[Intel-gfx] [PATCH] drm/i915: Add temporary ring->ctx backpointer

[Daniel, Thomas]

> -----Original Message-----
> From: Daniel Vetter [mailto:daniel.vetter at ffwll.ch]
> Sent: Thursday, August 14, 2014 5:28 PM
> To: Intel Graphics Development
> Cc: Mateo Lozano, Oscar; Daniel, Thomas; Daniel Vetter
> Subject: [PATCH] drm/i915: Add temporary ring->ctx backpointer
> 
> From: Oscar Mateo <oscar.mateo at intel.com>
> 
> The execlist patches have a bit a convoluted and long history and due to that
> have the actual submission still misplaced deeply burried in the low-level
> ringbuffer handling code. This design goes back to the legacy ringbuffer code
> with its tricky lazy request and simple work submissiion using ring tail writes.
> For that reason they need a
> ring->ctx backpointer.
> 
> The goal is to unburry that code and move it up into a level where the full
> execlist context is available so that we can ditch this backpointer. Until that's
> done make it really obvious that there's work still to be done.
> 
> Cc: Oscar Mateo <oscar.mateo at intel.com>
> Cc: Thomas Daniel <thomas.daniel at intel.com>
> Signed-off-by: Daniel Vetter <daniel.vetter at ffwll.ch>
> 
> --
> 
> Thomas, please ack this patch and the general plan we've discussed.
Acked-by: Thomas Daniel <thomas.daniel at intel.com>

> Then I'll start pulling in more patches and I'll do the s/ctx/FIXME_lrc_ctx/ on
> the fly.
> -Daniel
> ---
>  drivers/gpu/drm/i915/intel_lrc.c        | 2 ++
>  drivers/gpu/drm/i915/intel_ringbuffer.h | 7 +++++++
>  2 files changed, 9 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/intel_lrc.c
> b/drivers/gpu/drm/i915/intel_lrc.c
> index 6b5f416b5c0d..c2352d1b23fa 100644
> --- a/drivers/gpu/drm/i915/intel_lrc.c
> +++ b/drivers/gpu/drm/i915/intel_lrc.c
> @@ -1086,6 +1086,8 @@ int intel_lr_context_deferred_create(struct
> intel_context *ctx,
>  	}
> 
>  	ringbuf->ring = ring;
> +	ringbuf->FIXME_lrc_ctx = ctx;
> +
>  	ringbuf->size = 32 * PAGE_SIZE;
>  	ringbuf->effective_size = ringbuf->size;
>  	ringbuf->head = 0;
> diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.h
> b/drivers/gpu/drm/i915/intel_ringbuffer.h
> index 24437da91f77..26785ca72530 100644
> --- a/drivers/gpu/drm/i915/intel_ringbuffer.h
> +++ b/drivers/gpu/drm/i915/intel_ringbuffer.h
> @@ -99,6 +99,13 @@ struct intel_ringbuffer {
> 
>  	struct intel_engine_cs *ring;
> 
> +	/*
> +	 * FIXME: This backpointer is an artifact of the history of how the
> +	 * execlist patches came into being. It will get removed once the basic
> +	 * code has landed.
> +	 */
> +	struct intel_context *FIXME_lrc_ctx;
> +
>  	u32 head;
>  	u32 tail;
>  	int space;
> --
> 2.0.1