Re: [PATCH net-next 1/2] net: ti: icssg-prueth: Add Frame Preemption MAC Merge support

[Meghana Malladi]

Hi Simon,

On 1/15/26 20:27, Simon Horman wrote:
> On Wed, Jan 07, 2026 at 06:21:10PM +0530, Meghana Malladi wrote:
> > This patch adds utility functions to configure firmware to enable
> > IET FPE. The highest priority queue is marked as Express queue and
> > lower priority queues as pre-emptable, as the default configuration
> > which will be overwritten by the mqprio tc mask passed by tc qdisc.
> > Driver optionally allow configure the Verify state machine in the
> > firmware to check remote peer capability. If remote fails to respond
> > to Verify command, then FPE is disabled by firmware and TX FPE active
> > status is disabled.
> >
> > This also adds the necessary hooks to enable IET/FPE feature in ICSSG
> > driver. IET/FPE gets configured when Link is up and gets disabled when link
> > goes down or device is stopped.
> >
> > Signed-off-by: MD Danish Anwar <danishanwar@xxxxxx>
> > Signed-off-by: Meghana Malladi <m-malladi@xxxxxx>
>
> ...
>
> >   /* The buf includes headroom compatible with both skb and xdpf */
> > diff --git a/drivers/net/ethernet/ti/icssg/icssg_qos.c b/drivers/net/ethernet/ti/icssg/icssg_qos.c
>
> ...
>
> > +static int emac_tc_setup_mqprio(struct net_device *ndev, void *type_data)
> > +{
> > +	struct tc_mqprio_qopt_offload *mqprio = type_data;
> > +	struct prueth_emac *emac = netdev_priv(ndev);
> > +	struct prueth_qos_mqprio *p_mqprio;
> > +	int ret;
> > +
> > +	if (mqprio->qopt.hw == TC_MQPRIO_HW_OFFLOAD_TCS)
> > +		return -EOPNOTSUPP;
> > +
> > +	if (!mqprio->qopt.num_tc) {
> > +		netdev_reset_tc(ndev);
> > +		p_mqprio->preemptible_tcs = 0;
>
> Hi MD & Meghana,
>
> p_mqprio is dereferenced here.
> But it isn't initialised yet.
>
> Flagged by Clang 21.1.7 W=1 build for arm64.

Thanks for catching this.
Will include W=1 build test in my checklist before posting in upstream 
from next time :)

> > +		return 0;
> > +	}
> > +
> > +	ret = prueth_mqprio_validate(ndev, mqprio);
> > +	if (ret)
> > +		return ret;
> > +
> > +	p_mqprio = &emac->qos.mqprio;
> > +	memcpy(&p_mqprio->mqprio, mqprio, sizeof(*mqprio));
> > +	netdev_set_num_tc(ndev, mqprio->qopt.num_tc);
> > +
> > +	return 0;
> > +}
>
> ...