From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from perceval.ideasonboard.com (perceval.ideasonboard.com [213.167.242.64]) (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 55BEF2F5A33 for ; Mon, 27 Oct 2025 10:02:45 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=213.167.242.64 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761559367; cv=none; b=S/l3PhluR3gt7FRU5GhBGKaH/Br5pLS3Be6+QeYwKer9RfgbhHOPR2ygoxjMSbLRCK6Cl/SqKoUACJmZmCC6HOAmIED9OjJ8Q1+cdThSGfC3VfTEznFFTIhiqZ2hDYvzbT5QoFoTRuCi0TqOzV16/EHQOgFKZob2YKyDd60+FZU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761559367; c=relaxed/simple; bh=oK4MAK69sWkbk17ePUCVJkTmSfCbcfChTa3yzciFfCU=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=GoyqnwZBhsiQYE7hKTNNy1pAy4VoH9ToJBeVapKBasLLmjyfvAfz2TpRh/FdYtupAa6Mwf2Bwqznh9H7j/1KtMtbKjFaoFHZKJSYT6vlvU8IVaMNhAQq44a514VUvik8jOTqcQ8LlnNzB3INryi775Kq06jl9AZucQTR801reX4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=ideasonboard.com; spf=pass smtp.mailfrom=ideasonboard.com; dkim=pass (1024-bit key) header.d=ideasonboard.com header.i=@ideasonboard.com header.b=gvZwhuMO; arc=none smtp.client-ip=213.167.242.64 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=ideasonboard.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=ideasonboard.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=ideasonboard.com header.i=@ideasonboard.com header.b="gvZwhuMO" Received: from pendragon.ideasonboard.com (unknown [193.209.96.36]) by perceval.ideasonboard.com (Postfix) with UTF8SMTPSA id 333831661; Mon, 27 Oct 2025 11:00:54 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1761559255; bh=oK4MAK69sWkbk17ePUCVJkTmSfCbcfChTa3yzciFfCU=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=gvZwhuMOZqzmB1g3j3ERKzn65qoVI2LnEaaIhmJCxS5l9MLEa7nDNA5PhOrw6B0xY 147oYuIZRQ/Fk4BWR0OplbvMWn5GQZFvuT175LT2qBY7sjl8FdEnHrhvzQ3rHdIIlX 1+Cn5HGek8rFHs0xxnZhLhwhJEJGNo963so3fo9o= Date: Mon, 27 Oct 2025 12:02:27 +0200 From: Laurent Pinchart To: Oleksij Rempel Cc: Andrew Lunn , Russell King , devicetree@vger.kernel.org, imx@lists.linux.dev, linux-arm-kernel@lists.infradead.org, Daniel Scally , Kieran Bingham , Stefan Klug , Conor Dooley , Fabio Estevam , Krzysztof Kozlowski , Pengutronix Kernel Team , Rob Herring , Sascha Hauer , Shawn Guo Subject: Re: [PATCH] arm64: dts: imx8mp-debix-model-a: Disable EEE for 1000T Message-ID: <20251027100227.GE1544@pendragon.ideasonboard.com> References: <20251026122905.29028-1-laurent.pinchart@ideasonboard.com> Precedence: bulk X-Mailing-List: imx@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: Hi Oleksij, On Mon, Oct 27, 2025 at 10:12:12AM +0100, Oleksij Rempel wrote: > On Mon, Oct 27, 2025 at 04:08:42AM +0100, Andrew Lunn wrote: > > Adding Russell King > > > > On Sun, Oct 26, 2025 at 02:29:04PM +0200, Laurent Pinchart wrote: > > > Energy Efficient Ethernet (EEE) is broken at least for 1000T on the EQOS > > > (DWMAC) interface. When connected to an EEE-enabled peer, the ethernet > > > devices produces an interrupts storm. Disable EEE support to fix it. > > > > > > Signed-off-by: Laurent Pinchart > > > --- > > > The exact reason for the interrupt storm is unknown, and my attempts to > > > diagnose it was hindered by my lack of expertise with DWMAC. As far as I > > > understand, the DWMAC implements EEE support, and so does the RTL8211E > > > PHY according to its datasheet. > > > > I believe for DWMAC it is a synthesis option. However, there is a bit > > indicating if the hardware supports it. > > > > The PHY should not be able to trigger an interrupt storm in the > > MAC. So this is likely to be an DWMAC issue. > > > > Which interrupt bit is causing the storm? > > > > > What each side does exactly is unknown > > > to me. One theory I've heard to explain the issue is that the two > > > implementations conflict. There is no register in the RTL8211E PHY to > > > disable EEE on the PHY side while still advertising its support to the > > > peer and relying on the implementation in the DWMAC (if this even makes > > > sense) > > > > It does not make sense. EEE is split into two major parts. The two > > PHYs communicate with each other to negotiate the feature, if both > > ends support it and both ends want to use it. The result of this > > negotiation is then passed to the MACs. > > > > It is then the MAC who decides when to send a Low Power Indication to > > the PHY to tell the PHY to enter low power mode. The MAC also wakes > > the PHY when it has packets to send. > > > > A quick look at the data sheet for the RTL8211E suggests this is what > > is supports. > > > > There are a few PHYs which implement SmartEEE, or some other similar > > name. They operate differently, the PHY does it all, and the MAC is > > not even aware EEE is happening. Such PHYs should really only be > > paired with MACs which do not support EEE. An EEE capable MAC paired > > with a SmartEEE PHY could have problems, but hopefully the EEE > > abilities and negotiation registers in the PHY would be sufficient to > > dissuade the MAC from doing EEE. But i would not expect a setup like > > this to trigger an interrupt storm. > > Please note, RTL8211E PHY do use undocumented SmartEEE mode by default. > It ignores RGMII LPI opcodes and doing own thing. It can be confirmed by > monitoring RGMII TX and MDI lines with oscilloscope and changing > tx-timer configurations. I also confirmed this information from other > source. To disable SmartEEE and use plain MAC based mode, NDA documentation > is needed. That's useful information, thank you. Would you by any chance to know if such NDA would allow contributing the feature upstream ? -- Regards, Laurent Pinchart