Re: [PATCH v4 1/4] wifi: ath11k: use queue mapping for WCN6750 ring selection

[Tamizh Raja]

On Fri, Jul 24, 2026 at 11:01 AM Jose Ignacio Tornos Martinez
<jtornosm@xxxxxxxxxx> wrote:
>
> WCN6750 selects the TCL ring using skb_get_hash() to distribute
> flows across its 3 TX rings, as introduced in commit 7636c9a6e7d7
> ("wifi: ath11k: Add multi TX ring support for WCN6750"). The goal
> was to prevent out-of-order packet delivery that could occur with
> smp_processor_id()-based selection, where packets of the same flow
> could end up on different rings depending on CPU scheduling.
>
> Switch to skb_get_queue_mapping() instead, which returns the AC
> (access category) assigned by mac80211 in ieee80211_select_queue().
> This provides the same ordering guarantee: packets of the same TID
> always map to the same AC and therefore always land on the same
> ring, preventing reordering.
>
> Using queue mapping for ring selection also provides QoS-aware
> distribution, where each traffic class gets a deterministic ring
> assignment, rather than the random distribution that flow hashing
> produces. With 3 rings and 4 ACs (VO=0, VI=1, BE=2, BK=3), the
> mapping becomes: VO and BK share ring 0, VI uses ring 1, and BE
> uses ring 2.

Combining VO and BK is fine? since VO is a high priority. @baochen any
thought on this?
>
> This matches the approach already used by ath12k for WCN7850, which
> has the same ring count and uses skb_get_queue_mapping() for its
> ring selector.
>
> This change also removes the dependency on skb_get_hash(), which
> is relevant for a subsequent patch that removes the skb parameter
> from the get_ring_selector hw_ops callback entirely, enabling
> TX flow control in wake_tx_queue without requiring a complex peek
> to inspect frames before dequeue.
>
> Signed-off-by: Jose Ignacio Tornos Martinez <jtornosm@xxxxxxxxxx>
> ---
> v4: new patch
>
>  drivers/net/wireless/ath/ath11k/hw.c | 8 +-------
>  1 file changed, 1 insertion(+), 7 deletions(-)
>
> diff --git a/drivers/net/wireless/ath/ath11k/hw.c b/drivers/net/wireless/ath/ath11k/hw.c
> index 93f9a03c48dc..d679e39dce03 100644
> --- a/drivers/net/wireless/ath/ath11k/hw.c
> +++ b/drivers/net/wireless/ath/ath11k/hw.c
> @@ -891,13 +891,7 @@ static u32 ath11k_hw_ipq8074_get_tcl_ring_selector(struct sk_buff *skb)
>
>  static u32 ath11k_hw_wcn6750_get_tcl_ring_selector(struct sk_buff *skb)
>  {
> -       /* Select the TCL ring based on the flow hash of the SKB instead
> -        * of CPU ID. Since applications pumping the traffic can be scheduled
> -        * on multiple CPUs, there is a chance that packets of the same flow
> -        * could end on different TCL rings, this could sometimes results in
> -        * an out of order arrival of the packets at the receiver.
> -        */
> -       return skb_get_hash(skb);
> +       return skb_get_queue_mapping(skb);
>  }
>
>  const struct ath11k_hw_ops ipq8074_ops = {
> --
> 2.54.0
>
>


-- 
- Tamizh.