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linux-next/drivers/gpu/drm/i915/intel_lrc.h
Chris Wilson e8a9c58fcd drm/i915: Unify active context tracking between legacy/execlists/guc
The requests conversion introduced a nasty bug where we could generate a
new request in the middle of constructing a request if we needed to idle
the system in order to evict space for a context. The request to idle
would be executed (and waited upon) before the current one, creating a
minor havoc in the seqno accounting, as we will consider the current
request to already be completed (prior to deferred seqno assignment) but
ring->last_retired_head would have been updated and still could allow
us to overwrite the current request before execution.

We also employed two different mechanisms to track the active context
until it was switched out. The legacy method allowed for waiting upon an
active context (it could forcibly evict any vma, including context's),
but the execlists method took a step backwards by pinning the vma for
the entire active lifespan of the context (the only way to evict was to
idle the entire GPU, not individual contexts). However, to circumvent
the tricky issue of locking (i.e. we cannot take struct_mutex at the
time of i915_gem_request_submit(), where we would want to move the
previous context onto the active tracker and unpin it), we take the
execlists approach and keep the contexts pinned until retirement.
The benefit of the execlists approach, more important for execlists than
legacy, was the reduction in work in pinning the context for each
request - as the context was kept pinned until idle, it could short
circuit the pinning for all active contexts.

We introduce new engine vfuncs to pin and unpin the context
respectively. The context is pinned at the start of the request, and
only unpinned when the following request is retired (this ensures that
the context is idle and coherent in main memory before we unpin it). We
move the engine->last_context tracking into the retirement itself
(rather than during request submission) in order to allow the submission
to be reordered or unwound without undue difficultly.

And finally an ulterior motive for unifying context handling was to
prepare for mock requests.

v2: Rename to last_retired_context, split out legacy_context tracking
for MI_SET_CONTEXT.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20161218153724.8439-3-chris@chris-wilson.co.uk
2016-12-18 16:18:50 +00:00

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C

/*
* Copyright © 2014 Intel Corporation
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice (including the next
* paragraph) shall be included in all copies or substantial portions of the
* Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
* DEALINGS IN THE SOFTWARE.
*/
#ifndef _INTEL_LRC_H_
#define _INTEL_LRC_H_
#include "intel_ringbuffer.h"
#define GEN8_LR_CONTEXT_ALIGN 4096
/* Execlists regs */
#define RING_ELSP(engine) _MMIO((engine)->mmio_base + 0x230)
#define RING_EXECLIST_STATUS_LO(engine) _MMIO((engine)->mmio_base + 0x234)
#define RING_EXECLIST_STATUS_HI(engine) _MMIO((engine)->mmio_base + 0x234 + 4)
#define RING_CONTEXT_CONTROL(engine) _MMIO((engine)->mmio_base + 0x244)
#define CTX_CTRL_INHIBIT_SYN_CTX_SWITCH (1 << 3)
#define CTX_CTRL_ENGINE_CTX_RESTORE_INHIBIT (1 << 0)
#define CTX_CTRL_RS_CTX_ENABLE (1 << 1)
#define RING_CONTEXT_STATUS_BUF_BASE(engine) _MMIO((engine)->mmio_base + 0x370)
#define RING_CONTEXT_STATUS_BUF_LO(engine, i) _MMIO((engine)->mmio_base + 0x370 + (i) * 8)
#define RING_CONTEXT_STATUS_BUF_HI(engine, i) _MMIO((engine)->mmio_base + 0x370 + (i) * 8 + 4)
#define RING_CONTEXT_STATUS_PTR(engine) _MMIO((engine)->mmio_base + 0x3a0)
/* The docs specify that the write pointer wraps around after 5h, "After status
* is written out to the last available status QW at offset 5h, this pointer
* wraps to 0."
*
* Therefore, one must infer than even though there are 3 bits available, 6 and
* 7 appear to be * reserved.
*/
#define GEN8_CSB_ENTRIES 6
#define GEN8_CSB_PTR_MASK 0x7
#define GEN8_CSB_READ_PTR_MASK (GEN8_CSB_PTR_MASK << 8)
#define GEN8_CSB_WRITE_PTR_MASK (GEN8_CSB_PTR_MASK << 0)
#define GEN8_CSB_WRITE_PTR(csb_status) \
(((csb_status) & GEN8_CSB_WRITE_PTR_MASK) >> 0)
#define GEN8_CSB_READ_PTR(csb_status) \
(((csb_status) & GEN8_CSB_READ_PTR_MASK) >> 8)
enum {
INTEL_CONTEXT_SCHEDULE_IN = 0,
INTEL_CONTEXT_SCHEDULE_OUT,
};
/* Logical Rings */
int intel_logical_ring_alloc_request_extras(struct drm_i915_gem_request *request);
int intel_logical_ring_reserve_space(struct drm_i915_gem_request *request);
void intel_logical_ring_stop(struct intel_engine_cs *engine);
void intel_logical_ring_cleanup(struct intel_engine_cs *engine);
int logical_render_ring_init(struct intel_engine_cs *engine);
int logical_xcs_ring_init(struct intel_engine_cs *engine);
int intel_engines_init(struct drm_i915_private *dev_priv);
/* Logical Ring Contexts */
/* One extra page is added before LRC for GuC as shared data */
#define LRC_GUCSHR_PN (0)
#define LRC_PPHWSP_PN (LRC_GUCSHR_PN + 1)
#define LRC_STATE_PN (LRC_PPHWSP_PN + 1)
struct drm_i915_private;
struct i915_gem_context;
uint32_t intel_lr_context_size(struct intel_engine_cs *engine);
void intel_lr_context_resume(struct drm_i915_private *dev_priv);
uint64_t intel_lr_context_descriptor(struct i915_gem_context *ctx,
struct intel_engine_cs *engine);
/* Execlists */
int intel_sanitize_enable_execlists(struct drm_i915_private *dev_priv,
int enable_execlists);
void intel_execlists_enable_submission(struct drm_i915_private *dev_priv);
bool intel_execlists_idle(struct drm_i915_private *dev_priv);
#endif /* _INTEL_LRC_H_ */