[PATCH 3/3] net/ionic: add vdev support for embedded applications

[Ferruh Yigit]

On 2/16/2024 5:07 PM, Andrew Boyer wrote:
> Add support for running DPDK applications directly on AMD Pensando
> embedded HW. The platform exposes the device BARs through UIO. The
> UIO code in the common/ionic library walks the sysfs filesystem
> to identify the relevant BARs and map them into process memory.
> 
> The SoCs are named 'Capri' and 'Elba'.
> 
> The vdev device interface code is located in ionic_dev_vdev.c.
> 
> Some datapath operations are #ifdef-ed out to save on resources when
> running in embedded mode.
> 
> Some controlpath operations are skipped by the ionic_is_embedded()
> helper function.
> 
> Before ringing the doorbell, use an ARM 'dsb st' barrier. The normal
> barrier inside rte_write64() is insufficient on these devices due to
> a chip errata.
> 
> Signed-off-by: Andrew Boyer <andrew.boyer at amd.com>
> Signed-off-by: Neel Patel <neel.patel at amd.com>
> Signed-off-by: R Mohamed Shah <mohamedshah.r at amd.com>
> Signed-off-by: Alfredo Cardigliano <cardigliano at ntop.org>

<...>

> +static struct rte_vdev_driver rte_vdev_ionic_pmd = {
> +	.probe = eth_ionic_vdev_probe,
> +	.remove = eth_ionic_vdev_remove,
> +};
> +
> +RTE_PMD_REGISTER_VDEV(net_ionic, rte_vdev_ionic_pmd);
> +
> +static void
> +vdev_ionic_scan_cb(__rte_unused void *arg)
> +{
> +	ionic_uio_scan_mnet_devices();
> +}
> +
> +RTE_INIT(vdev_ionic_custom_add)
> +{
> +	rte_vdev_add_custom_scan(vdev_ionic_scan_cb, NULL);
> +}

Hi Andrew,

My understanding is 'rte_vdev_add_custom_scan()' to add a vdev
automatically (via rte_devargs_add()) before vdev scan starts.

As far as I can see you are not doing this, why callback is added?
Why not call 'ionic_uio_scan_mnet_devices()' within the
'eth_ionic_vdev_probe()'?