Re: [PATCH 3/3] drm/i915/guc: Flush G2H handler during a GT reset

[John Harrison]

On 1/19/2022 13:24, Matthew Brost wrote:

Now that the error capture is fully decoupled from fence signalling
(request retirement to free memory, which in turn depends on resets) we
can safely flush the G2H handler during a GT reset. This is eliminates

This eliminates

John.

corner cases where GuC generated G2H (e.g. engine resets) race with a GT
reset.

v2:
  (John Harrison)
   - Fix typo in commit message (s/is/in)

Signed-off-by: Matthew Brost <matthew.br...@intel.com>
Reviewed-by: John Harrison <john.c.harri...@intel.com>
---
  .../gpu/drm/i915/gt/uc/intel_guc_submission.c  | 18 +-----------------
  1 file changed, 1 insertion(+), 17 deletions(-)

diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c 
b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
index 514b3060b141..406dd2e3f5a9 100644
--- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
+++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
@@ -1396,8 +1396,6 @@ static void guc_flush_destroyed_contexts(struct intel_guc 
*guc);

void intel_guc_submission_reset_prepare(struct intel_guc *guc)

  {
-       int i;
-
        if (unlikely(!guc_submission_initialized(guc))) {
                /* Reset called during driver load? GuC not yet initialised! */
                return;
@@ -1414,21 +1412,7 @@ void intel_guc_submission_reset_prepare(struct intel_guc 
*guc)

guc_flush_submissions(guc);

        guc_flush_destroyed_contexts(guc);
-
-       /*
-        * Handle any outstanding G2Hs before reset. Call IRQ handler directly
-        * each pass as interrupt have been disabled. We always scrub for
-        * outstanding G2H as it is possible for outstanding_submission_g2h to
-        * be incremented after the context state update.
-        */
-       for (i = 0; i < 4 && atomic_read(&guc->outstanding_submission_g2h); 
++i) {
-               intel_guc_to_host_event_handler(guc);
-#define wait_for_reset(guc, wait_var) \
-               intel_guc_wait_for_pending_msg(guc, wait_var, false, (HZ / 20))
-               do {
-                       wait_for_reset(guc, &guc->outstanding_submission_g2h);
-               } while (!list_empty(&guc->ct.requests.incoming));
-       }
+       flush_work(&guc->ct.requests.worker);

scrub_guc_desc_for_outstanding_g2h(guc);

  }