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

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Message-ID: <8f5ef5b1-ce52-1426-fe68-55c769885f9a@microchip.com>
Date:   Tue, 23 May 2023 06:15:38 +0000
From:   <Parthiban.Veerasooran@...rochip.com>
To:     <andrew@...n.ch>
CC:     <hkallweit1@...il.com>, <linux@...linux.org.uk>,
        <davem@...emloft.net>, <edumazet@...gle.com>, <kuba@...nel.org>,
        <pabeni@...hat.com>, <netdev@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>,
        <ramon.nordin.rodriguez@...roamp.se>,
        <Horatiu.Vultur@...rochip.com>, <Woojung.Huh@...rochip.com>,
        <Nicolas.Ferre@...rochip.com>, <Thorsten.Kummermehr@...rochip.com>
Subject: Re: [PATCH net-next v2 2/6] net: phy: microchip_t1s: replace
 read-modify-write code with phy_modify_mmd

Hi Andrew,

On 22/05/23 6:01 pm, Andrew Lunn wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
> 
>>
>>        /* 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.
Sure, I will add it in the next version.

Best Regards,
Parthiban V
> 
>> @@ -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
> 
> ---
> pw-bot: cr