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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id A2C50C77B62 for ; Tue, 4 Apr 2023 15:40:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234616AbjDDPkq (ORCPT ); Tue, 4 Apr 2023 11:40:46 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34348 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235788AbjDDPkf (ORCPT ); Tue, 4 Apr 2023 11:40:35 -0400 Received: from vps.xff.cz (vps.xff.cz [195.181.215.36]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6464F5259; Tue, 4 Apr 2023 08:40:21 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=xff.cz; s=mail; t=1680622817; bh=gUC07j0BF6Ats3pO8KtZR2khuJGxBN6yLNKDq0ZvG30=; h=Date:From:To:Cc:Subject:X-My-GPG-KeyId:References:From; b=INqbPpsh/s/pyXwwSr3hAKvrhnRGaA9cMvlZ93RrKGcfJFPGWN20zK6g1VSjZpqex 4FXM4fWK4Amlp3oeQBN9XLKYT+xwH4j7d7+TvRFW8l2TCfytSWp6vpnm3J8ypwmRIX kwF8qWypcZFyJJkX9LdNAihL+BOQnlcQoZDNZaBI= Date: Tue, 4 Apr 2023 17:40:17 +0200 From: =?utf-8?Q?Ond=C5=99ej?= Jirman To: Javier Martinez Canillas Cc: Heiko =?utf-8?Q?St=C3=BCbner?= , linux-kernel@vger.kernel.org, Peter Robinson , Caleb Connolly , Jarrah Gosbell , Krzysztof Kozlowski , Martijn Braam , Rob Herring , Tom Fitzhenry , devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-rockchip@lists.infradead.org Subject: Re: [PATCH] arm64: dts: rockchip: Change serial baud rate for Pinephone Pro to 1.5 MB Message-ID: <20230404154017.7n6rcgqyv3edfahd@core> Mail-Followup-To: =?utf-8?Q?Ond=C5=99ej?= Jirman , Javier Martinez Canillas , Heiko =?utf-8?Q?St=C3=BCbner?= , linux-kernel@vger.kernel.org, Peter Robinson , Caleb Connolly , Jarrah Gosbell , Krzysztof Kozlowski , Martijn Braam , Rob Herring , Tom Fitzhenry , devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-rockchip@lists.infradead.org X-My-GPG-KeyId: EBFBDDE11FB918D44D1F56C1F9F0A873BE9777ED References: <20230403175937.2842085-1-javierm@redhat.com> <3738011.44csPzL39Z@diego> <20230404123646.5iiznbhnyoama5pp@core> <87r0szd9q2.fsf@minerva.mail-host-address-is-not-set> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <87r0szd9q2.fsf@minerva.mail-host-address-is-not-set> Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org On Tue, Apr 04, 2023 at 04:04:53PM +0200, Javier Martinez Canillas wrote: > Ondřej Jirman writes: > > > On Tue, Apr 04, 2023 at 09:51:11AM +0200, Heiko Stübner wrote: > >> Hi, > >> > >> Am Montag, 3. April 2023, 19:59:37 CEST schrieb Javier Martinez Canillas: > >> > This baud rate is set for the device by mainline u-boot and is also what > >> > is set in the Pinebook Pro Device Tree, which is a device similar to the > >> > PinePhone Pro but with a different form factor. > >> > > >> > Otherwise, the baud rate of the firmware and Linux don't match by default > >> > and a 'console=ttyS2,1500000n8' kernel command line parameter is required > >> > to have proper output for both. > >> > >> The interesting question is always if this will break someone else's setup. > >> I've never really understood the strange setting of 1.5MBps, but on the > >> other hand it _is_ a reality on most boards. > > > > Normal users of the phone probably run with UART console disabled, because > > UART is muxed with audio jack output and to enable it they have to add > > console=ttyS2 to the kernel command line and flip a physical switch inside > > the phone. > > > > Fortunately, not sepcifying stdout-path baud rate in the options part > > of the string, will make the serial driver probe for the baud rate from > > the previous boot stage and make the user happy by keeping whatever was > > already set in the bootloader. > > > > As mentioned in the first email of this thread, I tried that but it didn't > work for me. Either using stdout-path = "serial2"; or stdout-path = &uart2; > gives me no serial output with console=ttyS2, I needed to specify the baud > rate explicitly (i.e: console=ttyS2,1500000n8). > > > https://elixir.bootlin.com/linux/latest/source/drivers/tty/serial/8250/8250_port.c#L3496 > > > > Is that helper really used by the serial driver in the PinePhone Pro? > (drivers/tty/serial/8250/8250_dw.c), I was meaning to dig why just ttyS2 > was not working but decided that could be a follow-up patch. It's called by univ8250_console_setup in 8250_core.c But looking at it again, this may only be used to match console=uart. https://elixir.bootlin.com/linux/latest/source/drivers/tty/serial/8250/8250_core.c#L638 Bummer. > Since chaging to 1.5 MBps seemed to have merits on its own, decided to > post this patch anyways in the meantime. > > > So we can make the kernel just keep the baudrate setup from the previous > > boot stage by: > > > > stdout-path = "serial2"; > > > > Did it work for you? Maybe I'm doing something silly but as mentioned it > didn't work for me with upstream u-boot. I was just eyeballing the code. I didn't test it. kind regards, o. > > regards, > > o. > > > > -- > Best regards, > > Javier Martinez Canillas > Core Platforms > Red Hat >