[PATCH net v2] 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>
---
Changes in v2:
- Wait for write configuration to be completed before running
  airoha_qdma_get_trtcm_param() in airoha_qdma_set_trtcm_param().
- Link to v1: https://lore.kernel.org/r/20260608-airoha_qdma_set_trtcm_param-retry-fix-v1-1-f07704f0d8c5@kernel.org
---
 drivers/net/ethernet/airoha/airoha_eth.c | 28 ++++++++++++++++++++++------
 1 file changed, 22 insertions(+), 6 deletions(-)

diff --git a/drivers/net/ethernet/airoha/airoha_eth.c b/drivers/net/ethernet/airoha/airoha_eth.c
index 3370c3df7c10..bb5c0599a4ee 100644
--- a/drivers/net/ethernet/airoha/airoha_eth.c
+++ b/drivers/net/ethernet/airoha/airoha_eth.c
@@ -2673,14 +2673,30 @@ 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 (read_poll_timeout(airoha_qdma_rr, data,
+				      data & TRTCM_PARAM_RW_DONE_MASK,
+				      USEC_PER_MSEC, 10 * USEC_PER_MSEC,
+				      true, qdma, REG_TRTCM_CFG_PARAM(addr)))
+			return -ETIMEDOUT;
+
+		if (airoha_qdma_get_trtcm_param(qdma, channel, addr, param,
+						mode, &data, NULL))
+			continue;
+
+		if (data == val)
+			return 0;
+	}
+
+	return -EBUSY;
 }
 
 static int airoha_qdma_set_trtcm_config(struct airoha_qdma *qdma, int channel,

---
base-commit: d07d80b6a129a44538cda1549b7acf95154fb197
change-id: 20260605-airoha_qdma_set_trtcm_param-retry-fix-a9d2956b9b2f

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