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

[Lorenzo Bianconi <lorenzo@kernel.org>]

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> 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.
> 
> Fix by using AIROHA_NUM_QOS_QUEUES (8) as the loop upper bound.
> 
> Fixes: ef1ca9271313 ("net: airoha: Add sched HTB offload support")
> Signed-off-by: Wayen Yan <win847@gmail.com>
> ---
>  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 31cdb11cd7..a1eda13400 100644
> --- a/drivers/net/ethernet/airoha/airoha_eth.c
> +++ b/drivers/net/ethernet/airoha/airoha_eth.c
> @@ -2217,7 +2217,7 @@ static int airoha_qdma_set_chan_tx_sched(struct net_device *dev,
>  	struct airoha_gdm_port *port = netdev_priv(dev);
>  	int i;
>  
> -	for (i = 0; i < AIROHA_NUM_TX_RING; i++)
> +	for (i = 0; i < AIROHA_NUM_QOS_QUEUES; i++)
>  		airoha_qdma_clear(port->qdma, REG_QUEUE_CLOSE_CFG(channel),
>  				  TXQ_DISABLE_CHAN_QUEUE_MASK(channel, i));

Even if the current codebase supports just AIROHA_NUM_QOS_CHANNEL (4), the hw
exposes 32 hw QoS channels (AIROHA_NUM_TX_RING). Here we are just clearing the
configuration, so I guess the current implementation is correct.

Regards,
Lorenzo

>  
> -- 
> 2.51.0
> 
> 

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