Re: [PATCH net-next v7 6/7] net: stmmac: support fp parameter of tc-taprio

Vladimir Oltean
2024-09-04T15:55:45Z

On Wed, Sep 04, 2024 at 05:21:21PM +0800, Furong Xu wrote:
> .../net/ethernet/stmicro/stmmac/stmmac_tc.c | 23 +++++++------------
> 1 file changed, 8 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_tc.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_tc.c
> index 9ec2e6ab81aa..2bdb22e175bc 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_tc.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_tc.c
> @@ -931,9 +931,9 @@ static int tc_taprio_configure(struct stmmac_priv *priv,
> struct tc_taprio_qopt_offload *qopt)
> {
> u32 size, wid = priv->dma_cap.estwid, dep = priv->dma_cap.estdep;
> + struct netlink_ext_ack *extack = qopt->mqprio.extack;
> struct timespec64 time, current_time, qopt_time;
> ktime_t current_time_ns;
> - bool fpe = false;
> int i, ret = 0;
> u64 ctr;
>
> @@ -1018,16 +1018,12 @@ static int tc_taprio_configure(struct stmmac_priv *priv,
>
> switch (qopt->entries[i].command) {
> case TC_TAPRIO_CMD_SET_GATES:
> - if (fpe)
> - return -EINVAL;
> break;
> case TC_TAPRIO_CMD_SET_AND_HOLD:
> gates |= BIT(0);
> - fpe = true;
> break;
> case TC_TAPRIO_CMD_SET_AND_RELEASE:
> gates &= ~BIT(0);
> - fpe = true;
> break;
> default:
> return -EOPNOTSUPP;
> @@ -1058,11 +1054,6 @@ static int tc_taprio_configure(struct stmmac_priv *priv,
>
> tc_taprio_map_maxsdu_txq(priv, qopt);
>
> - if (fpe && !priv->dma_cap.fpesel) {
> - mutex_unlock(&priv->est_lock);
> - return -EOPNOTSUPP;
> - }
> -
> ret = stmmac_est_configure(priv, priv, priv->est,
> priv->plat->clk_ptp_rate);
> mutex_unlock(&priv->est_lock);
> @@ -1071,6 +1062,11 @@ static int tc_taprio_configure(struct stmmac_priv *priv,
> goto disable;
> }
>
> + ret = stmmac_fpe_map_preemption_class(priv, priv->dev, extack,
> + qopt->mqprio.preemptible_tcs);
> + if (ret)
> + goto disable;
> +

Doesn't this break taprio for those callers of tc_setup_taprio() which
do not implement fpe_map_preemption_class(), but at least want taprio
without FPE nonetheless? As in the earlier mqprio patch, they will
return -EINVAL here.

Through code inspection, those users are:
- All users of .tc = dwxgmac_tc_ops: they have .mac = &dwxlgmac2_ops or
.mac = &dwxgmac210_ops, neither of which implements fpe_map_preemption_class().
- The users of .tc = &dwmac510_tc_ops which have .mac = &dwmac4_ops.
Again, this does not implement .fpe_map_preemption_class().

I can only rely on code inspection, because I don't know what is the
priv->dma_cap.estsel value that the above cores were synthesized with.
Thus, I don't know if we break a feature which was available before, or
one that was already unavailable.

My suggestion is similar: allow mqprio.preemptible_tcs to go to non-zero
only if fpe_map_preemption_class() is implemented. Then, program it with
any value (including 0) only if fpe_map_preemption_class() is implemented.

> netdev_info(priv->dev, "configured EST\n");
>
> return 0;