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Miller" , Emanuele Ghidoli , Eric Dumazet , Fabio Estevam , Heiner Kallweit , imx@lists.linux.dev, Jakub Kicinski , Kieran Bingham , linux-arm-kernel@lists.infradead.org, linux-stm32@st-md-mailman.stormreply.com, Maxime Coquelin , netdev@vger.kernel.org, Oleksij Rempel , Paolo Abeni , Pengutronix Kernel Team , Rob Herring , Sascha Hauer , Shawn Guo , Stefan Klug , Wei Fang , Laurent Pinchart References: Content-Language: en-US From: Ovidiu Panait In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260203_074212_906939_21BE1D4C X-CRM114-Status: GOOD ( 50.87 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi Russell, On 2/3/26 12:23 AM, Russell King (Oracle) wrote: > On Mon, Feb 02, 2026 at 08:54:52PM +0200, Ovidiu Panait wrote: >> >> Hi Russell, >> >> On 11/24/25 1:27 PM, Russell King (Oracle) wrote: >>> Some platforms have problems when EEE is enabled, and thus need a way >>> to disable stmmac EEE support. Add a flag before the other LPI related >>> flags which tells stmmac to avoid populating the phylink LPI >>> capabilities, which causes phylink to call phy_disable_eee() for any >>> PHY that is attached to the affected phylink instance. >>> >>> iMX8MP is an example - the lpi_intr_o signal is wired to an OR gate >>> along with the main dwmac interrupts. Since lpi_intr_o is synchronous >>> to the receive clock domain, and takes four clock cycles to clear, this >>> leads to interrupt storms as the interrupt remains asserted for some >>> time after the LPI control and status register is read. >>> >>> This problem becomes worse when the receive clock from the PHY stops >>> when the receive path enters LPI state - which means that lpi_intr_o >>> can not deassert until the clock restarts. Since the LPI state of the >>> receive path depends on the link partner, this is out of our control. >>> We could disable RX clock stop at the PHY, but that doesn't get around >>> the slow-to-deassert lpi_intr_o mentioned in the above paragraph. >>> >>> Previously, iMX8MP worked around this by disabling gigabit EEE, but >>> this is insufficient - the problem is also visible at 100M speeds, >>> where the receive clock is slower. >>> >>> There is extensive discussion and investigation in the thread linked >>> below, the result of which is summarised in this commit message. >>> >> >> We are seeing the same lpi_intr_o interrupt storm on the Renesas RZ/V2H >> EVK (dwmac-renesas-gbeth.c). On this platform, lpi_intr_o is routed as a >> separate, dedicated interrupt line to the CPU rather than being OR'd >> with the main DWMAC interrupt as on iMX8MP. This corresponds to the >> "eth_lpi" interrupt in the stmmac bindings: >> """ >> - description: The interrupt that occurs when Rx exits the LPI state >> const: eth_lpi >> """ >> >> Looking through the other glue drivers/device-trees, it looks to me that >> every platform that defines a separate "eth_lpi" irq might have the >> interrupt storm problem. > > That is highly likely. > >> To fix this issue on these platforms, rather than disabling EEE >> altogether, would it be possible to just not request the eth_lpi >> interrupt and let EEE continue to work? Perhaps a new flag could let >> each platform decide. > > Yes, because lpi_intr_o serves no purpose from a software point of > view - see the commit message below for the details. I do like > removing code from stmmac :) > >> If not, maybe this patch could be merged to add the flag that disables >> EEE and I will just send a patch to disable EEE on our platforms as well. > > We still need the flag to disable EEE for platforms where lpi_intr_o is > logically OR'd with the other interrupts, so there's no way to ignore > its persistent assertion. > > 8<=== > From: "Russell King (Oracle)" > Subject: [PATCH net-next] net: stmmac: remove support for lpi_intr_o > > The dwmac databook for v3.74a states that lpi_intr_o is a sideband > signal which should be used to ungate the application clock, and this > signal is synchronous to the receive clock. The receive clock can run > at 2.5, 25 or 125MHz depending on the media speed, and can stop under > the control of the link partner. This means that the time it takes to > clear is dependent on the negotiated media speed, and thus can be 8, > 40, or 400ns after reading the LPI control and status register. > > It has been observed with some aggressive link partners, this clock > can stop while lpi_intr_o is still asserted, meaning that the signal > remains asserted for an indefinite period that the local system has > no direct control over. > > The LPI interrupts will still be signalled through the main interrupt > path in any case, and this path is not dependent on the receive clock. > > This, since we do not gate the application clock, and the chances of > adding clock gating in the future are slim due to the clocks being > ill-defined, lpi_intr_o serves no useful purpose. Remove the code which > requests the interrupt, and all associated code. > > Signed-off-by: Russell King (Oracle) Thanks for fixing this. I did some testing on the Renesas RZ/V2H board with this patch and didn't see any issues: Tested-by: Ovidiu Panait Ovidiu > --- > drivers/net/ethernet/stmicro/stmmac/common.h | 1 - > .../net/ethernet/stmicro/stmmac/dwmac-intel.c | 4 --- > .../ethernet/stmicro/stmmac/dwmac-loongson.c | 7 ---- > drivers/net/ethernet/stmicro/stmmac/stmmac.h | 2 -- > .../net/ethernet/stmicro/stmmac/stmmac_main.c | 36 ------------------- > .../ethernet/stmicro/stmmac/stmmac_platform.c | 8 ----- > include/linux/stmmac.h | 1 - > 7 files changed, 59 deletions(-) > > diff --git a/drivers/net/ethernet/stmicro/stmmac/common.h b/drivers/net/ethernet/stmicro/stmmac/common.h > index 1c5a4af85b58..d26e8a063022 100644 > --- a/drivers/net/ethernet/stmicro/stmmac/common.h > +++ b/drivers/net/ethernet/stmicro/stmmac/common.h > @@ -394,7 +394,6 @@ enum request_irq_err { > REQ_IRQ_ERR_SFTY, > REQ_IRQ_ERR_SFTY_UE, > REQ_IRQ_ERR_SFTY_CE, > - REQ_IRQ_ERR_LPI, > REQ_IRQ_ERR_WOL, > REQ_IRQ_ERR_MAC, > REQ_IRQ_ERR_NO, > diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac-intel.c b/drivers/net/ethernet/stmicro/stmmac/dwmac-intel.c > index aad1be1ec4c1..92d77b0c2f54 100644 > --- a/drivers/net/ethernet/stmicro/stmmac/dwmac-intel.c > +++ b/drivers/net/ethernet/stmicro/stmmac/dwmac-intel.c > @@ -719,7 +719,6 @@ static int intel_mgbe_common_data(struct pci_dev *pdev, > > /* Setup MSI vector offset specific to Intel mGbE controller */ > plat->msi_mac_vec = 29; > - plat->msi_lpi_vec = 28; > plat->msi_sfty_ce_vec = 27; > plat->msi_sfty_ue_vec = 26; > plat->msi_rx_base_vec = 0; > @@ -1177,8 +1176,6 @@ static int stmmac_config_multi_msi(struct pci_dev *pdev, > res->irq = pci_irq_vector(pdev, plat->msi_mac_vec); > if (plat->msi_wol_vec < STMMAC_MSI_VEC_MAX) > res->wol_irq = pci_irq_vector(pdev, plat->msi_wol_vec); > - if (plat->msi_lpi_vec < STMMAC_MSI_VEC_MAX) > - res->lpi_irq = pci_irq_vector(pdev, plat->msi_lpi_vec); > if (plat->msi_sfty_ce_vec < STMMAC_MSI_VEC_MAX) > res->sfty_ce_irq = pci_irq_vector(pdev, plat->msi_sfty_ce_vec); > if (plat->msi_sfty_ue_vec < STMMAC_MSI_VEC_MAX) > @@ -1294,7 +1291,6 @@ static int intel_eth_pci_probe(struct pci_dev *pdev, > */ > plat->msi_mac_vec = STMMAC_MSI_VEC_MAX; > plat->msi_wol_vec = STMMAC_MSI_VEC_MAX; > - plat->msi_lpi_vec = STMMAC_MSI_VEC_MAX; > plat->msi_sfty_ce_vec = STMMAC_MSI_VEC_MAX; > plat->msi_sfty_ue_vec = STMMAC_MSI_VEC_MAX; > plat->msi_rx_base_vec = STMMAC_MSI_VEC_MAX; > diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac-loongson.c b/drivers/net/ethernet/stmicro/stmmac/dwmac-loongson.c > index ed0b534d8d7b..d66ae6ea4df5 100644 > --- a/drivers/net/ethernet/stmicro/stmmac/dwmac-loongson.c > +++ b/drivers/net/ethernet/stmicro/stmmac/dwmac-loongson.c > @@ -442,13 +442,6 @@ static int loongson_dwmac_dt_config(struct pci_dev *pdev, > res->wol_irq = res->irq; > } > > - res->lpi_irq = of_irq_get_byname(np, "eth_lpi"); > - if (res->lpi_irq < 0) { > - dev_err(&pdev->dev, "IRQ eth_lpi not found\n"); > - ret = -ENODEV; > - goto err_put_node; > - } > - > ret = device_get_phy_mode(&pdev->dev); > if (ret < 0) { > dev_err(&pdev->dev, "phy_mode not found\n"); > diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac.h b/drivers/net/ethernet/stmicro/stmmac/stmmac.h > index 012b0a477255..aafd8c39be63 100644 > --- a/drivers/net/ethernet/stmicro/stmmac/stmmac.h > +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac.h > @@ -31,7 +31,6 @@ struct stmmac_resources { > void __iomem *addr; > u8 mac[ETH_ALEN]; > int wol_irq; > - int lpi_irq; > int irq; > int sfty_irq; > int sfty_ce_irq; > @@ -297,7 +296,6 @@ struct stmmac_priv { > int wol_irq; > u32 gmii_address_bus_config; > struct timer_list eee_ctrl_timer; > - int lpi_irq; > u32 tx_lpi_timer; > bool tx_lpi_clk_stop; > bool eee_enabled; > diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c > index 7a451ae19f50..7925575fb348 100644 > --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c > +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c > @@ -3734,10 +3734,6 @@ static void stmmac_free_irq(struct net_device *dev, > free_irq(priv->sfty_ce_irq, dev); > fallthrough; > case REQ_IRQ_ERR_SFTY_CE: > - if (priv->lpi_irq > 0 && priv->lpi_irq != dev->irq) > - free_irq(priv->lpi_irq, dev); > - fallthrough; > - case REQ_IRQ_ERR_LPI: > if (priv->wol_irq > 0 && priv->wol_irq != dev->irq) > free_irq(priv->wol_irq, dev); > fallthrough; > @@ -3795,24 +3791,6 @@ static int stmmac_request_irq_multi_msi(struct net_device *dev) > } > } > > - /* Request the LPI IRQ in case of another line > - * is used for LPI > - */ > - if (priv->lpi_irq > 0 && priv->lpi_irq != dev->irq) { > - int_name = priv->int_name_lpi; > - sprintf(int_name, "%s:%s", dev->name, "lpi"); > - ret = request_irq(priv->lpi_irq, > - stmmac_mac_interrupt, > - 0, int_name, dev); > - if (unlikely(ret < 0)) { > - netdev_err(priv->dev, > - "%s: alloc lpi MSI %d (error: %d)\n", > - __func__, priv->lpi_irq, ret); > - irq_err = REQ_IRQ_ERR_LPI; > - goto irq_error; > - } > - } > - > /* Request the common Safety Feature Correctible/Uncorrectible > * Error line in case of another line is used > */ > @@ -3952,19 +3930,6 @@ static int stmmac_request_irq_single(struct net_device *dev) > } > } > > - /* Request the IRQ lines */ > - if (priv->lpi_irq > 0 && priv->lpi_irq != dev->irq) { > - ret = request_irq(priv->lpi_irq, stmmac_interrupt, > - IRQF_SHARED, dev->name, dev); > - if (unlikely(ret < 0)) { > - netdev_err(priv->dev, > - "%s: ERROR: allocating the LPI IRQ %d (%d)\n", > - __func__, priv->lpi_irq, ret); > - irq_err = REQ_IRQ_ERR_LPI; > - goto irq_error; > - } > - } > - > /* Request the common Safety Feature Correctible/Uncorrectible > * Error line in case of another line is used > */ > @@ -7752,7 +7717,6 @@ static int __stmmac_dvr_probe(struct device *device, > > priv->dev->irq = res->irq; > priv->wol_irq = res->wol_irq; > - priv->lpi_irq = res->lpi_irq; > priv->sfty_irq = res->sfty_irq; > priv->sfty_ce_irq = res->sfty_ce_irq; > priv->sfty_ue_irq = res->sfty_ue_irq; > diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c > index 8979a50b5507..5c9fd91a1db9 100644 > --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c > +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c > @@ -725,14 +725,6 @@ int stmmac_get_platform_resources(struct platform_device *pdev, > stmmac_res->wol_irq = stmmac_res->irq; > } > > - stmmac_res->lpi_irq = > - platform_get_irq_byname_optional(pdev, "eth_lpi"); > - if (stmmac_res->lpi_irq < 0) { > - if (stmmac_res->lpi_irq == -EPROBE_DEFER) > - return -EPROBE_DEFER; > - dev_info(&pdev->dev, "IRQ eth_lpi not found\n"); > - } > - > stmmac_res->sfty_irq = > platform_get_irq_byname_optional(pdev, "sfty"); > if (stmmac_res->sfty_irq < 0) { > diff --git a/include/linux/stmmac.h b/include/linux/stmmac.h > index 5199451dd0bc..2620f0217f88 100644 > --- a/include/linux/stmmac.h > +++ b/include/linux/stmmac.h > @@ -300,7 +300,6 @@ struct plat_stmmacenet_data { > int int_snapshot_num; > int msi_mac_vec; > int msi_wol_vec; > - int msi_lpi_vec; > int msi_sfty_ce_vec; > int msi_sfty_ue_vec; > int msi_rx_base_vec;