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In the current scheme, on submitting a request we take a single global GEM wakeref, which trickles down to wake up all GT power domains. This is undesirable as we would like to be able to localise our power management to the available power domains and to remove the global GEM operations from the heart of the driver. (The intent there is to push global GEM decisions to the boundary as used by the GEM user interface.) Now during request construction, each request is responsible via its logical context to acquire a wakeref on each power domain it intends to utilize. Currently, each request takes a wakeref on the engine(s) and the engines themselves take a chipset wakeref. This gives us a transition on each engine which we can extend if we want to insert more powermangement control (such as soft rc6). The global GEM operations that currently require a struct_mutex are reduced to listening to pm events from the chipset GT wakeref. As we reduce the struct_mutex requirement, these listeners should evaporate. Perhaps the biggest immediate change is that this removes the struct_mutex requirement around GT power management, allowing us greater flexibility in request construction. Another important knock-on effect, is that by tracking engine usage, we can insert a switch back to the kernel context on that engine immediately, avoiding any extra delay or inserting global synchronisation barriers. This makes tracking when an engine and its associated contexts are idle much easier -- important for when we forgo our assumed execution ordering and need idle barriers to unpin used contexts. In the process, it means we remove a large chunk of code whose only purpose was to switch back to the kernel context. Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com> Cc: Imre Deak <imre.deak@intel.com> Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20190424200717.1686-5-chris@chris-wilson.co.uk
25 lines
587 B
C
25 lines
587 B
C
/*
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* SPDX-License-Identifier: MIT
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*
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* Copyright © 2019 Intel Corporation
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*/
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#ifndef __I915_GEM_PM_H__
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#define __I915_GEM_PM_H__
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#include <linux/types.h>
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struct drm_i915_private;
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struct work_struct;
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void i915_gem_init__pm(struct drm_i915_private *i915);
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bool i915_gem_load_power_context(struct drm_i915_private *i915);
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void i915_gem_resume(struct drm_i915_private *i915);
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void i915_gem_idle_work_handler(struct work_struct *work);
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void i915_gem_suspend(struct drm_i915_private *i915);
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void i915_gem_suspend_late(struct drm_i915_private *i915);
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#endif /* __I915_GEM_PM_H__ */
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