[PATCH net] net: airoha: Add retry mechanism to airoha_qdma_set_trtcm_param()

[Lorenzo Bianconi]

From: Brown Huang <brown.huang at airoha.com>

CPU accesses QDMA via the bus. When multiple modules are using the bus
simultaneously, CPU access to QDMA may encounter bus timeouts and fails,
resulting in QDMA configuration failures and potentially causing packet
transmission issues. In order to mitigate the issue, introduce a retry
mechanism to airoha_qdma_set_trtcm_param routine in order to ensure the
configuration is correctly applied to the hardware.

Fixes: ef1ca9271313b ("net: airoha: Add sched HTB offload support")
Signed-off-by: Brown Huang <brown.huang at airoha.com>
Signed-off-by: Lorenzo Bianconi <lorenzo at kernel.org>
---
 drivers/net/ethernet/airoha/airoha_eth.c | 21 +++++++++++++++------
 1 file changed, 15 insertions(+), 6 deletions(-)

diff --git a/drivers/net/ethernet/airoha/airoha_eth.c b/drivers/net/ethernet/airoha/airoha_eth.c
index eab6a98d62b9..aaf7d8c8ccd3 100644
--- a/drivers/net/ethernet/airoha/airoha_eth.c
+++ b/drivers/net/ethernet/airoha/airoha_eth.c
@@ -2493,14 +2493,23 @@ static int airoha_qdma_set_trtcm_param(struct airoha_qdma *qdma, int channel,
 		     FIELD_PREP(TRTCM_METER_GROUP_MASK, group) |
 		     FIELD_PREP(TRTCM_PARAM_INDEX_MASK, idx) |
 		     FIELD_PREP(TRTCM_PARAM_RATE_TYPE_MASK, mode);
+	int i;
 
-	airoha_qdma_wr(qdma, REG_TRTCM_DATA_LOW(addr), val);
-	airoha_qdma_wr(qdma, REG_TRTCM_CFG_PARAM(addr), config);
+	for (i = 0; i < 100; i++) {
+		u32 data;
 
-	return read_poll_timeout(airoha_qdma_rr, val,
-				 val & TRTCM_PARAM_RW_DONE_MASK,
-				 USEC_PER_MSEC, 10 * USEC_PER_MSEC, true,
-				 qdma, REG_TRTCM_CFG_PARAM(addr));
+		airoha_qdma_wr(qdma, REG_TRTCM_DATA_LOW(addr), val);
+		wmb();
+		airoha_qdma_wr(qdma, REG_TRTCM_CFG_PARAM(addr), config);
+		if (airoha_qdma_get_trtcm_param(qdma, channel, addr, param,
+						mode, &data, NULL))
+			continue;
+
+		if (data == val)
+			break;
+	}
+
+	return i == 100 ? -EBUSY : 0;
 }
 
 static int airoha_qdma_set_trtcm_config(struct airoha_qdma *qdma, int channel,

---
base-commit: 4aacf509e537a711fa71bca9f234e5eb6968850e
change-id: 20260605-airoha_qdma_set_trtcm_param-retry-fix-a9d2956b9b2f

Best regards,
-- 
Lorenzo Bianconi <lorenzo at kernel.org>