linux-kernel - Re: [PATCH net-next v3 5/5] net: phy: add driver for built-in 2.5G ethernet PHY on MT7988

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Message-ID: <f65d90f7d044a507eed31feeecb907b9a5f8d05c.camel@mediatek.com>
Date: Fri, 24 May 2024 04:44:39 +0000
From: SkyLake Huang (黃啟澤)
	<SkyLake.Huang@...iatek.com>
To: "andrew@...n.ch" <andrew@...n.ch>
CC: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-mediatek@...ts.infradead.org" <linux-mediatek@...ts.infradead.org>,
	"linux@...linux.org.uk" <linux@...linux.org.uk>, "kuba@...nel.org"
	<kuba@...nel.org>, "pabeni@...hat.com" <pabeni@...hat.com>,
	"edumazet@...gle.com" <edumazet@...gle.com>,
	"linux-arm-kernel@...ts.infradead.org"
	<linux-arm-kernel@...ts.infradead.org>, "netdev@...r.kernel.org"
	<netdev@...r.kernel.org>, "dqfext@...il.com" <dqfext@...il.com>,
	"matthias.bgg@...il.com" <matthias.bgg@...il.com>,
	Steven Liu (劉人豪) <steven.liu@...iatek.com>,
	"davem@...emloft.net" <davem@...emloft.net>, "hkallweit1@...il.com"
	<hkallweit1@...il.com>, "angelogioacchino.delregno@...labora.com"
	<angelogioacchino.delregno@...labora.com>, "daniel@...rotopia.org"
	<daniel@...rotopia.org>
Subject: Re: [PATCH net-next v3 5/5] net: phy: add driver for built-in 2.5G
 ethernet PHY on MT7988

On Tue, 2024-05-21 at 19:28 +0200, Andrew Lunn wrote:
>  	 
> External email : Please do not click links or open attachments until
> you have verified the sender or the content.
>  On Tue, May 21, 2024 at 08:17:32AM +0000, SkyLake Huang (黃啟澤) wrote:
> > On Mon, 2024-05-20 at 15:35 +0200, Andrew Lunn wrote:
> > >   
> > > External email : Please do not click links or open attachments
> until
> > > you have verified the sender or the content.
> > >  > +static int mt798x_2p5ge_phy_config_init(struct phy_device
> > > *phydev)
> > > > +{
> > > > +struct mtk_i2p5ge_phy_priv *priv = phydev->priv;
> > > > +struct device *dev = &phydev->mdio.dev;
> > > > +const struct firmware *fw;
> > > > +struct pinctrl *pinctrl;
> > > > +int ret, i;
> > > > +u16 reg;
> > > > +
> > > > +if (!priv->fw_loaded) {
> > > > +if (!priv->md32_en_cfg_base || !priv->pmb_addr) {
> > > > +dev_err(dev, "MD32_EN_CFG base & PMB addresses aren't
> valid\n");
> > > > +return -EINVAL;
> > > > +}
> > > 
> > > ...
> > > 
> > > > +static int mt798x_2p5ge_phy_probe(struct phy_device *phydev)
> > > > +{
> > > > +struct mtk_i2p5ge_phy_priv *priv;
> > > > +
> > > > +priv = devm_kzalloc(&phydev->mdio.dev,
> > > > +    sizeof(struct mtk_i2p5ge_phy_priv), GFP_KERNEL);
> > > > +if (!priv)
> > > > +return -ENOMEM;
> > > > +
> > > > +switch (phydev->drv->phy_id) {
> > > > +case MTK_2P5GPHY_ID_MT7988:
> > > > +priv->pmb_addr = ioremap(MT7988_2P5GE_PMB_BASE,
> > > MT7988_2P5GE_PMB_LEN);
> > > > +if (!priv->pmb_addr)
> > > > +return -ENOMEM;
> > > > +priv->md32_en_cfg_base =
> ioremap(MT7988_2P5GE_MD32_EN_CFG_BASE,
> > > > + MT7988_2P5GE_MD32_EN_CFG_LEN);
> > > > +if (!priv->md32_en_cfg_base)
> > > > +return -ENOMEM;
> > > > +
> > > > +/* The original hardware only sets MDIO_DEVS_PMAPMD */
> > > > +phydev->c45_ids.mmds_present |= (MDIO_DEVS_PCS | MDIO_DEVS_AN
> |
> > > > + MDIO_DEVS_VEND1 | MDIO_DEVS_VEND2);
> > > > +break;
> > > > +default:
> > > > +return -EINVAL;
> > > > +}
> > > 
> > > How can priv->md32_en_cfg_base or priv->pmb_addr not be set in
> > > mt798x_2p5ge_phy_config_init()
> > > 
> > > Andrew
> > Use command "$ifconfig eth1 down" and then "$ifconfig eth1 up",
> > mt798x_2p5ge_phy_config_init() will be called again and again.
> priv-
> > >md32_en_cfg_base & priv->pmb_addr are released after first
> firmware
> > loading. So just check these two values again for safety once priv-
> > >fw_loaded is overrided unexpectedly.
> 
> So the code is unsymmetrical. The memory is mapped in
> mt798x_2p5ge_phy_probe() but unmapped in
> mt798x_2p5ge_phy_config_init(). It would be better style to unmap it
> in mt798x_2p5ge_phy_remove(). Alternatively, just map it when
> downloading firmware, and unmap it straight afterwards.
> 
> Also, we generally discourage defensive programming. It is much
> better
> to actually understand the code and know something is not possible.
> 
> Andrew

OK. I'll fix this in v5. Map & unmap it locally in
mt798x_2p5ge_phy_config_aneg()
 -> mt798x_2p5ge_hy_load_fw()

Sky