Re: [PATCH net-next 6/6] net: dsa: sja1105: parse {rx,tx}-internal-delay-ps properties for RGMII delays

[Jakub Kicinski]

Some take it or leave it comments, checkpatch pointed out some extra
brackets so I had a look at the patch.

On Thu, 14 Oct 2021 01:23:13 +0300 Vladimir Oltean wrote:
> +	int rx_delay = -1, tx_delay = -1;
>  
> +	if (!phy_interface_mode_is_rgmii(phy_mode))
> +		return 0;
>  
> +	of_property_read_u32(port_dn, "rx-internal-delay-ps", &rx_delay);
> +	of_property_read_u32(port_dn, "tx-internal-delay-ps", &tx_delay);

If I'm reading this right you're depending on delays being left as -1
in case the property reads fail. Is this commonly accepted practice?
Why not code it up as:

	u32 rx_delay;

	if (of_property_read_u32(...))
		rx_delay = 0;
	else if (rx_delay != clamp(rx_delay, ...MIN, ...MAX)
		goto err;

or some such?

> +	if ((rx_delay && rx_delay < SJA1105_RGMII_DELAY_MIN_PS) ||
> +	    (tx_delay && tx_delay < SJA1105_RGMII_DELAY_MIN_PS) ||
> +	    (rx_delay > SJA1105_RGMII_DELAY_MAX_PS) ||
> +	    (tx_delay > SJA1105_RGMII_DELAY_MAX_PS)) {

nit: checkpatch says the brackets around the latter two are unnecessary,
     just in case it's not for symmetry / on purpose