From: Chris Wilson <chris@chris-wilson.co.uk>
Date: Tue, 23 Jan 2018 21:04:12 +0000
Subject: drm/i915/execlists: Inhibit context save/restore for the fake preempt
context
Git-commit: 517aaffe0c1b54b4f732e872a89681c650d3527f
Patch-mainline: v4.17-rc1
References: FATE#326289 FATE#326079 FATE#326049 FATE#322398 FATE#326166
We only use the preempt context to inject an idle point into execlists.
We never need to reference its logical state, so tell the GPU never to
load it or save it.
v2: BIT(2) for save-inhibit.
N.B. Daniele mentioned this bit mbz for ICL, and has been moved into the
submission process rather than the context image.
Suggested-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Michal Winiarski <michal.winiarski@intel.com>
Cc: Michel Thierry <michel.thierry@intel.com>
Cc: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Reviewed-by: Michel Thierry <michel.thierry@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180123210412.17653-1-chris@chris-wilson.co.uk
Acked-by: Petr Tesarik <ptesarik@suse.com>
---
drivers/gpu/drm/i915/intel_lrc.c | 4 ++++
drivers/gpu/drm/i915/intel_lrc.h | 1 +
2 files changed, 5 insertions(+)
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -2242,6 +2242,10 @@ populate_lr_context(struct i915_gem_cont
if (!engine->default_state)
regs[CTX_CONTEXT_CONTROL + 1] |=
_MASKED_BIT_ENABLE(CTX_CTRL_ENGINE_CTX_RESTORE_INHIBIT);
+ if (ctx->hw_id == PREEMPT_ID)
+ regs[CTX_CONTEXT_CONTROL + 1] |=
+ _MASKED_BIT_ENABLE(CTX_CTRL_ENGINE_CTX_RESTORE_INHIBIT |
+ CTX_CTRL_ENGINE_CTX_SAVE_INHIBIT);
i915_gem_object_unpin_map(ctx_obj);
--- a/drivers/gpu/drm/i915/intel_lrc.h
+++ b/drivers/gpu/drm/i915/intel_lrc.h
@@ -37,6 +37,7 @@
#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 CTX_CTRL_ENGINE_CTX_SAVE_INHIBIT (1 << 2)
#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)