[PATCH 6.18 280/752] octeontx2-af: Workaround SQM/PSE stalls by disabling sticky

Sasha Levin
2026-02-28T17:52:02Z

From: Geetha sowjanya <gakula@marvell.com>

[ Upstream commit 70e9a5760abfb6338d63994d4de6b0778ec795d6 ]

NIX SQ manager sticky mode is known to cause stalls when multiple SQs
share an SMQ and transmit concurrently. Additionally, PSE may deadlock
on transitions between sticky and non-sticky transmissions. There is
also a credit drop issue observed when certain condition clocks are
gated.

work around these hardware errata by:
- Disabling SQM sticky operation:
- Clear TM6 (bit 15)
- Clear TM11 (bit 14)
- Disabling sticky → non-sticky transition path that can deadlock PSE:
- Clear TM5 (bit 23)
- Preventing credit drops by keeping the control-flow clock enabled:
- Set TM9 (bit 21)

These changes are applied via NIX_AF_SQM_DBG_CTL_STATUS. With this
configuration the SQM/PSE maintain forward progress under load without
credit loss, at the cost of disabling sticky optimizations.

Signed-off-by: Geetha sowjanya <gakula@marvell.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20260127125147.1642-1-gakula@marvell.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/net/ethernet/marvell/octeontx2/af/rvu_nix.c | 12 +++++++++---
1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/marvell/octeontx2/af/rvu_nix.c b/drivers/net/ethernet/marvell/octeontx2/af/rvu_nix.c
index 828316211b245..c9c65ac69ead8 100644
--- a/drivers/net/ethernet/marvell/octeontx2/af/rvu_nix.c
+++ b/drivers/net/ethernet/marvell/octeontx2/af/rvu_nix.c
@@ -4932,12 +4932,18 @@ static int rvu_nix_block_init(struct rvu *rvu, struct nix_hw *nix_hw)
/* Set chan/link to backpressure TL3 instead of TL2 */
rvu_write64(rvu, blkaddr, NIX_AF_PSE_CHANNEL_LEVEL, 0x01);

- /* Disable SQ manager's sticky mode operation (set TM6 = 0)
+ /* Disable SQ manager's sticky mode operation (set TM6 = 0, TM11 = 0)
* This sticky mode is known to cause SQ stalls when multiple
- * SQs are mapped to same SMQ and transmitting pkts at a time.
+ * SQs are mapped to same SMQ and transmitting pkts simultaneously.
+ * NIX PSE may deadlock when there are any sticky to non-sticky
+ * transmission. Hence disable it (TM5 = 0).
*/
cfg = rvu_read64(rvu, blkaddr, NIX_AF_SQM_DBG_CTL_STATUS);
- cfg &= ~BIT_ULL(15);
+ cfg &= ~(BIT_ULL(15) | BIT_ULL(14) | BIT_ULL(23));
+ /* NIX may drop credits when condition clocks are turned off.
+ * Hence enable control flow clk (set TM9 = 1).
+ */
+ cfg |= BIT_ULL(21);
rvu_write64(rvu, blkaddr, NIX_AF_SQM_DBG_CTL_STATUS, cfg);

ltdefs = rvu->kpu.lt_def;
--
2.51.0