, this seems to be no
> longer necessary.
> 
> Tested on my ivb and snb machine with the usual suspects of testcases.
> 
> Signed-Off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
> ---
>  drivers/gpu/drm/i915/i915_irq.c |   11 -----------
>  1 files changed, 0 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
> index b9ba180..af54153 100644
> --- a/drivers/gpu/drm/i915/i915_irq.c
> +++ b/drivers/gpu/drm/i915/i915_irq.c
> @@ -1779,17 +1779,6 @@ static void ironlake_irq_preinstall(struct drm_device *dev)
>  		INIT_WORK(&dev_priv->rps_work, gen6_pm_rps_work);
>  
>  	I915_WRITE(HWSTAM, 0xeffe);
> -	if (IS_GEN6(dev) || IS_GEN7(dev)) {
> -		/* Workaround stalls observed on Sandy Bridge GPUs by
> -		 * making the blitter command streamer generate a
> -		 * write to the Hardware Status Page for
> -		 * MI_USER_INTERRUPT.  This appears to serialize the
> -		 * previous seqno write out before the interrupt
> -		 * happens.
> -		 */
> -		I915_WRITE(GEN6_BLITTER_HWSTAM, ~GEN6_BLITTER_USER_INTERRUPT);
> -		I915_WRITE(GEN6_BSD_HWSTAM, ~GEN6_BSD_USER_INTERRUPT);
> -	}
>  
>  	/* XXX hotplug from PCH */
>  


I'd prefer just reverting the old commits instead of this, but that's
just me.

Reviewed-and-Tested-by: Ben Widawsky <ben@bwidawsk.net>