From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp16.bhosted.nl (smtp16.bhosted.nl [94.124.121.27]) (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 48D03311C16 for ; Thu, 18 Sep 2025 15:35:00 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=94.124.121.27 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758209702; cv=none; b=owJN3Nlxp9mHjmvzSEfV63GdYdOc+be30hHlISt3uxpWdIWjzq1B+TJDstPRCKdvnWFSQGtY6MijEha3Uuze20QXpXVhgg350yWE8liLS2pn7exHJ6T12WBLLdzrK0JEd/17PpWk0VreMwpQ7o8Vb0TIk2byhnWcVcxcVnA51iE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758209702; c=relaxed/simple; bh=1L4ztzZI21TGZatF3aNWfrnQCTgXQdveVEOhyL3fA0g=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=VP/cSWUM3PQCKXLyYBrFDFfHaYkC9ZuAlUYTSN/v+kKeAiFbmrIZUB3PgszslLEMADyf3PQ7diI6uJeFAa2cP3/eSHrZEAUmkcsn1lGlDo5BdymYSGoh1RRMBhiEKjTzSdI8x1BVvWqa25uCvZ4ENlmE86IwC1Sw9CaH/JTUFHw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=protonic.nl; spf=pass smtp.mailfrom=protonic.nl; dkim=pass (2048-bit key) header.d=protonic.nl header.i=@protonic.nl header.b=QQemO7m4; arc=none smtp.client-ip=94.124.121.27 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=protonic.nl Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=protonic.nl Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=protonic.nl header.i=@protonic.nl header.b="QQemO7m4" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=protonic.nl; s=202111; h=content-transfer-encoding:content-type:mime-version:references:in-reply-to: message-id:subject:cc:to:from:date:from; bh=SqjdATjfjZTk7QANAggTs1mW/P13EV6a+Izt0r+agQ0=; b=QQemO7m4x6zCxk4M9laZ90eCIBZvlHRq/VuixCptBB7zzwo7W14mF7GpiYLDE2KravDs5mWr5Fe32 YI5vbPnjY8XchNI9DA2VxwqrhGOoXIMDArJfiLqW1D+YRL2YnyHQ4WHp2jj+Z3dwdLVow44GMCxb0b S6ozX0oObc8Pf1HBbvovaxNrs8/iL/hnZAJYohUXXEqDuxD0E+wq2MS2PgcGQeAqkHwHgbtE3szPdO LY51aW6TvUu1QOAIlIzGxXruryI8IjrqSj/QbUYXHmCSZMbUySBHPD6UI6terkJcLsOTJupcY0AuoB JpIpBWXwmgF0fXl9CqpcwJtEM9ZcoKQ== X-MSG-ID: df093cf2-94a4-11f0-858c-005056817704 Date: Thu, 18 Sep 2025 17:33:47 +0200 From: David Jander To: Andrew Lunn Cc: Jonas Rebmann , Vladimir Oltean , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Liam Girdwood , Mark Brown , Shengjiu Wang , Shawn Guo , Sascha Hauer , Fabio Estevam , Pengutronix Kernel Team , Vladimir Oltean , netdev@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-sound@vger.kernel.org, imx@lists.linux.dev, linux-arm-kernel@lists.infradead.org, Lucas Stach , Oleksij Rempel Subject: Re: [PATCH v2 3/3] arm64: dts: add Protonic PRT8ML board Message-ID: <20250918173347.28db5569@erd003.prtnl> In-Reply-To: <7f1d9289-4102-4db9-a2bb-ff270e8871b7@lunn.ch> References: <20250918-imx8mp-prt8ml-v2-0-3d84b4fe53de@pengutronix.de> <20250918-imx8mp-prt8ml-v2-3-3d84b4fe53de@pengutronix.de> <20250918165156.10e55b85@erd003.prtnl> <7f1d9289-4102-4db9-a2bb-ff270e8871b7@lunn.ch> Organization: Protonic Holland X-Mailer: Claws Mail 4.3.1 (GTK 3.24.49; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Thu, 18 Sep 2025 17:04:55 +0200 Andrew Lunn wrote: > > Yes, unfortunately the SJA1105Q does not support PAUSE frames, and the i.MX8MP > > FEC isn't able to sustain 1000Mbps (only about 400ish) due to insufficient > > internal bus bandwidth. It will generate PAUSE frames, but the SJA1105Q > > ignores these, leading to packet loss, which is obviously worse than > > restricting this link to 100Mbps. Ironically both chips are from the same > > manufacturer, yet are incompatible in this regard. > > Thanks for the explanation. Maybe add a comment that the bandwidth is > limited due to the lack of flow control resulting in packet loss in > the FEC. > > Anything which looks odd deserves a comment, otherwise somebody will > question it.... Yes! This is a golden tip. Ironically what I said above is incorrect. Sorry for the noise. Ftr: I wrote this DT about 4 years ago, so my memory failed me, and a comment in the code would have saved me this embarrassment ;-) The comment above applies to the i.MX6 SoC's which had this limitation. On the i.MX8MP we had a different problem that also caused the SJA1105Q not to work reliably at 1000Mbps either. We haven't been able to find the issue, but so far this switch hasn't been able to work at 1000Mbps reliable on any platform, possibly for different reasons in each case. Best regards, -- David Jander