Re: [Intel-gfx] [PATCH 11/25] drm/i915/guc: Implement parallel context pin / unpin functions

[John Harrison <john.c.harrison@intel.com>]

On 10/13/2021 13:42, Matthew Brost wrote:
> Parallel contexts are perma-pinned by the upper layers which makes the
> backend implementation rather simple. The parent pins the guc_id and
> children increment the parent's pin count on pin to ensure all the
> contexts are unpinned before we disable scheduling with the GuC / or
> deregister the context.
>
> v2:
>   (Daniel Vetter)
>    - Perma-pin parallel contexts
>
> Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: John Harrison <John.C.Harrison@Intel.com>

> ---
>   .../gpu/drm/i915/gt/uc/intel_guc_submission.c | 70 +++++++++++++++++++
>   1 file changed, 70 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> index c4d7a5c3b558..9fc40e3c1794 100644
> --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> @@ -2585,6 +2585,76 @@ static const struct intel_context_ops virtual_guc_context_ops = {
>   	.get_sibling = guc_virtual_get_sibling,
>   };
>   
> +/* Future patches will use this function */
> +__maybe_unused
> +static int guc_parent_context_pin(struct intel_context *ce, void *vaddr)
> +{
> +	struct intel_engine_cs *engine = guc_virtual_get_sibling(ce->engine, 0);
> +	struct intel_guc *guc = ce_to_guc(ce);
> +	int ret;
> +
> +	GEM_BUG_ON(!intel_context_is_parent(ce));
> +	GEM_BUG_ON(!intel_engine_is_virtual(ce->engine));
> +
> +	ret = pin_guc_id(guc, ce);
> +	if (unlikely(ret < 0))
> +		return ret;
> +
> +	return __guc_context_pin(ce, engine, vaddr);
> +}
> +
> +/* Future patches will use this function */
> +__maybe_unused
> +static int guc_child_context_pin(struct intel_context *ce, void *vaddr)
> +{
> +	struct intel_engine_cs *engine = guc_virtual_get_sibling(ce->engine, 0);
> +
> +	GEM_BUG_ON(!intel_context_is_child(ce));
> +	GEM_BUG_ON(!intel_engine_is_virtual(ce->engine));
> +
> +	__intel_context_pin(ce->parallel.parent);
> +	return __guc_context_pin(ce, engine, vaddr);
> +}
> +
> +/* Future patches will use this function */
> +__maybe_unused
> +static void guc_parent_context_unpin(struct intel_context *ce)
> +{
> +	struct intel_guc *guc = ce_to_guc(ce);
> +
> +	GEM_BUG_ON(context_enabled(ce));
> +	GEM_BUG_ON(intel_context_is_barrier(ce));
> +	GEM_BUG_ON(!intel_context_is_parent(ce));
> +	GEM_BUG_ON(!intel_engine_is_virtual(ce->engine));
> +
> +	unpin_guc_id(guc, ce);
> +	lrc_unpin(ce);
> +}
> +
> +/* Future patches will use this function */
> +__maybe_unused
> +static void guc_child_context_unpin(struct intel_context *ce)
> +{
> +	GEM_BUG_ON(context_enabled(ce));
> +	GEM_BUG_ON(intel_context_is_barrier(ce));
> +	GEM_BUG_ON(!intel_context_is_child(ce));
> +	GEM_BUG_ON(!intel_engine_is_virtual(ce->engine));
> +
> +	lrc_unpin(ce);
> +}
> +
> +/* Future patches will use this function */
> +__maybe_unused
> +static void guc_child_context_post_unpin(struct intel_context *ce)
> +{
> +	GEM_BUG_ON(!intel_context_is_child(ce));
> +	GEM_BUG_ON(!intel_context_is_pinned(ce->parallel.parent));
> +	GEM_BUG_ON(!intel_engine_is_virtual(ce->engine));
> +
> +	lrc_post_unpin(ce);
> +	intel_context_unpin(ce->parallel.parent);
> +}
> +
>   static bool
>   guc_irq_enable_breadcrumbs(struct intel_breadcrumbs *b)
>   {