Re: [PATCH 09/10] drm/i915/bdw: Always issue a force restore

[Ben Widawsky <benjamin.widawsky@intel.com>]

On Thu, Jul 03, 2014 at 05:33:05PM -0400, Rodrigo Vivi wrote:
> From: Ben Widawsky <benjamin.widawsky@intel.com>
> 
> The PDPs seem to get screwed up otherwise, specifically PDP0. I am not
> really clear why this is required, it just works with full PPGTT.
> 
> v2: Only do it for gen8, to limit regression potential
> 
> v3: Fix the bugzilla links
> 
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=78891
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=78935
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=78936
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=78937
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=78938
> 
> Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
> Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
> ---
>  drivers/gpu/drm/i915/i915_gem_context.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c
> index 633e318..61b60b6 100644
> --- a/drivers/gpu/drm/i915/i915_gem_context.c
> +++ b/drivers/gpu/drm/i915/i915_gem_context.c
> @@ -573,6 +573,9 @@ mi_set_context(struct intel_engine_cs *ring,
>  	else
>  		intel_ring_emit(ring, MI_NOOP);
>  
> +	if (INTEL_INFO(ring->dev)->gen == 8)
> +		hw_flags |= MI_FORCE_RESTORE;
> +
>  	intel_ring_emit(ring, MI_NOOP);
>  	intel_ring_emit(ring, MI_SET_CONTEXT);
>  	intel_ring_emit(ring,

Ville had a good point on this patch wrt to note setting both
MI_FORCE_RESTORE, and MI_RESTORE_INHIBIT (though it seems to cause no
problems).

I think also with some of the do_switch() cleanups recently submitted,
this one may no longer be necessary - not sure.

-- 
Ben Widawsky, Intel Open Source Technology Center