[Intel-xe] [PATCH v2] drm/xe/tlb: fix expected_seqno calculation

[Matthew Auld]

It looks like when tlb_invalidation.seqno overflows
TLB_INVALIDATION_SEQNO_MAX, we start counting again from one, as per
send_tlb_invalidation(). This is also inline with initial value we give
it in xe_gt_tlb_invalidation_init().  When calculating the
expected_seqno we should also take this into account.

While we are here also print out the values if we ever trigger the
warning.

v2 (José):
  - drm_WARN_ON() is preferred over plain WARN_ON(), since it gives
    information on the originating device.

Closes: https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/248
Signed-off-by: Matthew Auld <matthew.auld at intel.com>
Cc: José Roberto de Souza <jose.souza at intel.com>
Reviewed-by: José Roberto de Souza <jose.souza at intel.com>
---
 drivers/gpu/drm/xe/xe_gt_tlb_invalidation.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/xe/xe_gt_tlb_invalidation.c b/drivers/gpu/drm/xe/xe_gt_tlb_invalidation.c
index f279e21300aa..604f189dbd70 100644
--- a/drivers/gpu/drm/xe/xe_gt_tlb_invalidation.c
+++ b/drivers/gpu/drm/xe/xe_gt_tlb_invalidation.c
@@ -319,7 +319,12 @@ int xe_guc_tlb_invalidation_done_handler(struct xe_guc *guc, u32 *msg, u32 len)
 	/* Sanity check on seqno */
 	expected_seqno = (gt->tlb_invalidation.seqno_recv + 1) %
 		TLB_INVALIDATION_SEQNO_MAX;
-	XE_WARN_ON(expected_seqno != msg[0]);
+	if (!expected_seqno)
+		expected_seqno = 1;
+	if (drm_WARN_ON(&gt->xe->drm, expected_seqno != msg[0])) {
+		drm_err(&gt->xe->drm, "TLB expected_seqno(%d) != msg(%u)\n",
+			expected_seqno, msg[0]);
+	}
 
 	gt->tlb_invalidation.seqno_recv = msg[0];
 	smp_wmb();
-- 
2.39.2