From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 897EBEB64DC for ; Fri, 21 Jul 2023 16:20:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232525AbjGUQUG (ORCPT ); Fri, 21 Jul 2023 12:20:06 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45898 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232530AbjGUQTw (ORCPT ); Fri, 21 Jul 2023 12:19:52 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A2B804C31 for ; Fri, 21 Jul 2023 09:18:34 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 23EE161D14 for ; Fri, 21 Jul 2023 16:18:34 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3878DC433C7; Fri, 21 Jul 2023 16:18:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1689956313; bh=z5LZoxRrgbBp+zB7s0+ICMhj21qAjW9NCNmbW0BGw+4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=JBvtJlTCN6Cwc3adUlo2U0p6QOz6A3zeCBovJmkeTooa2g5SFTMW8u+skyCM2HEXy aQsLlgewwkpZbuNhpP4SO8KWFmlPqSUvObeOkD5ppS5Sr1Z4utx+rV7zKo1DIr/LMY H1vgAM+E3R2b+zo2iSZX2JW/0gCiPHoaq4dJ39sM= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Oleksij Rempel , Andrew Lunn , Jakub Kicinski Subject: [PATCH 6.4 135/292] net: phy: dp83td510: fix kernel stall during netboot in DP83TD510E PHY driver Date: Fri, 21 Jul 2023 18:04:04 +0200 Message-ID: <20230721160534.646700823@linuxfoundation.org> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20230721160528.800311148@linuxfoundation.org> References: <20230721160528.800311148@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Oleksij Rempel commit fc0649395dca81f2b3b02d9b248acb38cbcee55c upstream. Fix an issue where the kernel would stall during netboot, showing the "sched: RT throttling activated" message. This stall was triggered by the behavior of the mii_interrupt bit (Bit 7 - DP83TD510E_STS_MII_INT) in the DP83TD510E's PHY_STS Register (Address = 0x10). The DP83TD510E datasheet (2020) states that the bit clears on write, however, in practice, the bit clears on read. This discrepancy had significant implications on the driver's interrupt handling. The PHY_STS Register was used by handle_interrupt() to check for pending interrupts and by read_status() to get the current link status. The call to read_status() was unintentionally clearing the mii_interrupt status bit without deasserting the IRQ pin, causing handle_interrupt() to miss other pending interrupts. This issue was most apparent during netboot. The fix refrains from using the PHY_STS Register for interrupt handling. Instead, we now solely rely on the INTERRUPT_REG_1 Register (Address = 0x12) and INTERRUPT_REG_2 Register (Address = 0x13) for this purpose. These registers directly influence the IRQ pin state and are latched high until read. Note: The INTERRUPT_REG_2 Register (Address = 0x13) exists and can also be used for interrupt handling, specifically for "Aneg page received interrupt" and "Polarity change interrupt". However, these features are currently not supported by this driver. Fixes: 165cd04fe253 ("net: phy: dp83td510: Add support for the DP83TD510 Ethernet PHY") Cc: Signed-off-by: Oleksij Rempel Reviewed-by: Andrew Lunn Link: https://lore.kernel.org/r/20230621043848.3806124-1-o.rempel@pengutronix.de Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman --- drivers/net/phy/dp83td510.c | 23 +++++------------------ 1 file changed, 5 insertions(+), 18 deletions(-) --- a/drivers/net/phy/dp83td510.c +++ b/drivers/net/phy/dp83td510.c @@ -12,6 +12,11 @@ /* MDIO_MMD_VEND2 registers */ #define DP83TD510E_PHY_STS 0x10 +/* Bit 7 - mii_interrupt, active high. Clears on read. + * Note: Clearing does not necessarily deactivate IRQ pin if interrupts pending. + * This differs from the DP83TD510E datasheet (2020) which states this bit + * clears on write 0. + */ #define DP83TD510E_STS_MII_INT BIT(7) #define DP83TD510E_LINK_STATUS BIT(0) @@ -53,12 +58,6 @@ static int dp83td510_config_intr(struct int ret; if (phydev->interrupts == PHY_INTERRUPT_ENABLED) { - /* Clear any pending interrupts */ - ret = phy_write_mmd(phydev, MDIO_MMD_VEND2, DP83TD510E_PHY_STS, - 0x0); - if (ret) - return ret; - ret = phy_write_mmd(phydev, MDIO_MMD_VEND2, DP83TD510E_INTERRUPT_REG_1, DP83TD510E_INT1_LINK_EN); @@ -81,10 +80,6 @@ static int dp83td510_config_intr(struct DP83TD510E_GENCFG_INT_EN); if (ret) return ret; - - /* Clear any pending interrupts */ - ret = phy_write_mmd(phydev, MDIO_MMD_VEND2, DP83TD510E_PHY_STS, - 0x0); } return ret; @@ -94,14 +89,6 @@ static irqreturn_t dp83td510_handle_inte { int ret; - ret = phy_read_mmd(phydev, MDIO_MMD_VEND2, DP83TD510E_PHY_STS); - if (ret < 0) { - phy_error(phydev); - return IRQ_NONE; - } else if (!(ret & DP83TD510E_STS_MII_INT)) { - return IRQ_NONE; - } - /* Read the current enabled interrupts */ ret = phy_read_mmd(phydev, MDIO_MMD_VEND2, DP83TD510E_INTERRUPT_REG_1); if (ret < 0) {