From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from pandora.armlinux.org.uk (pandora.armlinux.org.uk [78.32.30.218]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E61202F6918 for ; Mon, 23 Mar 2026 09:54:00 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=78.32.30.218 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774259642; cv=none; b=tO4g0cFEBWSebjtmK66z/T/fdZ8rQSl0Xrnjib4nOdziCnJtIw74bb5aoEQ7NU/98QHH2/O0QU+MaQQizv4pNBMCeCk4WKRAqfFOLimkPvkIwiD+Y4zRmejq4+cuS1a0YBMIJ9+2dDDXd3GlZkszbj/vLhmsfAO45gCJPtYXR0M= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774259642; c=relaxed/simple; bh=3HsKF4yCiA2gxjgM2E7yixnedzbJaMrRcQsR5RsO0j0=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Y9j66z4TgVaM/+0vIkIRqXE59KH5ZVvmLj62mE/Ct7prkEuBIQBZIDH5/vcRS0xUq+tMHRCYxoyXPYMy7prTVfauNvU8ScfXcQ0jZCLvqBSthlL2HyIrlzMDphk1l6JByhyIrmXs+87Kh1Ny0+Min1wxrRr0G83/1xehdFEChxk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=armlinux.org.uk; spf=none smtp.mailfrom=armlinux.org.uk; dkim=pass (2048-bit key) header.d=armlinux.org.uk header.i=@armlinux.org.uk header.b=Cxjo/Yn0; arc=none smtp.client-ip=78.32.30.218 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=armlinux.org.uk Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=armlinux.org.uk Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=armlinux.org.uk header.i=@armlinux.org.uk header.b="Cxjo/Yn0" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=armlinux.org.uk; s=pandora-2019; h=Sender:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=c1JtUgAJo9zz29RauK3FUJzPu0iLBjOxgL8d3JFQYgo=; b=Cxjo/Yn0PNrXJyYp78jYI1Lr3m ju8Kh2IvRY5ar5bE5Pw+4HTNk0GKuL4aEgKkhhVFh2kN/jnHBjSX4/N0WIIugMxhZnKVB4lInlcMG HtAA+hyqdOCA2kruIi0C35/bz3L//QZtb2JepV0Rai8uJZdTNMfgjdxXFh2Dg9IZw1sw91RnaP8Io fgQpwDXpxqpd/ThjJY80fbLgeHm29H4xXzRlziw37OvjpNrM1HCzCUap2NNVuTxrrNHILg8Fc1mnr DXWbtjrtjP1t+jNFZQAC38vH6rYaktnzIfwCcGtI77IgYt7JlonIIYcwy3LWm5V0BKnsFUrIpo3wL c3Z0XMKg==; Received: from shell.armlinux.org.uk ([fd8f:7570:feb6:1:5054:ff:fe00:4ec]:54524) by pandora.armlinux.org.uk with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.98.2) (envelope-from ) id 1w4byv-000000000Fk-2JZx; Mon, 23 Mar 2026 09:53:57 +0000 Received: from linux by shell.armlinux.org.uk with local (Exim 4.98.2) (envelope-from ) id 1w4byt-000000003w1-0vsp; Mon, 23 Mar 2026 09:53:55 +0000 Date: Mon, 23 Mar 2026 09:53:55 +0000 From: "Russell King (Oracle)" To: Laurent Pinchart Cc: netdev@vger.kernel.org, imx@lists.linux.dev, Andrew Lunn , "David S. Miller" , Eric Dumazet , Fabio Estevam , Francesco Dolcini , Frank Li , Jakub Kicinski , Joy Zou , Kieran Bingham , Marco Felsch , Paolo Abeni , Pengutronix Kernel Team , Stefan Klug , linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH v3 2/2] net: stmmac: imx: Disable EEE Message-ID: References: <20260323093933.1785583-1-laurent.pinchart@ideasonboard.com> <20260323093933.1785583-3-laurent.pinchart@ideasonboard.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260323093933.1785583-3-laurent.pinchart@ideasonboard.com> Sender: Russell King (Oracle) On Mon, Mar 23, 2026 at 11:39:33AM +0200, Laurent Pinchart wrote: > The i.MX8MP suffers from an interrupt storm related to the stmmac and > EEE. A long and tedious analysis ([1]) concluded that the SoC wires the > stmmac lpi_intr_o signal to an OR gate along with the main dwmac > interrupts, which causes an interrupt storm for two reasons. > > First, there's a race condition due to the interrupt deassertion being > synchronous to the RX clock domain: > > - When the PHY exits LPI mode, it restarts generating the RX clock > (clk_rx_i input signal to the GMAC). > - The MAC detects exit from LPI, and asserts lpi_intr_o. This triggers > the ENET_EQOS interrupt. > - Before the CPU has time to process the interrupt, the PHY enters LPI > mode again, and stops generating the RX clock. > - The CPU processes the interrupt and reads the GMAC4_LPI_CTRL_STATUS > registers. This does not clear lpi_intr_o as there's no clk_rx_i. > > An attempt was made to fixing the issue by not stopping RX_CLK in Rx LPI > state ([2]). This alleviates the symptoms but doesn't fix the issue. > Since lpi_intr_o takes four RX_CLK cycles to clear, an interrupt storm > can still occur during that window. In 1000T mode this is harder to > notice, but slower receive clocks cause hundreds to thousands of > spurious interrupts. > > Fix the issue by disabling EEE completely on i.MX8MP. > > [1] https://lore.kernel.org/all/20251026122905.29028-1-laurent.pinchart@ideasonboard.com/ > [2] https://lore.kernel.org/all/20251123053518.8478-1-laurent.pinchart@ideasonboard.com/ > > Signed-off-by: Laurent Pinchart Reviewed-by: Russell King (Oracle) Thanks! -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTP is here! 80Mbps down 10Mbps up. Decent connectivity at last!