On 1/24/2018 12:46 PM, Chris Wilson wrote:
Quoting Chris Wilson (2018-01-24 09:44:45)
Quoting Michel Thierry (2018-01-24 01:24:25)
On 1/23/2018 1:04 PM, Chris Wilson wrote:
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@xxxxxxxxx>
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: Michal Winiarski <michal.winiarski@xxxxxxxxx>
Cc: Michel Thierry <michel.thierry@xxxxxxxxx>
Cc: Michal Wajdeczko <michal.wajdeczko@xxxxxxxxx>
Cc: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
Cc: Mika Kuoppala <mika.kuoppala@xxxxxxxxx>
Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@xxxxxxxxx>
---
drivers/gpu/drm/i915/intel_lrc.c | 4 ++++
drivers/gpu/drm/i915/intel_lrc.h | 1 +
2 files changed, 5 insertions(+)
diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index 22d471a4228d..c28f267a8417 100644
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -2285,6 +2285,10 @@ populate_lr_context(struct i915_gem_context *ctx,
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);
This shouldn't break anything and ICL is not merged yet (plus things may
still change) so if you want to merge this,
I think it's the right thing conceptually to do.
Uhoh, seeing GPU hangs on Broxton when thrashing preemption.
Is the bit still valid?
It should be valid, but nobody used cxt save inhibit until now (it
doesn't surprise bxt is doing something different).
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