drm/i915: Add per ctx batchbuffer wa for timestamp

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Restoration of a previous timestamp can collide
with updating the timestamp, causing a value corruption.

Combat this issue by using indirect ctx bb to
modify the context image during restoring process.

We can preload value into scratch register. From which
we then do the actual write with LRR. LRR is faster and
thus less error prone as probability of race drops.

v2: tidying (Chris)
v3: lrr for all engines
v4: grp
v5: reg bit
v6: wa_bb_offset, virtual engines (Chris)

References: HSDES#16010904313
Testcase: igt/i915_selftest/gt_lrc
Suggested-by: Joseph Koston <joseph.koston@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Acked-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20200424230546.30271-1-mika.kuoppala@linux.intel.com

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Mika Kuoppala 2020-04-25 02:05:46 +03:00 • committed by Chris Wilson

parent 168c6d231b

commit 685d21096f

3 changed files with 125 additions and 13 deletions

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2

drivers/gpu/drm/i915/gt/intel_context_types.h

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3

drivers/gpu/drm/i915/gt/intel_gpu_commands.h

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133

drivers/gpu/drm/i915/gt/intel_lrc.c

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