Re: [PATCH v2] enic: add ethtool get_channel support

From: Jakub Kicinski
Date: Tue Jun 25 2024 - 20:03:34 EST


On Mon, 24 Jun 2024 11:49:00 -0700 Jon Kohler wrote:
> + switch (vnic_dev_get_intr_mode(enic->vdev)) {
> + case VNIC_DEV_INTR_MODE_MSIX:
> + channels->max_rx = ENIC_RQ_MAX;
> + channels->max_tx = ENIC_WQ_MAX;
> + channels->rx_count = enic->rq_count;
> + channels->tx_count = enic->wq_count;
> + break;
> + case VNIC_DEV_INTR_MODE_MSI:
> + channels->max_rx = 1;
> + channels->max_tx = 1;
> + channels->rx_count = 1;
> + channels->tx_count = 1;
> + break;
> + case VNIC_DEV_INTR_MODE_INTX:
> + channels->max_combined = 1;
> + channels->combined_count = 1;
> + default:
> + break;
> + }

sorry for not responding properly to your earlier email, but I think
MSI should also be combined. What matters is whether the IRQ serves
just one of {Rx, Tx} or both.

For MSI, I see:

1 . enic_dev_init() does:
netif_napi_add(netdev, &enic->napi[0], enic_poll);
^^^^^^^^^

2. enic_request_intr() does
request_irq(enic->pdev->irq, enic_isr_msi, ...
^^^^^^^^^^^^

3. enic_isr_msi() does
napi_schedule_irqoff(&enic->napi[0]);
thus matching the NAPI from step #1.

4. enic_poll() calls both enic_wq_service, and enic_rq_service

So it's combined, AFAICT, similar to INTX in the relevant parts.
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