linux-kernel - Re: [PATCH net-next 16/30] net: dsa: mt7530: move lowering port 5 RGMII driving to mt7530

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Message-ID: <20230526131739.5mso5y2d3ieelasf@skbuf>
Date:   Fri, 26 May 2023 16:17:39 +0300
From:   Vladimir Oltean <olteanv@...il.com>
To:     arinc9.unal@...il.com
Cc:     Sean Wang <sean.wang@...iatek.com>,
        Landen Chao <Landen.Chao@...iatek.com>,
        DENG Qingfang <dqfext@...il.com>,
        Daniel Golle <daniel@...rotopia.org>,
        Andrew Lunn <andrew@...n.ch>,
        Florian Fainelli <f.fainelli@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>,
        Russell King <linux@...linux.org.uk>,
        Arınç ÜNAL <arinc.unal@...nc9.com>,
        Richard van Schagen <richard@...terhints.com>,
        Richard van Schagen <vschagen@...com>,
        Frank Wunderlich <frank-w@...lic-files.de>,
        Bartel Eerdekens <bartel.eerdekens@...stell8.be>,
        erkin.bozoglu@...ont.com, mithat.guner@...ont.com,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org
Subject: Re: [PATCH net-next 16/30] net: dsa: mt7530: move lowering port 5
 RGMII driving to mt7530_setup()

On Mon, May 22, 2023 at 03:15:18PM +0300, arinc9.unal@...il.com wrote:
> From: Arınç ÜNAL <arinc.unal@...nc9.com>
> 
> Move lowering Tx driving of rgmii on port 5 to right before lowering of Tx
> driving of trgmii on port 6 on mt7530_setup().
> 
> This way, the switch should consume less power regardless of port 5 being
> used.
> 
> Tested-by: Arınç ÜNAL <arinc.unal@...nc9.com>
> Signed-off-by: Arınç ÜNAL <arinc.unal@...nc9.com>
> ---

This patch assumes that the MAC has its TXC ticking even when PMCR_TX_EN
is unset. Why would it do that?

>  drivers/net/dsa/mt7530.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/net/dsa/mt7530.c b/drivers/net/dsa/mt7530.c
> index f2c1aa9cf7f7..514e82299537 100644
> --- a/drivers/net/dsa/mt7530.c
> +++ b/drivers/net/dsa/mt7530.c
> @@ -933,10 +933,6 @@ static void mt7530_setup_port5(struct dsa_switch *ds, phy_interface_t interface)
>  		/* P5 RGMII TX Clock Control: delay x */
>  		mt7530_write(priv, MT7530_P5RGMIITXCR,
>  			     CSR_RGMII_TXC_CFG(0x10 + tx_delay));
> -
> -		/* reduce P5 RGMII Tx driving, 8mA */
> -		mt7530_write(priv, MT7530_IO_DRV_CR,
> -			     P5_IO_CLK_DRV(1) | P5_IO_DATA_DRV(1));
>  	}
>  
>  	mt7530_write(priv, MT7530_MHWTRAP, val);
> @@ -2209,6 +2205,10 @@ mt7530_setup(struct dsa_switch *ds)
>  
>  	mt7530_pll_setup(priv);
>  
> +	/* Lower P5 RGMII Tx driving, 8mA */
> +	mt7530_write(priv, MT7530_IO_DRV_CR,
> +			P5_IO_CLK_DRV(1) | P5_IO_DATA_DRV(1));

If you move code then preserve its alignment to the open parenthesis.

> +
>  	/* Lower Tx driving for TRGMII path */
>  	for (i = 0; i < NUM_TRGMII_CTRL; i++)
>  		mt7530_write(priv, MT7530_TRGMII_TD_ODT(i),
> -- 
> 2.39.2
>