From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 F05CC3115B8; Mon, 15 Dec 2025 14:03:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765807414; cv=none; b=C0Yc6DtXrq1OY13gdArrLXhD/LyOCrfPqzy+25E2YFPnd9keg760UxG2oLMAgeEg7vMjAajl9S5IC0fYq+FyByVf91lnIBfrOPTk4w67czR1ESHY8+zEkKUMmwX55O3mpgPyT5TQEq5vnXiP1HnGv9tUmGZSyT9u2XidDrgiio8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765807414; c=relaxed/simple; bh=rFQyuWHfFcZlHMejIvhAa1DF/jOp6uqvkdWv/+Mb6s0=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=kLNgK1O6EMlTyrlM5g1XZ91+ZiAcu8UAX9G5edktL1JvQso6/LMUhk6ycz9jUU7J5MY8X8EWgqS0G5/u8ppTZFKb4f/0+X2VdeojThwBNgsFpSZXsX931MD2IeBekcIl/uJ5qEJSo7eKx3p1/mMgIhQjULc8hgawcNJ6/z6ZyJY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Eqn+25td; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Eqn+25td" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 36D12C4CEF5; Mon, 15 Dec 2025 14:03:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1765807413; bh=rFQyuWHfFcZlHMejIvhAa1DF/jOp6uqvkdWv/+Mb6s0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Eqn+25tdHr5Wrrm3Xn8rbqWT7Cdod3hLETZm9Xr8ldxluc3aeOueqyGp5QHgBo4tp iudPuSduvdNkGWl9ZP4unZ071ajNA3y3RN1diT0GzQ7znJNaCUVfgYZ/jV/o2TkeRc H2gILEXItKx0IUuWaJk8gz1hQCIzU7AVCWete254A0km3zdQsa4prIUvq0ORAxN7vx xCHXokOZ0NAXxXlMvyrHR44hS2RFx5BNaATueokHHaVsn99rtLIqrTURa0g8jjIhCL YTUS3rgQzHofTHnfi7usX+RYStx+7nMXDKAWYeRn8cHAmDOoiJxHkhdH6349TudcnB 4xXdwcFnQQZpA== Date: Mon, 15 Dec 2025 08:03:30 -0600 From: Rob Herring To: Stefan Eichenberger Cc: andrew+netdev@lunn.ch, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, krzk+dt@kernel.org, conor+dt@kernel.org, hkallweit1@gmail.com, linux@armlinux.org.uk, geert+renesas@glider.be, ben.dooks@codethink.co.uk, netdev@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, francesco.dolcini@toradex.com, rafael.beims@toradex.com, Stefan Eichenberger Subject: Re: [PATCH net-next v1 2/3] dt-bindings: net: micrel: Add keep-preamble-before-sfd Message-ID: <20251215140330.GA2360845-robh@kernel.org> References: <20251212084657.29239-1-eichest@gmail.com> <20251212084657.29239-3-eichest@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@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: <20251212084657.29239-3-eichest@gmail.com> On Fri, Dec 12, 2025 at 09:46:17AM +0100, Stefan Eichenberger wrote: > From: Stefan Eichenberger > > Add a property to activate a Micrel PHY feature that keeps the preamble > enabled before the SFD (Start Frame Delimiter) is transmitted. > > This allows to workaround broken Ethernet controllers as found on the > NXP i.MX8MP. Specifically, errata ERR050694 that states: > ENET_QOS: MAC incorrectly discards the received packets when Preamble > Byte does not precede SFD or SMD. It doesn't really work right if you have to change the DT to work-around a quirk in the kernel. You should have all the information needed already in the DT. The compatible string for the i.MX8MP ethernet controller is not sufficient? > > The bit which disables this feature is not documented in the datasheet > from Micrel, but has been found by NXP and Micrel following this > discussion: > https://community.nxp.com/t5/i-MX-Processors/iMX8MP-eqos-not-working-for-10base-t/m-p/2151032 > > It has been tested on Verdin iMX8MP from Toradex by forcing the PHY to > 10MBit. Withouth this property set, no packets are received. With this > property set, reception works fine. What's the impact of just unconditionally setting this bit? Seems like any impact would be minimal given 10MBit is probably pretty rare now.