netdev - Re: net: sxgbe: using lpi

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Message-ID: <Z0cNfdxInR0XDQaV@pengutronix.de>
Date: Wed, 27 Nov 2024 13:15:57 +0100
From: Oleksij Rempel <o.rempel@...gutronix.de>
To: "Russell King (Oracle)" <linux@...linux.org.uk>
Cc: Andrew Lunn <andrew@...n.ch>, Heiner Kallweit <hkallweit1@...il.com>,
	Alexandre Torgue <alexandre.torgue@...s.st.com>,
	Andrew Lunn <andrew+netdev@...n.ch>,
	Bryan Whitehead <bryan.whitehead@...rochip.com>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Florian Fainelli <florian.fainelli@...adcom.com>,
	Jakub Kicinski <kuba@...nel.org>, Jose Abreu <joabreu@...opsys.com>,
	linux-arm-kernel@...ts.infradead.org,
	linux-stm32@...md-mailman.stormreply.com,
	Marcin Wojtas <marcin.s.wojtas@...il.com>,
	Maxime Coquelin <mcoquelin.stm32@...il.com>, netdev@...r.kernel.org,
	Paolo Abeni <pabeni@...hat.com>, UNGLinuxDriver@...rochip.com
Subject: Re: net: sxgbe: using lpi_timer for Twake timer

For archive:

static void  sxgbe_set_eee_timer(void __iomem *ioaddr,
				 const int ls, const int tw)
{
	int value = ((tw & 0xffff)) | ((ls & 0x7ff) << 16);

	/* Program the timers in the LPI timer control register:
	 * LS: minimum time (ms) for which the link
	 *  status from PHY should be ok before transmitting
	 *  the LPI pattern.
	 * TW: minimum time (us) for which the core waits
	 *  after it has stopped transmitting the LPI pattern.
	 */
	writel(value, ioaddr + SXGBE_CORE_LPI_TIMER_CTRL);
}

bool sxgbe_eee_init(struct sxgbe_priv_data * const priv)
{
....
	/* MAC core supports the EEE feature. */
	if (priv->hw_cap.eee) {
		/* Check if the PHY supports EEE */
		if (phy_init_eee(ndev->phydev, true))
			return false;

		timer_setup(&priv->eee_ctrl_timer, sxgbe_eee_ctrl_timer, 0);
		priv->eee_ctrl_timer.expires = SXGBE_LPI_TIMER(eee_timer);
		add_timer(&priv->eee_ctrl_timer);

		priv->hw->mac->set_eee_timer(priv->ioaddr,
					     SXGBE_DEFAULT_LPI_TIMER,
					     priv->tx_lpi_timer);
                                                   ^^^^^^^^^^^^
                                                   LPI timer is used for
						   Twake timer.
}

In case user configures lpi_timer value to too low, it will case frame
corruption instead of expected performance drop.

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