From ef43e5132895ad59b45e38855d32e966bb7434d9 Mon Sep 17 00:00:00 2001 From: "Russell King (Oracle)" Date: Thu, 20 Mar 2025 22:11:12 +0000 Subject: [PATCH] net: stmmac: address non-LPI resume failures properly The Synopsys Designware GMAC core databook requires all clocks to be active in order to complete software reset, which we perform during resume. However, IEEE 802.3 allows a PHY to stop its clocks when placed in low-power mode, which happens when the system is suspended and WoL is not enabled. As an attempt to work around this, commit 36d18b5664ef ("net: stmmac: start phylink instance before stmmac_hw_setup()") started phylink early, but this has the side effect that the mac_link_up() method may be called before or during the initialisation of GMAC hardware. We also have the socfpga glue driver directly calling phy_resume() also as an attempt to work around this. In a previous commit, phylink_prepare_resume() has been introduced to give MAC drivers a way to ensure that the PHY is resumed prior to their initialisation of their MAC hardware. This commit adds the call, and moves the phylink_resume() call back to where it should be before the aforementioned commit. Signed-off-by: Russell King (Oracle) Link: https://patch.msgid.link/E1tvO6a-008Vjh-FG@rmk-PC.armlinux.org.uk Signed-off-by: Jakub Kicinski --- .../net/ethernet/stmicro/stmmac/stmmac_main.c | 19 ++++++++++++++----- 1 file changed, 14 insertions(+), 5 deletions(-) diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c index a6a533d8a45be..860f800cd014c 100644 --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c @@ -7936,12 +7936,12 @@ int stmmac_resume(struct device *dev) } rtnl_lock(); - phylink_resume(priv->phylink); - if (device_may_wakeup(priv->device) && !priv->plat->pmt) - phylink_speed_up(priv->phylink); - rtnl_unlock(); - rtnl_lock(); + /* Prepare the PHY to resume, ensuring that its clocks which are + * necessary for the MAC DMA reset to complete are running + */ + phylink_prepare_resume(priv->phylink); + mutex_lock(&priv->lock); stmmac_reset_queues_param(priv); @@ -7959,6 +7959,15 @@ int stmmac_resume(struct device *dev) stmmac_enable_all_dma_irq(priv); mutex_unlock(&priv->lock); + + /* phylink_resume() must be called after the hardware has been + * initialised because it may bring the link up immediately in a + * workqueue thread, which will race with initialisation. + */ + phylink_resume(priv->phylink); + if (device_may_wakeup(priv->device) && !priv->plat->pmt) + phylink_speed_up(priv->phylink); + rtnl_unlock(); netif_device_attach(ndev); -- 2.39.5