[PATCH v3 net] net: airoha: Fix TX scheduler queue mask loop upper bound

[PATCH v3 net] net: airoha: Fix TX scheduler queue mask loop upper bound

[Wayen Yan]

In airoha_qdma_set_chan_tx_sched(), the loop clearing queue mask was
using AIROHA_NUM_TX_RING (32) instead of AIROHA_NUM_QOS_QUEUES (8).

Each channel has 8 queues, and TXQ_DISABLE_CHAN_QUEUE_MASK(channel, i)
computes BIT(i + (channel * 8)). With i ranging 0..31, this causes:
- channel 0: clears bit 0..31 (all 4 channels) instead of 0..7
- channel 1: clears bit 8..31 (channels 1-3) instead of 8..15
- channel 2: clears bit 16..31 (channels 2-3) instead of 16..23
- channel 3: clears bit 24..31 (channel 3 only) - correct by accident

While BIT(32+) on arm64 produces 64-bit values truncated to 0 in u32
mask parameter, the loop still incorrectly clears queues within the
same channel beyond queue 7.

Even though this is functionally harmless (the register resets to 0
and is only ever cleared, never set — so clearing extra bits is a
no-op), the loop bound is semantically wrong and should be fixed for
correctness and clarity.

Fix by using AIROHA_NUM_QOS_QUEUES (8) as the loop upper bound.

Fixes: ef1ca9271313 ("net: airoha: Add sched HTB offload support")
Acked-by: Lorenzo Bianconi <lorenzo@kernel.org>
Signed-off-by: Wayen Yan <win847@gmail.com>
---
Changes in v3:
- Rebase on top of current net tree (Lorenzo pointed out v2 was
  not based on latest net HEAD).
- No code changes from v2.

 drivers/net/ethernet/airoha/airoha_eth.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/airoha/airoha_eth.c b/drivers/net/ethernet/airoha/airoha_eth.c
index 64dde6464f..47fb32517a 100644
--- a/drivers/net/ethernet/airoha/airoha_eth.c
+++ b/drivers/net/ethernet/airoha/airoha_eth.c
@@ -2395,7 +2395,7 @@ static int airoha_qdma_set_chan_tx_sched(struct net_device *netdev,
 	struct airoha_gdm_dev *dev = netdev_priv(netdev);
 	int i;
 
-	for (i = 0; i < AIROHA_NUM_TX_RING; i++)
+	for (i = 0; i < AIROHA_NUM_QOS_QUEUES; i++)
 		airoha_qdma_clear(dev->qdma, REG_QUEUE_CLOSE_CFG(channel),
 				  TXQ_DISABLE_CHAN_QUEUE_MASK(channel, i));
 
-- 
2.51.0