Upon a GPU reset, we copy the default context image over top of the
guilty image. This will rollback the CTX_TIMESTAMP register to before
our value of ce->runtime.last. Reset both back to 0 so that we do not
encounter an underflow on the next schedule out after resume.
This should not be a huge issue in practice, as hangs should be rare in
correct code.
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
---
drivers/gpu/drm/i915/gt/intel_lrc.c | 24 +++++++++++++-----------
1 file changed, 13 insertions(+), 11 deletions(-)
diff --git a/drivers/gpu/drm/i915/gt/intel_lrc.c b/drivers/gpu/drm/i915/gt/intel_lrc.c
index 9104796673dc..d53078b345be 100644
--- a/drivers/gpu/drm/i915/gt/intel_lrc.c
+++ b/drivers/gpu/drm/i915/gt/intel_lrc.c
@@ -238,6 +238,17 @@ __execlists_update_reg_state(const struct intel_context *ce,
const struct intel_engine_cs *engine,
u32 head);
+static u32 intel_context_get_runtime(const struct intel_context *ce)
+{
+ /*
+ * We can use either ppHWSP[16] which is recorded before the context
+ * switch (and so excludes the cost of context switches) or use the
+ * value from the context image itself, which is saved/restored earlier
+ * and so includes the cost of the save.
+ */
+ return READ_ONCE(ce->lrc_reg_state[CTX_TIMESTAMP]);
+}
+
static void mark_eio(struct i915_request *rq)
{
if (i915_request_completed(rq))
@@ -1154,6 +1165,7 @@ static void restore_default_state(struct intel_context *ce,
engine->context_size - PAGE_SIZE);
execlists_init_reg_state(regs, ce, engine, ce->ring, false);
+ ce->runtime.last = intel_context_get_runtime(ce);
}
static void reset_active(struct i915_request *rq,
@@ -1195,17 +1207,6 @@ static void reset_active(struct i915_request *rq,
ce->lrc_desc |= CTX_DESC_FORCE_RESTORE;
}
-static u32 intel_context_get_runtime(const struct intel_context *ce)
-{
- /*
- * We can use either ppHWSP[16] which is recorded before the context
- * switch (and so excludes the cost of context switches) or use the
- * value from the context image itself, which is saved/restored earlier
- * and so includes the cost of the save.
- */
- return READ_ONCE(ce->lrc_reg_state[CTX_TIMESTAMP]);
-}
-
static void st_update_runtime_underflow(struct intel_context *ce, s32 dt)
{
#if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
@@ -4601,6 +4602,7 @@ static void init_common_reg_state(u32 * const regs,
regs[CTX_CONTEXT_CONTROL] = ctl;
regs[CTX_RING_CTL] = RING_CTL_SIZE(ring->size) | RING_VALID;
+ regs[CTX_TIMESTAMP] = 0;
}
static void init_wa_bb_reg_state(u32 * const regs,
--
2.20.1
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