From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from phobos.denx.de (phobos.denx.de [85.214.62.61]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id D401EC4332F for ; Tue, 12 Dec 2023 16:21:41 +0000 (UTC) Received: from h2850616.stratoserver.net (localhost [IPv6:::1]) by phobos.denx.de (Postfix) with ESMTP id 5388B8783F; Tue, 12 Dec 2023 17:21:38 +0100 (CET) Authentication-Results: phobos.denx.de; dmarc=pass (p=reject dis=none) header.from=bootlin.com Authentication-Results: phobos.denx.de; spf=pass smtp.mailfrom=u-boot-bounces@lists.denx.de Authentication-Results: phobos.denx.de; dkim=pass (2048-bit key; unprotected) header.d=bootlin.com header.i=@bootlin.com header.b="TEC8JnMH"; dkim-atps=neutral Received: by phobos.denx.de (Postfix, from userid 109) id 4A1C98783B; Tue, 12 Dec 2023 17:21:36 +0100 (CET) Received: from relay9-d.mail.gandi.net (relay9-d.mail.gandi.net [217.70.183.199]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by phobos.denx.de (Postfix) with ESMTPS id EEDB0871CE for ; Tue, 12 Dec 2023 17:21:33 +0100 (CET) Authentication-Results: phobos.denx.de; dmarc=pass (p=reject dis=none) header.from=bootlin.com Authentication-Results: phobos.denx.de; spf=pass smtp.mailfrom=miquel.raynal@bootlin.com Received: by mail.gandi.net (Postfix) with ESMTPSA id 4BEA4FF80F; Tue, 12 Dec 2023 16:21:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=gm1; t=1702398093; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=306X9wnm4HWDhBuGesCZC3/mQvsgbS1w6bVwhNlCpcQ=; b=TEC8JnMH7+5jgB7oECZo03iXFCjz4fwpwoqBQPsIbyugzW1t6/PepXnlaNepL4/CLq/oP4 2UzpbI3hhdB5IFEkdL4BgeTtlXVWRU64xHXwiAELfWPntTQtQlaqcGIEy/J/fTgWZ/b8vd gXh10ZYuzqcim/dnrU67Doml80kqGVi904MJ0ijwvg7GPaPhUqV54zmfHKeTPkTKYVRdhV wKSChkfEuMh1KDZm4YRG1m0kV9dXbKhdT+c+IqeypaaYH+A5tPqP2wCVot/fhKRe0GLYrh BxQZc8LTblAdkbn4cFE7EUHbznx2w4ghqaRt4kLOOsfTv9sAhe/REfs1tZz5qw== Date: Tue, 12 Dec 2023 17:21:30 +0100 From: Miquel Raynal To: Fabio Estevam Cc: Markus Niebel , u-boot@lists.denx.de, Thomas Petazzoni , Alexander Stein Subject: Re: [PATCH] tqma6: Fix DDR configuration Message-ID: <20231212172130.2193caea@xps-13> In-Reply-To: References: <20231117150044.1792080-1-miquel.raynal@bootlin.com> Organization: Bootlin X-Mailer: Claws Mail 4.0.0 (GTK+ 3.24.33; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-GND-Sasl: miquel.raynal@bootlin.com X-BeenThere: u-boot@lists.denx.de X-Mailman-Version: 2.1.39 Precedence: list List-Id: U-Boot discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: u-boot-bounces@lists.denx.de Sender: "U-Boot" X-Virus-Scanned: clamav-milter 0.103.8 at phobos.denx.de X-Virus-Status: Clean Hi Fabio, festevam@gmail.com wrote on Tue, 12 Dec 2023 13:11:53 -0300: > On Fri, Nov 17, 2023 at 1:50=E2=80=AFPM Miquel Raynal wrote: > > > > Initially investigating a Linux network issue causing a lot of drop and > > poor network performances on a custom system based on a TQMA6A module > > (based on an iMX6Q), [1st link below]. > > > > I eventually correlated my observations with a contention at the NIC > > level when in concurrency with the graphics pipeline. Troubleshooting > > this in the kernel lead to disabling DMA bursts accesses made by the IPU > > in order to avoid triggering the QoS at the interconnect level, reducing > > from 50 to 10% the drop rate on eth0, [2nd link below]. The solution > > worked on my setup but not on others, which still suffered from > > abnormally high drop rates even with this "fix". > > > > After looking a while into TQ Systems BSP I figured out a number of > > differences in recent U-Boot out-of-tree patches they had in their > > repository [3rd link]. Parsing the differences one after the other lead > > me to this final solution. > > > > The reset pad of the DDR controller was apparently misconfigured, Bit > > 18-19 picturing the "DDR select field". The current value b11 is > > reserved. The only defined value as of version 6 of the iMX6Q manual was > > b00 "DDR3 and LPDDR2 mode". In practice no register difference has been > > spotted after changing this configuration but all issues tracked thus > > far just vanished. All previous fixes have been proven irrelevant. Just > > clearing this field solved all our network issues and the drop rate as > > measured by iperf3 felt back to 0%. > > > > Link: https://lore.kernel.org/netdev/20231012193410.3d1812cf@xps-13/ > > Link: https://lists.freedesktop.org/archives/dri-devel/2023-October/428= 251.html > > Link: https://github.com/tq-systems/u-boot-tqmaxx/commit/15eb6abbefbf69= 16c28467b85485911dad3da6bc > > Signed-off-by: Miquel Raynal =20 >=20 > Applied, thanks. Thanks a lot. Any chances you would have access to additional information to explain how the network vs video pipeline interact without this patch? I am eager to understand. Cheers, Miqu=C3=A8l