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 B7741351C04 for ; Thu, 26 Mar 2026 18:10:10 +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=1774548613; cv=none; b=s00nFdJ7Nx72fdaGISnGQm7/PVRntXhpGD39Xd1U+E9norq1UfKXxOpDYPFnaogD/8dF32u/DlFAp6//VEuVrnzQfDkVDfnug8LWWYZAimSlC0m98G60xvogmbdwQHxJ5MDqUMrrw0AwSlKpcFBGFqoCiZlO/O3oQl5aJ72hcd0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774548613; c=relaxed/simple; bh=C31T0iB05TcG8+dBb0BQwUARXXYeyW/ypNNov2Ya5G4=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=DQmwQH470k1FKt5aEEuXZrZm/4zj9v9hUte0lW1w7VilmEGFnt9kVQpEnptcPRZXgGNGE9jeibPtJQ1QQ3FMpYPaRJCOIn6zneaHuZk1xPzKqZUySUjpsKoX+eKVyBYozCK7fYg/wmJMI+XSbc8a6BJVXdMDeHkiRvwtLZvdKlM= 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=qgJYzpCR; 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="qgJYzpCR" 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=D7UKezHTYAPqledPGUEh2DO5MGs9hcwA+U9WoF1npkM=; b=qgJYzpCR7jCviujwEpZ0vv2vUF oxcFOACz5qSYZY/QQRwAwide7RZINgtbvEdKCebe7OUAUAo+e2poBx9eYb19KuV8uLhnUiVaLVELH QUAjK+E21l9asVws7NVaNBm75aKcthHu99WY9el+y++etD0SHfhZm3HN0+vQnPPTd8uB0LO9LZAUH giNrseuQbFoDjabUnZAiZNcYsep3qxXzKekLjeMLao49bqNPY7EDx65pAdw3u4Mv4SyHimrz4nbRa 4bT1eDcMFca1gLonlXQEhCKThWwxDzGzxX5U8ptEQWHvMqDQh2/lZW/6cLK8VAevQJhXaXWjVPXDX 7XvO9bhg==; Received: from shell.armlinux.org.uk ([fd8f:7570:feb6:1:5054:ff:fe00:4ec]:56258) 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 1w5p9h-0000000058m-3Fmw; Thu, 26 Mar 2026 18:10:05 +0000 Received: from linux by shell.armlinux.org.uk with local (Exim 4.98.2) (envelope-from ) id 1w5p9d-000000007Fh-3HE2; Thu, 26 Mar 2026 18:10:01 +0000 Date: Thu, 26 Mar 2026 18:10:01 +0000 From: "Russell King (Oracle)" To: Kieran Bingham Cc: Laurent Pinchart , imx@lists.linux.dev, netdev@vger.kernel.org, Andrew Lunn , "David S. Miller" , Eric Dumazet , Fabio Estevam , Francesco Dolcini , Frank Li , Jakub Kicinski , Joy Zou , Marco Felsch , Paolo Abeni , Pengutronix Kernel Team , Stefan Klug , linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH net-next v4 1/2] net: stmmac: provide flag to disable EEE Message-ID: References: <20260325210003.2752013-1-laurent.pinchart@ideasonboard.com> <20260325210003.2752013-2-laurent.pinchart@ideasonboard.com> <177454628933.1078312.13488207016388509694@ping.linuxembedded.co.uk> 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: <177454628933.1078312.13488207016388509694@ping.linuxembedded.co.uk> Sender: Russell King (Oracle) On Thu, Mar 26, 2026 at 05:31:29PM +0000, Kieran Bingham wrote: > This one has been a roller coaster, but I'm glad we got to the bottom of > it. > > I hope someone from synopsis takes note and and documents this for > future silicon integrations. I would say that it _is_ clearly documented in the databook. v3.74a 4.3.4. LPI Interrupt already states that this signal is generated in the receive clock domain, and is not cleared immediately after the LPI control and status register is read. It goes on to state that this is because the signal to clear it has to cross from the CSR clock domain to the receive clock domain to clear the signal - and states that it is at least _four_ receive clock cycles. So, if the dwmac core is operating at 10Mbps, that means its receive clock is running at 2.5MHz which has a period of 400ns. In this case, the four receive clock cycles to clear this interrupt is 1.6us, assuming that the receive clock is running. However, if EEE is enabled, the receive clock comes from the PHY, which may gate off when the link re-enters LPI - and this event is under the control of the remote end, not the local end. So, what this means is that even though it states four receive clocks to clear the lpi_intr_o signal, that doesn't necessarily mean it will clear in 1.6us as the receive clock may be stopped. So, I think it is clearly stated in the databook already, but as it's just two paragraphs buried in around 1500 pages, that may explain why it has been missed on iMX. -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTP is here! 80Mbps down 10Mbps up. Decent connectivity at last!