Re: [PATCH net-next v2 2/6] net: phy: microchip_t1s: replace read-modify-write code with phy_modify_mmd

From: Andrew Lunn
Date: Mon May 22 2023 - 08:38:07 EST


>
> /* Read-Modified Write Pseudocode (from AN1699)
> * current_val = read_register(mmd, addr) // Read current register value

Hi Parthiban

Maybe extend the comment to indicate that although AN1699 says Read,
Modify, Write, the write is not required if the register already has
the required value. That is what phy_modify_mmd() actually does.

> @@ -74,12 +72,11 @@ static int lan867x_config_init(struct phy_device *phydev)
> * write_register(mmd, addr, new_val) // Write back updated register value
> */
> for (int i = 0; i < ARRAY_SIZE(lan867x_fixup_registers); i++) {
> - reg = lan867x_fixup_registers[i];
> - reg_value = phy_read_mmd(phydev, MDIO_MMD_VEND2, reg);
> - reg_value &= ~lan867x_fixup_masks[i];
> - reg_value |= lan867x_fixup_values[i];
> - err = phy_write_mmd(phydev, MDIO_MMD_VEND2, reg, reg_value);
> - if (err != 0)
> + err = phy_modify_mmd(phydev, MDIO_MMD_VEND2,
> + lan867x_fixup_registers[i],
> + lan867x_fixup_masks[i],
> + lan867x_fixup_values[i]);
> + if (err)
> return err;
> }


Andrew

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