From: Chris Wilson <chris@chris-wilson.co.uk>
Date: Wed, 21 Feb 2018 13:32:36 +0000
Subject: drm/i915/execlists: Remove the ring advancement under preemption
Git-commit: 561210706cd00f83f14af124edb3a5ff1b732912
Patch-mainline: v4.17-rc1
References: FATE#326289 FATE#326079 FATE#326049 FATE#322398 FATE#326166
Load an empty ringbuffer for preemption, ignoring the lite-restore
workaround as we know the preempt context is always idle before preemption.
Note that after some digging by Michal Winiarski, we found that
RING_HEAD is no longer being updated (due to inhibiting context save
restore) so this patch is already in effect!
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>
Reviewed-by: Michel Thierry <michel.thierry@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180221133236.29402-1-chris@chris-wilson.co.uk
Acked-by: Petr Tesarik <ptesarik@suse.com>
---
drivers/gpu/drm/i915/intel_lrc.c | 7 -------
1 file changed, 7 deletions(-)
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -447,13 +447,6 @@ static void inject_preempt_context(struc
GEM_BUG_ON(engine->execlists.preempt_complete_status !=
upper_32_bits(ce->lrc_desc));
- GEM_BUG_ON(!IS_ALIGNED(ce->ring->size, WA_TAIL_BYTES));
-
- memset(ce->ring->vaddr + ce->ring->tail, 0, WA_TAIL_BYTES);
- ce->ring->tail += WA_TAIL_BYTES;
- ce->ring->tail &= (ce->ring->size - 1);
- ce->lrc_reg_state[CTX_RING_TAIL+1] = ce->ring->tail;
-
GEM_BUG_ON((ce->lrc_reg_state[CTX_CONTEXT_CONTROL + 1] &
_MASKED_BIT_ENABLE(CTX_CTRL_ENGINE_CTX_RESTORE_INHIBIT |
CTX_CTRL_ENGINE_CTX_SAVE_INHIBIT)) !=