[Intel-gfx] [PATCH 03/39] drm/i915: Explicit power enable during deferred context initialisation

[Joonas Lahtinen]

On ma, 2015-11-23 at 11:38 +0000, John.C.Harrison at Intel.com wrote:
> From: John Harrison <John.C.Harrison at Intel.com>
> 
> A later patch in this series re-organises the batch buffer submission
> code. Part of that is to reduce the scope of a pm_get/put pair.
> Specifically, they previously wrapped the entire submission path from
> the very start to the very end, now they only wrap the actual
> hardware
> submission part in the back half.
> 
> While that is a good thing in general, it causes a problem with the
> deferred context initialisation. That is done quite early on in the
> execbuf code path - it happens at context validation time rather than
> context switch time. Some of the deferred work requires the power to
> be enabled. Hence this patch adds an explicit power reference count
> to
> the deferred initialisation code itself.
> 
> Change-Id: Id7b1535dfd8809a2bd5546272de2bbec39da2868
> Issue: GMINL-5159

Reviewed-by: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>

> Signed-off-by: John Harrison <John.C.Harrison at Intel.com>
> ---
>  drivers/gpu/drm/i915/intel_lrc.c | 9 ++++++++-
>  1 file changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_lrc.c
> b/drivers/gpu/drm/i915/intel_lrc.c
> index 76fc245..e510730 100644
> --- a/drivers/gpu/drm/i915/intel_lrc.c
> +++ b/drivers/gpu/drm/i915/intel_lrc.c
> @@ -2470,6 +2470,8 @@ int intel_lr_context_deferred_alloc(struct
> intel_context *ctx,
>  	WARN_ON(ctx->legacy_hw_ctx.rcs_state != NULL);
>  	WARN_ON(ctx->engine[ring->id].state);
>  
> +	intel_runtime_pm_get(dev->dev_private);
> +
>  	context_size = round_up(get_lr_context_size(ring), 4096);
>  
>  	/* One extra page as the sharing data between driver and GuC
> */
> @@ -2478,7 +2480,8 @@ int intel_lr_context_deferred_alloc(struct
> intel_context *ctx,
>  	ctx_obj = i915_gem_alloc_object(dev, context_size);
>  	if (!ctx_obj) {
>  		DRM_DEBUG_DRIVER("Alloc LRC backing obj failed.\n");
> -		return -ENOMEM;
> +		ret = -ENOMEM;
> +		goto error_pm;
>  	}
>  
>  	ringbuf = intel_engine_create_ringbuffer(ring, 4 *
> PAGE_SIZE);
> @@ -2524,6 +2527,8 @@ int intel_lr_context_deferred_alloc(struct
> intel_context *ctx,
>  		}
>  		i915_add_request_no_flush(req);
>  	}
> +
> +	intel_runtime_pm_put(dev->dev_private);
>  	return 0;
>  
>  error_ringbuf:
> @@ -2532,6 +2537,8 @@ error_deref_obj:
>  	drm_gem_object_unreference(&ctx_obj->base);
>  	ctx->engine[ring->id].ringbuf = NULL;
>  	ctx->engine[ring->id].state = NULL;
> +error_pm:
> +	intel_runtime_pm_put(dev->dev_private);
>  	return ret;
>  }
>  
-- 
Joonas Lahtinen
Open Source Technology Center
Intel Corporation