[Intel-gfx] [PATCH 1/2] drm/i915/gt: Skip global serialisation of clear_range for bxt vtd

[Mika Kuoppala]

Chris Wilson <chris at chris-wilson.co.uk> writes:

> VT'd on Broxton and on Braswell require serialisation of GGTT updates.
> However, it seems to only be required for insertion, so drop the
> complication and heavyweight stop_machine() for clears. The range will
> be serialised again before use.

This makes much sense.

>
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>


Reviewed-by: Mika Kuoppala <mika.kuoppala at linux.intel.com>

> ---
>  drivers/gpu/drm/i915/gt/intel_ggtt.c | 27 ---------------------------
>  1 file changed, 27 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/gt/intel_ggtt.c b/drivers/gpu/drm/i915/gt/intel_ggtt.c
> index 79096722ce16..81a63f7bc6c4 100644
> --- a/drivers/gpu/drm/i915/gt/intel_ggtt.c
> +++ b/drivers/gpu/drm/i915/gt/intel_ggtt.c
> @@ -350,31 +350,6 @@ static void bxt_vtd_ggtt_insert_entries__BKL(struct i915_address_space *vm,
>  	stop_machine(bxt_vtd_ggtt_insert_entries__cb, &arg, NULL);
>  }
>  
> -struct clear_range {
> -	struct i915_address_space *vm;
> -	u64 start;
> -	u64 length;
> -};
> -
> -static int bxt_vtd_ggtt_clear_range__cb(void *_arg)
> -{
> -	struct clear_range *arg = _arg;
> -
> -	gen8_ggtt_clear_range(arg->vm, arg->start, arg->length);
> -	bxt_vtd_ggtt_wa(arg->vm);
> -
> -	return 0;
> -}
> -
> -static void bxt_vtd_ggtt_clear_range__BKL(struct i915_address_space *vm,
> -					  u64 start,
> -					  u64 length)
> -{
> -	struct clear_range arg = { vm, start, length };
> -
> -	stop_machine(bxt_vtd_ggtt_clear_range__cb, &arg, NULL);
> -}
> -
>  static void gen6_ggtt_clear_range(struct i915_address_space *vm,
>  				  u64 start, u64 length)
>  {
> @@ -879,8 +854,6 @@ static int gen8_gmch_probe(struct i915_ggtt *ggtt)
>  	    IS_CHERRYVIEW(i915) /* fails with concurrent use/update */) {
>  		ggtt->vm.insert_entries = bxt_vtd_ggtt_insert_entries__BKL;
>  		ggtt->vm.insert_page    = bxt_vtd_ggtt_insert_page__BKL;
> -		if (ggtt->vm.clear_range != nop_clear_range)
> -			ggtt->vm.clear_range = bxt_vtd_ggtt_clear_range__BKL;
>  	}
>  
>  	ggtt->invalidate = gen8_ggtt_invalidate;
> -- 
> 2.25.0