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 X-Spam-Level: * X-Spam-Status: No, score=1.7 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_DBL_ABUSE_MALW autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 80929C35247 for ; Mon, 3 Feb 2020 19:10:33 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 52FFD2082E for ; Mon, 3 Feb 2020 19:10:33 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="GpetUOKU" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 52FFD2082E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.de Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender:Content-Type:Cc: List-Subscribe:List-Help:List-Post:List-Archive:List-Unsubscribe:List-Id: MIME-Version:References:In-Reply-To:Date:To:From:Subject:Message-ID:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=IuqUcI4/GBwiCkfCvzjw95+UDXakjay+DP+QFl4rNLU=; b=GpetUOKUfjpWv9CbhLNEVqD1Q SmbZSFag18PsrsoPoAzUH2BVFfgavtWC+N9xJ85UVcsny3QDuGRsLxty9V3U/iMVceHIpxPQrBcng Qn/DSnYYhXwUAIqIWXyzMf/dQnlb7WUt1exzWTGxUejVKDGXq2YyD2hIRIQSF5T+C+ToY//ukXEHX JurT+sC/wuYj1U4zyDSsKCp6wh1DNBhEI8U31hyK/6nwSebEN7bZZ8nMPIyuvLVxwtVStjFgEThEL IUfmH7pe5aFp7rrh84enXMLArkIp7QFe+wgKdcJzpnEepUYLmWyAgYwTF46yDkrFMSFfZhea4kUOc 4lISVttCQ==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1iyh75-0007Cq-NE; Mon, 03 Feb 2020 19:10:27 +0000 Received: from mx2.suse.de ([195.135.220.15]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1iyh72-0007CQ-Sj; Mon, 03 Feb 2020 19:10:26 +0000 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id 056FFB061; Mon, 3 Feb 2020 19:10:23 +0000 (UTC) Message-ID: Subject: Re: [PATCH] serial: 8250_early: Add earlycon for BCM2835 aux uart From: Nicolas Saenz Julienne To: Lukas Wunner Date: Mon, 03 Feb 2020 20:10:21 +0100 In-Reply-To: <20200131152414.73tgwsfhzgu4apkx@wunner.de> References: <20200128141958.vwbxoqglt5gw4xj5@wunner.de> <20200131152414.73tgwsfhzgu4apkx@wunner.de> User-Agent: Evolution 3.34.3 MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200203_111025_218303_575A024D X-CRM114-Status: GOOD ( 22.23 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Matthias Brugger , Scott Branden , gregkh@linuxfoundation.org, jslaby@suse.com, linux-kernel@vger.kernel.org, Ray Jui , Stephen Boyd , Florian Fainelli , bcm-kernel-feedback-list@broadcom.com, linux-rpi-kernel@lists.infradead.org, linux-serial@vger.kernel.org, matthias.bgg@kernel.org, Matthias Brugger , linux-arm-kernel@lists.infradead.org Content-Type: multipart/mixed; boundary="===============2536807104901709037==" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org --===============2536807104901709037== Content-Type: multipart/signed; micalg="pgp-sha256"; protocol="application/pgp-signature"; boundary="=-rxZ/SqVaphyyjrFeqQty" --=-rxZ/SqVaphyyjrFeqQty Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Fri, 2020-01-31 at 16:24 +0100, Lukas Wunner wrote: > On Thu, Jan 30, 2020 at 05:11:55PM +0100, Nicolas Saenz Julienne wrote: > > BTW did you had the oportunity to have a go at the patch? >=20 > I've just performed a quick test and it doesn't work for me. > If I add stdout-path =3D "serial1:115200n8"; to the chosen node, > I only get a regular console with this patch, not an earlycon. That's surprising, you're using u-boot isn't it? and the upstream device tr= ee? > > > The problem is that in mainline, bcm2835_defconfig contains: > > > CONFIG_CPU_FREQ_DEFAULT_GOV_CONSERVATIVE=3Dy > > >=20 > > > Likewise in the Foundation's downstream tree, bcmrpi_defconfig as wel= l > > > as bcm2711_defconfig and bcm2709_defconfig contain: > > > CONFIG_CPU_FREQ_DEFAULT_GOV_POWERSAVE=3Dy > > >=20 > > > In contrast to this, we set the following on Revolution Pi devices: > > > CONFIG_CPU_FREQ_DEFAULT_GOV_PERFORMANCE=3Dy > > >=20 > > > Downclocking influences not only the uart1 baud rate but also the > > > spi0 clock. We attach Ethernet chips to spi0, throughput was > > > significantly worse with the ondemand governor (which is what we > > > used previously). We felt that maximum Ethernet performance > > > outweighs the relatively small powersaving gains. > >=20 > > In that regard I suggest you use the upstream cpufreq driver which > > behaves properly in that regard. It disables GPU freq scaling, so as to > > change CPU frequencies without SPI/I2C/UART issues. >=20 > Okay, I'll take a look. But the uart1 baudrate will still be wrong > if the firmware downclocks because of overheating, right? You're right, it might happen. The way I understand it you're bound to leav= e the GPU at it's lower frequency if you want to use those peripherals and fo= r them to be reliable. You could technically try to empirically fine tune the= CPU thermal trip point so as to make sure the upstream kernel cpufreq downclock always kicks in before videocore's one. I'd actually like to see someone tr= y that. However short of using an RT kernel It think you'll never be 100% sur= e it can never happen. Regards, Nicolas --=-rxZ/SqVaphyyjrFeqQty Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part Content-Transfer-Encoding: 7bit -----BEGIN PGP SIGNATURE----- iQEzBAABCAAdFiEErOkkGDHCg2EbPcGjlfZmHno8x/4FAl44cB0ACgkQlfZmHno8 x/4OKwf+KvsKB8pRgfFS6tQGkcjn5+7rl7qXYEndk80sawqCUn4/ZHkxPdoqD5cO bU8iTyaNfFQQb9uq8RoWcJrFMKQJhxGe8sjDNkZNqvbTUr3oM8ltCrjVWX7D5wfG eDSxB7hZqwE+BkdJaK3G5kicCfPl21opnQwZUn7R/0e0bYIuzMu/hq1xk7XiRaLU hL30AwUY3DLZtOVEeNIeVW9TVuVdnbu219TXZjtwuD+iZ9u2xbkh83fne8s0nW7O 79/Gejgu/e5PDH3CTnbheLNpl9Fws8fGiERnwXNbAD2XSj2kOfTitCVVNK2Efup5 txMswkwfPEC1JsGHkHgANzz5Z5UOVQ== =AW10 -----END PGP SIGNATURE----- --=-rxZ/SqVaphyyjrFeqQty-- --===============2536807104901709037== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel --===============2536807104901709037==--