linux-kernel - Re: [PATCH v2 net-next 4/5] drivers/net/phy: add helpers to get/set PLCA configuration

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Date:   Mon, 9 Jan 2023 00:50:23 +0100
From:   Piergiorgio Beruto <piergiorgio.beruto@...il.com>
To:     Andrew Lunn <andrew@...n.ch>
Cc:     Heiner Kallweit <hkallweit1@...il.com>,
        Russell King <linux@...linux.org.uk>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>, linux-kernel@...r.kernel.org,
        netdev@...r.kernel.org, Oleksij Rempel <o.rempel@...gutronix.de>,
        mailhol.vincent@...adoo.fr, sudheer.mogilappagari@...el.com,
        sbhatta@...vell.com, linux-doc@...r.kernel.org,
        wangjie125@...wei.com, corbet@....net, lkp@...el.com,
        gal@...dia.com, gustavoars@...nel.org
Subject: Re: [PATCH v2 net-next 4/5] drivers/net/phy: add helpers to get/set
 PLCA configuration

On Sat, Jan 07, 2023 at 07:07:52PM +0100, Andrew Lunn wrote:
> > +/**
> > + * genphy_c45_plca_set_cfg - set PLCA configuration using standard registers
> > + * @phydev: target phy_device struct
> > + * @plca_cfg: structure containing the PLCA configuration. Fields set to -1 are
> > + * not to be changed.
> > + *
> > + * Description: if the PHY complies to the Open Alliance TC14 10BASE-T1S PLCA
> > + *   Management Registers specifications, this function can be used to modify
> > + *   the PLCA configuration using the standard registers in MMD 31.
> > + */
> > +int genphy_c45_plca_set_cfg(struct phy_device *phydev,
> > +			    const struct phy_plca_cfg *plca_cfg)
> > +{
> > +	int ret;
> > +	u16 val;
> > +
> > +	// PLCA IDVER is read-only
> > +	if (plca_cfg->version >= 0)
> > +		return -EINVAL;
> > +
> > +	// first of all, disable PLCA if required
> > +	if (plca_cfg->enabled == 0) {
> > +		ret = phy_clear_bits_mmd(phydev, MDIO_MMD_VEND2,
> > +					 MDIO_OATC14_PLCA_CTRL0,
> > +					 MDIO_OATC14_PLCA_EN);
> > +
> > +		if (ret < 0)
> > +			return ret;
> > +	}
> > +
> > +	if (plca_cfg->node_cnt >= 0 || plca_cfg->node_id >= 0) {
> > +		if (plca_cfg->node_cnt < 0 || plca_cfg->node_id < 0) {
> 
> I think it would be good to add some comments since this code is not
> immediately obvious to me. I had to think about it for a while.
Yes, I realize it is not very intuitive at furst glance :-)
I have added a comment explaining that we need to read back the register
to perform merge/pure of the configuration IFF we need to set one among
node ID / node count but not both.

> 
> > +	if (plca_cfg->burst_cnt >= 0 || plca_cfg->burst_tmr >= 0) {
> > +		if (plca_cfg->burst_cnt < 0 || plca_cfg->burst_tmr < 0) {
> > +			ret = phy_read_mmd(phydev, MDIO_MMD_VEND2,
> > +					   MDIO_OATC14_PLCA_BURST);
> > +
> 
> This follows the same patterns, so maybe comments here as well?
Yup, added the same comment.
> 
> With that, you can add my Reviewed-by.
Thanks!
> 
>      Andrew