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 4FA9CC433F5 for ; Thu, 3 Feb 2022 17:25:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1352803AbiBCRZw (ORCPT ); Thu, 3 Feb 2022 12:25:52 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42522 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1352472AbiBCRZw (ORCPT ); Thu, 3 Feb 2022 12:25:52 -0500 Received: from metis.ext.pengutronix.de (metis.ext.pengutronix.de [IPv6:2001:67c:670:201:290:27ff:fe1d:cc33]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0B97FC061714 for ; Thu, 3 Feb 2022 09:25:52 -0800 (PST) Received: from gallifrey.ext.pengutronix.de ([2001:67c:670:201:5054:ff:fe8d:eefb] helo=[127.0.0.1]) by metis.ext.pengutronix.de with esmtp (Exim 4.92) (envelope-from ) id 1nFfrd-0002xF-6f; Thu, 03 Feb 2022 18:25:45 +0100 Message-ID: Date: Thu, 3 Feb 2022 18:25:43 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.5.0 From: Ahmad Fatoum Subject: Re: [PATCH 00/16] STM32 configure UART nodes for DMA To: Erwan Le Ray , Alexandre Torgue Cc: Rob Herring , Maxime Coquelin , Manivannan Sadhasivam , Marek Vasut , Marcin Sloniewski , Jagan Teki , devicetree@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Pengutronix Kernel Team References: <20220203171114.10888-1-erwan.leray@foss.st.com> Content-Language: en-US In-Reply-To: <20220203171114.10888-1-erwan.leray@foss.st.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-SA-Exim-Connect-IP: 2001:67c:670:201:5054:ff:fe8d:eefb X-SA-Exim-Mail-From: a.fatoum@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: devicetree@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org Hello Erwan, On 03.02.22 18:10, Erwan Le Ray wrote: > Add DMA configuration to UART nodes in stm32mp15x (SOC level) and > remove it at board level to keep current PIO behavior when needed. > For stm32-ed1 and stm32-dkx boards, UART4 (console) and UART7 > (no HW flow control pin available) are kept in PIO mode, while USART3 > is now configured in DMA mode. > UART4 (console UART) has to be kept in irq mode, as DMA support for > console has been removed from the driver by commit e359b4411c28 > ("serial: stm32: fix threaded interrupt handling"). Do I understand correctly that your first patch breaks consoles of most/all boards, because they will briefly use DMA, which is refused by the stm32-usart driver and then you add a patch for each board to fix that breakage? Such intermittent breakage makes bisection a hassle. /delete-property/ is a no-op when the property doesn't exist, so you could move the first patch to the very end to avoid intermittent breakage. I also think that the driver's behavior is a bit harsh. I think it would be better for the UART driver to print a warning and fall back to PIO for console instead of outright refusing and rendering the system silent. That's not mutually exclusive with your patch series here, of course. Cheers, Ahmad > > For other stm32mp15x-based boards, current configuration is kept for > all UART instances. > > Erwan Le Ray (16): > ARM: dts: stm32: add DMA configuration to UART nodes on stm32mp151 > ARM: dts: stm32: keep uart4 behavior on stm32mp157c-ed1 > ARM: dts: stm32: keep uart4 and uart7 behavior on stm32mp15xx-dkx > ARM: dts: stm32: keep uart4 behavior on icore-stm32mp1-ctouch2 > ARM: dts: stm32: keep uart4 behavior on icore-stm32mp1-edimm2.2 > ARM: dts: stm32: keep uart4 behavior on stm32mp157a-iot-box > ARM: dts: stm32: keep uart nodes behavior on stm32mp1-microdev2.0-of7 > ARM: dts: stm32: keep uart nodes behavior on stm32mp1-microdev2.0 > ARM: dts: stm32: keep uart nodes behavior on stm32mp157a-stinger96 > ARM: dts: stm32: keep uart4 behavior on stm32mp157c-lxa-mc1 > ARM: dts: stm32: keep uart4 behavior on stm32mp157c-odyssey > ARM: dts: stm32: keep uart nodes behavior on stm32mp15xx-dhcom-drc02 > ARM: dts: stm32: keep uart nodes behavior on stm32mp15xx-dhcom-pdk2 > ARM: dts: stm32: keep uart nodes behavior on stm32mp15xx-dhcom-picoitx > ARM: dts: stm32: keep uart4 behavior on stm32mp15xx-dhcom-som > ARM: dts: stm32: keep uart nodes behavior on > stm32mp15xx-dhcor-avenger96 > > arch/arm/boot/dts/stm32mp151.dtsi | 21 +++++++++++++++++++ > .../stm32mp157a-icore-stm32mp1-ctouch2.dts | 2 ++ > .../stm32mp157a-icore-stm32mp1-edimm2.2.dts | 2 ++ > arch/arm/boot/dts/stm32mp157a-iot-box.dts | 2 ++ > ...157a-microgea-stm32mp1-microdev2.0-of7.dts | 4 ++++ > ...32mp157a-microgea-stm32mp1-microdev2.0.dts | 4 ++++ > arch/arm/boot/dts/stm32mp157a-stinger96.dtsi | 6 ++++++ > arch/arm/boot/dts/stm32mp157c-ed1.dts | 2 ++ > arch/arm/boot/dts/stm32mp157c-lxa-mc1.dts | 2 ++ > arch/arm/boot/dts/stm32mp157c-odyssey.dts | 2 ++ > .../arm/boot/dts/stm32mp15xx-dhcom-drc02.dtsi | 4 ++++ > arch/arm/boot/dts/stm32mp15xx-dhcom-pdk2.dtsi | 4 ++++ > .../boot/dts/stm32mp15xx-dhcom-picoitx.dtsi | 4 ++++ > arch/arm/boot/dts/stm32mp15xx-dhcom-som.dtsi | 2 ++ > .../boot/dts/stm32mp15xx-dhcor-avenger96.dtsi | 6 ++++++ > arch/arm/boot/dts/stm32mp15xx-dkx.dtsi | 4 ++++ > 16 files changed, 71 insertions(+) > -- Pengutronix e.K. | | Steuerwalder Str. 21 | http://www.pengutronix.de/ | 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |