[Linux-stm32] [PATCH net-next 1/1] net: stmmac: add per-queue TX & RX coalesce ethtool support

[Jakub Kicinski]

On Tue, 16 Mar 2021 04:44:17 +0000 Ong, Boon Leong wrote:
> >> +	if (queue < tx_cnt) {
> >> +		ec->tx_coalesce_usecs = priv->tx_coal_timer[queue];
> >> +		ec->tx_max_coalesced_frames = priv->tx_coal_frames[queue];
> >> +	} else {
> >> +		ec->tx_coalesce_usecs = -1;
> >> +		ec->tx_max_coalesced_frames = -1;
> >> +	}
> >> +
> >> +	if (priv->use_riwt && queue < rx_cnt) {
> >> +		ec->rx_max_coalesced_frames = priv->rx_coal_frames[queue];
> >> +		ec->rx_coalesce_usecs = stmmac_riwt2usec(priv-
> >>rx_riwt[queue],
> >> +							 priv);
> >> +	} else {
> >> +		ec->rx_max_coalesced_frames = -1;
> >> +		ec->rx_coalesce_usecs = -1;  
> >
> >Why the use of negative values? why not leave them as 0?  
> The initial logic was to return negative value to unsupported TXQ & RXQ
> since they are invalid. No preference here. So, we can leave it as all zeros.

I believe most drivers would leave it as 0, -1 seems unusual, have you
seen others doing this?