Re: [PATCH] net: phy: broadcom: add support for BCM5221 phy

["Russell King (Oracle)" <linux@armlinux.org.uk>]

On Fri, Aug 11, 2023 at 11:53:22PM +0200, Giulio Benetti wrote:
> +	reg = phy_read(phydev, MII_BRCM_FET_INTREG);
> +	if (reg < 0)
> +		return reg;
> +
> +	/* Unmask events we are interested in and mask interrupts globally. */
> +	reg = MII_BRCM_FET_IR_ENABLE |
> +	      MII_BRCM_FET_IR_MASK;
> +
> +	err = phy_write(phydev, MII_BRCM_FET_INTREG, reg);
> +	if (err < 0)
> +		return err;

Please explain why you read MII_BRCM_FET_INTREG, then discard its value
and write a replacement value.

> +
> +	/* Enable auto MDIX */
> +	err = phy_clear_bits(phydev, BCM5221_AEGSR, BCM5221_AEGSR_MDIX_DIS);
> +	if (err < 0)
> +		return err;
> +
> +	/* Enable shadow register access */
> +	brcmtest = phy_read(phydev, MII_BRCM_FET_BRCMTEST);
> +	if (brcmtest < 0)
> +		return brcmtest;
> +
> +	reg = brcmtest | MII_BRCM_FET_BT_SRE;
> +
> +	err = phy_write(phydev, MII_BRCM_FET_BRCMTEST, reg);
> +	if (err < 0)
> +		return err;

I think you should consider locking the MDIO bus while the device is
switched to the shadow register set, so that other accesses don't happen
that may interfere with this.

> +static int bcm5221_suspend(struct phy_device *phydev)
> +{
> +	int reg, err, err2, brcmtest;
> +
> +	/* Enable shadow register access */
> +	brcmtest = phy_read(phydev, MII_BRCM_FET_BRCMTEST);
> +	if (brcmtest < 0)
> +		return brcmtest;
> +
> +	reg = brcmtest | MII_BRCM_FET_BT_SRE;
> +
> +	err = phy_write(phydev, MII_BRCM_FET_BRCMTEST, reg);
> +	if (err < 0)
> +		return err;
> +
> +	/* Force Low Power Mode with clock enabled */
> +	err = phy_set_bits(phydev, MII_BRCM_FET_SHDW_AUXMODE4,
> +			   BCM5221_SHDW_AM4_EN_CLK_LPM |
> +			   BCM5221_SHDW_AM4_FORCE_LPM);
> +
> +	/* Disable shadow register access */
> +	err2 = phy_write(phydev, MII_BRCM_FET_BRCMTEST, brcmtest);
> +	if (!err)
> +		err = err2;

Same here.

> +
> +	return err;
> +}
> +
> +static int bcm5221_resume(struct phy_device *phydev)
> +{
> +	int reg, err, err2, brcmtest;
> +
> +	/* Enable shadow register access */
> +	brcmtest = phy_read(phydev, MII_BRCM_FET_BRCMTEST);
> +	if (brcmtest < 0)
> +		return brcmtest;
> +
> +	reg = brcmtest | MII_BRCM_FET_BT_SRE;
> +
> +	err = phy_write(phydev, MII_BRCM_FET_BRCMTEST, reg);
> +	if (err < 0)
> +		return err;
> +
> +	/* Exit Low Power Mode with clock enabled */
> +	err = phy_clear_bits(phydev, MII_BRCM_FET_SHDW_AUXMODE4,
> +			     BCM5221_SHDW_AM4_FORCE_LPM);
> +
> +	/* Disable shadow register access */
> +	err2 = phy_write(phydev, MII_BRCM_FET_BRCMTEST, brcmtest);
> +	if (!err)
> +		err = err2;

And, of course, same here.

Thanks.

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