linux-kernel - Re: [RFC PATCH net-next v2 3/3] net: ti: icssm-prueth: Adds support for ICSSM RSTP switch

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Message-ID: <44ed3d16-a8d2-49f3-a6b4-16d9a14d1cc6@ti.com>
Date: Mon, 6 Oct 2025 20:08:07 +0530
From: "Anwar, Md Danish" <a0501179@...com>
To: Parvathi Pudi <parvathi@...thit.com>, <andrew+netdev@...n.ch>,
        <davem@...emloft.net>, <edumazet@...gle.com>, <kuba@...nel.org>,
        <pabeni@...hat.com>, <danishanwar@...com>, <rogerq@...nel.org>,
        <pmohan@...thit.com>, <basharath@...thit.com>, <afd@...com>
CC: <linux-kernel@...r.kernel.org>, <netdev@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>, <pratheesh@...com>,
        <prajith@...com>, <vigneshr@...com>, <praneeth@...com>, <srk@...com>,
        <rogerq@...com>, <krishna@...thit.com>, <mohan@...thit.com>
Subject: Re: [RFC PATCH net-next v2 3/3] net: ti: icssm-prueth: Adds support
 for ICSSM RSTP switch

Hi Parvathi,

On 10/6/2025 4:17 PM, Parvathi Pudi wrote:
> From: Roger Quadros <rogerq@...com>
> 
> Adds support for RSTP switch mode by enhancing the existing ICSSM dual EMAC
> driver with switchdev support.
> 
> With this patch, the PRU-ICSSM is now capable of operating in switch mode
> with the 2 PRU ports acting as external ports and the host acting as an
> internal port. Packets received from the PRU ports will be forwarded to
> the host (store and forward mode) and also to the other PRU port (either
> using store and forward mode or via cut-through mode). Packets coming
> from the host will be transmitted either from one or both of the PRU ports
> (depending on the FDB decision).
> 
> By default, the dual EMAC firmware will be loaded in the PRU-ICSS
> subsystem. To configure the PRU-ICSS to operate as a switch, a different
> firmware must to be loaded.
> 
> Reviewed-by: Mohan Reddy Putluru <pmohan@...thit.com>
> Signed-off-by: Roger Quadros <rogerq@...com>
> Signed-off-by: Andrew F. Davis <afd@...com>
> Signed-off-by: Basharath Hussain Khaja <basharath@...thit.com>
> Signed-off-by: Parvathi Pudi <parvathi@...thit.com>
> ---

[ ... ]>
> +static void icssm_prueth_change_to_switch_mode(struct prueth *prueth)
> +{
> +	bool portstatus[PRUETH_NUM_MACS];
> +	struct prueth_emac *emac;
> +	struct net_device *ndev;
> +	int i, ret;
> +
> +	for (i = 0; i < PRUETH_NUM_MACS; i++) {
> +		emac = prueth->emac[i];
> +		ndev = emac->ndev;
> +
> +		portstatus[i] = netif_running(ndev);
> +		if (!portstatus[i])
> +			continue;
> +
> +		ret = ndev->netdev_ops->ndo_stop(ndev);
> +		if (ret < 0) {
> +			netdev_err(ndev, "failed to stop: %d", ret);
> +			return;
> +		}
> +	}
> +
> +	prueth->eth_type = PRUSS_ETHTYPE_SWITCH;
> +
> +	for (i = 0; i < PRUETH_NUM_MACS; i++) {
> +		emac = prueth->emac[i];
> +		ndev = emac->ndev;
> +
> +		if (!portstatus[i])
> +			continue;
> +
> +		ret = ndev->netdev_ops->ndo_open(ndev);
> +		if (ret < 0) {
> +			netdev_err(ndev, "failed to start: %d", ret);
> +			return;
> +		}
> +	}
> +
> +	dev_info(prueth->dev, "TI PRU ethernet now in Switch mode\n");
> +}
> +
> +static void icssm_prueth_change_to_emac_mode(struct prueth *prueth)
> +{
> +	bool portstatus[PRUETH_NUM_MACS];
> +	struct prueth_emac *emac;
> +	struct net_device *ndev;
> +	int i, ret;
> +
> +	for (i = 0; i < PRUETH_NUM_MACS; i++) {
> +		emac = prueth->emac[i];
> +		ndev = emac->ndev;
> +
> +		portstatus[i] = netif_running(ndev);
> +		if (!portstatus[i])
> +			continue;
> +
> +		ret = ndev->netdev_ops->ndo_stop(ndev);
> +		if (ret < 0) {
> +			netdev_err(ndev, "failed to stop: %d", ret);
> +			return;
> +		}
> +	}
> +
> +	prueth->eth_type = PRUSS_ETHTYPE_EMAC;
> +
> +	for (i = 0; i < PRUETH_NUM_MACS; i++) {
> +		emac = prueth->emac[i];
> +		ndev = emac->ndev;
> +
> +		if (!portstatus[i])
> +			continue;
> +
> +		ret = ndev->netdev_ops->ndo_open(ndev);
> +		if (ret < 0) {
> +			netdev_err(ndev, "failed to start: %d", ret);
> +			return;
> +		}
> +	}
> +
> +	dev_info(prueth->dev, "TI PRU ethernet now in Dual EMAC mode\n");
> +}


The APIs icssm_prueth_change_to_emac_mode and
icssm_prueth_change_to_switch_mode seems identical. Won't it be better
to have one function to change modes and which mode to go to passed as
function argument.

	icssm_prueth_change_mode(prueth,mode);

This will also work seemlessly if you add more modes in future. With
current approach you will need to add new APIs
icssm_prueth_change_to_xyz_mode()


-- 
Thanks and Regards,
Md Danish Anwar