[RFC 03/39] drm/i915: Explicit power enable during deferred context initialisation

John.C.Harrison
2015-07-17T14:33:54Z

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
Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
---
drivers/gpu/drm/i915/intel_lrc.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index 18dbd5c..8aa9a18 100644
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -2317,12 +2317,15 @@ int intel_lr_context_deferred_create(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);

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;
}

if (is_global_default_ctx) {
@@ -2331,7 +2334,7 @@ int intel_lr_context_deferred_create(struct intel_context *ctx,
DRM_DEBUG_DRIVER("Pin LRC backing obj failed: %d\n",
ret);
drm_gem_object_unreference(&ctx_obj->base);
- return ret;
+ goto error_pm;
}
}

@@ -2415,6 +2418,7 @@ int intel_lr_context_deferred_create(struct intel_context *ctx,
ctx->rcs_initialized = true;
}

+ intel_runtime_pm_put(dev->dev_private);
return 0;

error:
@@ -2428,6 +2432,8 @@ error_unpin_ctx:
if (is_global_default_ctx)
i915_gem_object_ggtt_unpin(ctx_obj);
drm_gem_object_unreference(&ctx_obj->base);
+error_pm:
+ intel_runtime_pm_put(dev->dev_private);
return ret;