Re: [PATCH net-next v5 1/6] net: ti: icssg-prueth: Add functions to create and destroy Rx/Tx queues

[Simon Horman <horms@kernel.org>]

On Tue, Nov 11, 2025 at 03:45:18PM +0530, Meghana Malladi wrote:

...

> diff --git a/drivers/net/ethernet/ti/icssg/icssg_prueth.c b/drivers/net/ethernet/ti/icssg/icssg_prueth.c
> index 57a7d1ceab08..b66ffbfb499c 100644
> --- a/drivers/net/ethernet/ti/icssg/icssg_prueth.c
> +++ b/drivers/net/ethernet/ti/icssg/icssg_prueth.c
> @@ -735,6 +735,114 @@ static int icssg_update_vlan_mcast(struct net_device *vdev, int vid,
>  	return 0;
>  }
>  
> +static void prueth_destroy_txq(struct prueth_emac *emac)
> +{
> +	int ret, i;
> +
> +	atomic_set(&emac->tdown_cnt, emac->tx_ch_num);
> +	/* ensure new tdown_cnt value is visible */
> +	smp_mb__after_atomic();
> +	/* tear down and disable UDMA channels */
> +	reinit_completion(&emac->tdown_complete);
> +	for (i = 0; i < emac->tx_ch_num; i++)
> +		k3_udma_glue_tdown_tx_chn(emac->tx_chns[i].tx_chn, false);
> +
> +	ret = wait_for_completion_timeout(&emac->tdown_complete,
> +					  msecs_to_jiffies(1000));
> +	if (!ret)
> +		netdev_err(emac->ndev, "tx teardown timeout\n");
> +
> +	for (i = 0; i < emac->tx_ch_num; i++) {
> +		napi_disable(&emac->tx_chns[i].napi_tx);
> +		hrtimer_cancel(&emac->tx_chns[i].tx_hrtimer);
> +		k3_udma_glue_reset_tx_chn(emac->tx_chns[i].tx_chn,
> +					  &emac->tx_chns[i],
> +					  prueth_tx_cleanup);
> +		k3_udma_glue_disable_tx_chn(emac->tx_chns[i].tx_chn);
> +	}
> +}
> +
> +static void prueth_destroy_rxq(struct prueth_emac *emac)
> +{
> +	int i, ret;
> +
> +	/* tear down and disable UDMA channels */
> +	reinit_completion(&emac->tdown_complete);
> +	k3_udma_glue_tdown_rx_chn(emac->rx_chns.rx_chn, true);
> +
> +	/* When RX DMA Channel Teardown is initiated, it will result in an
> +	 * interrupt and a Teardown Completion Marker (TDCM) is queued into
> +	 * the RX Completion queue. Acknowledging the interrupt involves
> +	 * popping the TDCM descriptor from the RX Completion queue via the
> +	 * RX NAPI Handler. To avoid timing out when waiting for the TDCM to
> +	 * be popped, schedule the RX NAPI handler to run immediately.
> +	 */
> +	if (!napi_if_scheduled_mark_missed(&emac->napi_rx)) {
> +		if (napi_schedule_prep(&emac->napi_rx))
> +			__napi_schedule(&emac->napi_rx);
> +	}
> +
> +	ret = wait_for_completion_timeout(&emac->tdown_complete,
> +					  msecs_to_jiffies(1000));
> +	if (!ret)
> +		netdev_err(emac->ndev, "rx teardown timeout\n");
> +
> +	for (i = 0; i < PRUETH_MAX_RX_FLOWS; i++) {
> +		napi_disable(&emac->napi_rx);
> +		hrtimer_cancel(&emac->rx_hrtimer);

Hi Meghana,

Is it intentional that the napi_disable() and hrtimer_cancel()
are made once for each (possible) flow, rather than just once
as was the case before this patch?

Maybe the tx code, which does the same, was used as a template here
in error?

Flagged by Claude Code with https://github.com/masoncl/review-prompts/

> +		k3_udma_glue_reset_rx_chn(emac->rx_chns.rx_chn, i,
> +					  &emac->rx_chns,
> +					  prueth_rx_cleanup);
> +	}
> +
> +	prueth_destroy_xdp_rxqs(emac);
> +	k3_udma_glue_disable_rx_chn(emac->rx_chns.rx_chn);
> +}

...

> @@ -905,32 +988,8 @@ static int emac_ndo_stop(struct net_device *ndev)
>  	else
>  		__dev_mc_unsync(ndev, icssg_prueth_del_mcast);
>  
> -	atomic_set(&emac->tdown_cnt, emac->tx_ch_num);
> -	/* ensure new tdown_cnt value is visible */
> -	smp_mb__after_atomic();
> -	/* tear down and disable UDMA channels */
> -	reinit_completion(&emac->tdown_complete);
> -	for (i = 0; i < emac->tx_ch_num; i++)
> -		k3_udma_glue_tdown_tx_chn(emac->tx_chns[i].tx_chn, false);
> -
> -	ret = wait_for_completion_timeout(&emac->tdown_complete,
> -					  msecs_to_jiffies(1000));
> -	if (!ret)
> -		netdev_err(ndev, "tx teardown timeout\n");
> -
> -	prueth_reset_tx_chan(emac, emac->tx_ch_num, true);
> -	for (i = 0; i < emac->tx_ch_num; i++) {
> -		napi_disable(&emac->tx_chns[i].napi_tx);
> -		hrtimer_cancel(&emac->tx_chns[i].tx_hrtimer);
> -	}
> -
> -	max_rx_flows = PRUETH_MAX_RX_FLOWS;
> -	k3_udma_glue_tdown_rx_chn(emac->rx_chns.rx_chn, true);
> -
> -	prueth_reset_rx_chan(&emac->rx_chns, max_rx_flows, true);
> -	prueth_destroy_xdp_rxqs(emac);
> -	napi_disable(&emac->napi_rx);
> -	hrtimer_cancel(&emac->rx_hrtimer);
> +	prueth_destroy_txq(emac);
> +	prueth_destroy_rxq(emac);
>  
>  	cancel_work_sync(&emac->rx_mode_work);
>  
> @@ -943,10 +1002,10 @@ static int emac_ndo_stop(struct net_device *ndev)
>  
>  	free_irq(emac->tx_ts_irq, emac);
>  
> -	free_irq(emac->rx_chns.irq[rx_flow], emac);
> +	free_irq(emac->rx_chns.irq[PRUETH_RX_FLOW_DATA], emac);
>  	prueth_ndev_del_tx_napi(emac, emac->tx_ch_num);
>  
> -	prueth_cleanup_rx_chns(emac, &emac->rx_chns, max_rx_flows);
> +	prueth_cleanup_rx_chns(emac, &emac->rx_chns, PRUETH_MAX_RX_FLOWS);
>  	prueth_cleanup_tx_chns(emac);
>  
>  	prueth->emacs_initialized--;

...