[PATCH net v4] net: airoha: Add retry mechanism to airoha_qdma_set_trtcm_param()

[Christian Marangi]

From: Leto Liu (刘涛) <Leto.Liu 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: Leto Liu (刘涛) <Leto.Liu at airoha.com>
Signed-off-by: Christian Marangi <ansuelsmth at gmail.com>
---
Changes v4:
- Rebase on top of net
Changes v3:
- Init data
- Use continue instead of negative error for poll
- Add memory block after CFG_PARAM

 drivers/net/ethernet/airoha/airoha_eth.c | 29 +++++++++++++++++++-----
 1 file changed, 23 insertions(+), 6 deletions(-)

diff --git a/drivers/net/ethernet/airoha/airoha_eth.c b/drivers/net/ethernet/airoha/airoha_eth.c
index 79418e682f71..302f8c432055 100644
--- a/drivers/net/ethernet/airoha/airoha_eth.c
+++ b/drivers/net/ethernet/airoha/airoha_eth.c
@@ -2712,14 +2712,31 @@ 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 = 0;
 
-	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);
+		wmb();
+
+		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)))
+			continue;
+
+		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,
-- 
2.53.0