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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 5F797CA5FED for ; Fri, 9 Oct 2026 07:19:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Type: Content-Transfer-Encoding:MIME-Version:References:In-Reply-To:Message-ID:Date :Subject:Cc:To:From:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=a/8J9ffRImKtNVgXRfCWQ7IuyliYAcjl+4vVSs1mp0o=; b=Bc4GWT4gNvowV0jHMYBiXfQXkg rCgsjCJfHzJrerCssvNebZ691WNllJEtokksuY+eL1hy+1/QZBa53litKF5KKq450yt5ZVXGRuDOQ ituBYyLulSCD7uc5gDD0q2ba/O5YXa6UnDRjgdT7A5FNkr4ZvrLwyvqoyvVKBVLUV6qz6mqBsBkgf pj3i7Airj/enuPUHR2sLlHb6rIi5OAaGDElbWNwtFcl3eCCzYNwhI5HwsjYiW518sQUenLOL0xZ+Y QexBZ3bJOg3iYHy/D+4rL56bdY5RarHWKE6fY1IWv4uyWGLYwwJCGPGi7Nm5XRQCt/hjji1enPCwY hmJB33SA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1xF4tF-00000005i46-3nHB; Fri, 09 Oct 2026 07:19:37 +0000 Received: from gloria.sntech.de ([185.11.138.130]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1xF4tC-00000005i3V-0J2a; Fri, 09 Oct 2026 07:19:35 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=sntech.de; s=gloria202408; h=Content-Type:Content-Transfer-Encoding:MIME-Version: References:In-Reply-To:Message-ID:Date:Subject:Cc:To:From:Reply-To; bh=a/8J9ffRImKtNVgXRfCWQ7IuyliYAcjl+4vVSs1mp0o=; b=dasyinXg5c5YC9V8raqDWPImHP ZLaFAtOqeK/6eFGh99ixvboc5TRLL4LqbmI83EQEC7yFDUW7RbfmU8fWQ0h5F3wzWB/ocDRdNs7aU Mx25M1ZiXFRP1B6KsiQmYb88Yti+hdeSgb1L7I8v113gqBReOZBgVKmBp2EALwVl4oLP/4ALmSojt wdeRs8PbtPMCKyKtrLMTm8ifBggbc33keCoyCkodt+ugxhgxlLjIceV1drs09ZBSrlrY0X1rxJDQQ /MO/n3RG9Eqp8/LNKzwfQDYdUR21ZO8UCSiwjXYwbucVhOS5frUaE7RK4OTyXFa/GhNdiofR7KSzX 9kiqAF+Q==; From: Heiko Stuebner To: Rob Herring , Krzysztof Kozlowski , Conor Dooley , Liang Chen , Jun Yan Cc: Jun Yan , devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-rockchip@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] arm64: dts: rockchip: Add dma-names to RK356x UART nodes Date: Fri, 09 Oct 2026 09:19:25 +0200 Message-ID: <3055334.SvYEEZNnvj@phil> In-Reply-To: <20261009020103.364498-1-jerrysteve1101@gmail.com> References: <20261009020103.364498-1-jerrysteve1101@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20261009_001934_196751_5A4F919C X-CRM114-Status: GOOD ( 11.27 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Am Freitag, 9. Oktober 2026, 04:01:02 Mitteleurop=C3=A4ische Sommerzeit sch= rieb Jun Yan: > The RK356x UART nodes define a dmas property but omit the matching > dma-names property, so the 8250 driver fails to request a DMA channel > and falls back to PIO, logging: >=20 > of_dma_request_slave_channel: dma-names property of node > '/serial@fe650000' missing or empty >=20 > Add the missing dma-names =3D "tx", "rx" to uart0 through uart9, > matching other Rockchip SoCs such as the RK3588. >=20 > Fixes: a3adc0b9071d ("arm64: dts: rockchip: add core dtsi for RK3568 SoC") > Signed-off-by: Jun Yan Please don't do that. Uart dma can cause problems on uarts that don't use flow-control, see [0]. So the solution of choice is to only enable it for uarts connected to bluetooth on at least RK356x. Heiko [0] https://lore.kernel.org/linux-rockchip/CAMdYzYpXtMocCtCpZLU_xuWmOp2Ja_v= 0Aj0e6YFNRA-yV7u14g@mail.gmail.com/