netdev - Re: [PATCH net-next 07/10] net: mvneta: convert to phylink EEE implementation

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Message-ID: <20241213100415.GF2110@kernel.org>
Date: Fri, 13 Dec 2024 10:04:15 +0000
From: Simon Horman <horms@...nel.org>
To: "Russell King (Oracle)" <rmk+kernel@...linux.org.uk>
Cc: Andrew Lunn <andrew@...n.ch>, Heiner Kallweit <hkallweit1@...il.com>,
	Andrew Lunn <andrew+netdev@...n.ch>,
	Bryan Whitehead <bryan.whitehead@...rochip.com>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>,
	Marcin Wojtas <marcin.s.wojtas@...il.com>, netdev@...r.kernel.org,
	Paolo Abeni <pabeni@...hat.com>, UNGLinuxDriver@...rochip.com
Subject: Re: [PATCH net-next 07/10] net: mvneta: convert to phylink EEE
 implementation

On Mon, Dec 09, 2024 at 02:23:48PM +0000, Russell King (Oracle) wrote:
> Convert mvneta to use phylink's EEE implementation, which means we just
> need to implement the two methods for LPI control, and adding the
> initial configuration.
> 
> Disabling LPI requires clearing a single bit. Enabling LPI needs a full
> configuration of several values, as the timer values are dependent on
> the MAC operating speed.
> 
> As Armada 388 states that EEE is only supported in "SGMII" modes, mark
> this in lpi_interfaces. Testing with RGMII on the Clearfog platform
> indicates that the receive path fails to detect LPI over RGMII.
> 
> Signed-off-by: Russell King (Oracle) <rmk+kernel@...linux.org.uk>
> ---
>  drivers/net/ethernet/marvell/mvneta.c | 127 ++++++++++++++++----------
>  1 file changed, 79 insertions(+), 48 deletions(-)
> 
> diff --git a/drivers/net/ethernet/marvell/mvneta.c b/drivers/net/ethernet/marvell/mvneta.c

...

> +static void mvneta_mac_enable_tx_lpi(struct phylink_config *config, u32 timer,
> +				     bool tx_clk_stop)
> +{
> +	struct mvneta_port *pp = netdev_priv(to_net_dev(config->dev));
> +	u32 ts, tw, lpi0, lpi1, status;
> +
> +	status = mvreg_read(pp, MVNETA_GMAC_STATUS);
> +	if (status & MVNETA_GMAC_SPEED_1000) {
> +		/* At 1G speeds, the timer resolution are 1us, and
> +		 * 802.3 says tw is 16.5us. Round up to 17us.
> +		 */
> +		tw = 17;
> +		ts = timer;
> +	} else {
> +		/* At 100M speeds, the timer resolutions are 10us, and
> +		 * 802.3 says tw is 30us.
> +		 */
> +		tw = 3;
> +		ts = DIV_ROUND_UP(timer, 10);
>  	}
> +
> +	if (ts > 255)
> +		ts = 255;
> +
> +	/* Configure ts */
> +	lpi0 = mvreg_read(pp, MVNETA_LPI_CTRL_0);
> +	lpi0 = u32_replace_bits(lpi0, MVNETA_LPI_CTRL_0_TS, ts);

Hi Russell,

I think that the val and field arguments to u32_replace_bits() are
inverted here and this should be:

	lpi0 = u32_replace_bits(lpi0, ts, MVNETA_LPI_CTRL_0_TS);

> +	mvreg_write(pp, MVNETA_LPI_CTRL_0, lpi0);
> +
> +	/* Configure tw and enable LPI generation */
> +	lpi1 = mvreg_read(pp, MVNETA_LPI_CTRL_1);
> +	lpi1 = u32_replace_bits(lpi1, MVNETA_LPI_CTRL_1_TW, tw);

Ditto.

> +	lpi1 |= MVNETA_LPI_CTRL_1_REQUEST_ENABLE;
> +	mvreg_write(pp, MVNETA_LPI_CTRL_1, lpi1);
>  }
>  
>  static const struct phylink_mac_ops mvneta_phylink_ops = {

Flagged by clang-19 and gcc-14 W=1 builds.

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