netdev - Re: [PATCH net 2/3] net: dsa: mt7530: move lowering TRGMII driving to mt7530

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Message-ID: <87B17946-4602-4D27-8756-7481846EDE35@arinc9.com>
Date:   Tue, 04 Apr 2023 22:37:22 +0300
From:   Arınç ÜNAL <arinc.unal@...nc9.com>
To:     Landen Chao (趙皎宏) 
        <Landen.Chao@...iatek.com>,
        "olteanv@...il.com" <olteanv@...il.com>,
        "andrew@...n.ch" <andrew@...n.ch>,
        "arinc9.unal@...il.com" <arinc9.unal@...il.com>,
        "f.fainelli@...il.com" <f.fainelli@...il.com>,
        Sean Wang <Sean.Wang@...iatek.com>,
        "kuba@...nel.org" <kuba@...nel.org>,
        "edumazet@...gle.com" <edumazet@...gle.com>,
        "pabeni@...hat.com" <pabeni@...hat.com>,
        "dqfext@...il.com" <dqfext@...il.com>,
        "matthias.bgg@...il.com" <matthias.bgg@...il.com>,
        "davem@...emloft.net" <davem@...emloft.net>,
        "angelogioacchino.delregno@...labora.com" 
        <angelogioacchino.delregno@...labora.com>
CC:     "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "erkin.bozoglu@...ont.com" <erkin.bozoglu@...ont.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-mediatek@...ts.infradead.org" 
        <linux-mediatek@...ts.infradead.org>
Subject: Re: [PATCH net 2/3] net: dsa: mt7530: move lowering TRGMII driving to mt7530_setup()

On 26 March 2023 21:13:49 GMT+03:00, "Landen Chao (趙皎宏)" <Landen.Chao@...iatek.com> wrote:
>On Mon, 2023-03-20 at 22:05 +0300, arinc9.unal@...il.com wrote:
>> 
>> I asked this before, MT7530 DSA driver maintainers, please explain
>> the code
>> I mentioned on the second paragraph.
>> 
>> ---
>> @@ -2207,6 +2198,15 @@ mt7530_setup(struct dsa_switch *ds)
>> 
>>         mt7530_pll_setup(priv);
>> 
>> +       /* Lower Tx driving for TRGMII path */
>> +       for (i = 0; i < NUM_TRGMII_CTRL; i++)
>> +               mt7530_write(priv, MT7530_TRGMII_TD_ODT(i),
>> +                            TD_DM_DRVP(8) | TD_DM_DRVN(8));
>> +
>I guess you ask this part, and I try my best to recall what the
>original author said years ago.
>It is used to adjust the RX delay of port 6 to match the tx
>signal of the link partner.

Ok, thanks for replying. I will move this at the end, inside 'if (trgint)'. Since this doesn't lower the driving, there's no apparent benefit to run this if trgmii is not being used.

Arınç