Re: [PATCH 14/16] NTB: ntb_transport: Enable direct-DMA queues

[Koichiro Den]

On Tue, Aug 11, 2026 at 01:51:33AM +0900, Koichiro Den wrote:
> Advertise direct RX when a DMA mapping device is available, and direct
> TX only when every QP has a suitable channel. Negotiation can then
> enable either direction independently.
> 
> Signed-off-by: Koichiro Den <den@xxxxxxxxxxxxx>
> ---
>  drivers/ntb/ntb_transport.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/ntb/ntb_transport.c b/drivers/ntb/ntb_transport.c
> index f2fa145994b9..9f5d6a407be7 100644
> --- a/drivers/ntb/ntb_transport.c
> +++ b/drivers/ntb/ntb_transport.c
> @@ -554,7 +554,7 @@ static bool ntb_direct_tx_mode(struct ntb_transport_qp *qp)
>  
>  static bool ntb_direct_link_capable(struct ntb_transport_qp *qp)
>  {
> -	return ntb_direct_rx_mode(qp) || ntb_direct_tx_mode(qp);
> +	return ntb_direct_layout(qp->transport);
>  }

Sorry, I got distracted while rearranging and polishing the series at the last
minute, leaving this meaningless intermediate diff here. :(

I'll properly fold it into the earlier commit in the next revision, so please
disregard this hunk for now. Sorry for the noise.

Best regards,
Koichiro

>  
>  static void ntb_transport_notify_peer(struct ntb_transport_qp *qp)
> @@ -2058,6 +2058,11 @@ static int ntb_transport_probe(struct ntb_client *self, struct ntb_dev *ndev)
>  	else if (use_direct_dma)
>  		dev_info(&ndev->dev,
>  			 "not enough scratchpads for direct DMA negotiation\n");
> +	if (nt->direct_dma_dev) {
> +		nt->direct_features = NTB_DIRECT_FEAT_RX;
> +		if (nt->qp_count && nt->qp_vec[0].direct_dma_chan)
> +			nt->direct_features |= NTB_DIRECT_FEAT_TX;
> +	}
>  
>  	mutex_init(&nt->link_event_lock);
>  	INIT_DELAYED_WORK(&nt->link_work, ntb_transport_link_work);
> -- 
> 2.51.0
>