[PATCH v4 02/38] drm/i915: Explicit power enable during deferred context initialisation

John.C.Harrison
2016-01-11T18:43:12Z

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.

Issue: GMINL-5159
Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.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;