From patchwork Sun Mar 3 12:27:05 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Katsuhiro Suzuki X-Patchwork-Id: 10837019 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id D8FE41575 for ; Sun, 3 Mar 2019 12:27:25 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id ADD882A0C9 for ; Sun, 3 Mar 2019 12:27:25 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 9D38B2A1E9; Sun, 3 Mar 2019 12:27:25 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 130B42A0C9 for ; Sun, 3 Mar 2019 12:27:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:Message-Id:Date:Subject:To :From:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:References: List-Owner; bh=tkiSsb+Gu7/bNdxyoioEIsHVXROeo/uCVgtf5rfyhM4=; b=L15Wb8jMoILFPN P2MfYqoEaaGh1T4scdEu4iaXF/OeNBrOwM4JQOeWeOx+DWS22oLsLfIzyCOi21NURCF0hvyWH+8wN j0ZauVo4NCvygeMQHcafzfuv8oR5L5ugxgqlKXalcojnvBcsi0XC/noDfz73kw/SjZuI/YkT0sF0Q 6m2fhmwOZWeCIye+gbxlhMoNhePojM66fS5908eLSqsvR6y+ZySxOIazTFjc/EKg8BxLSB5/w0xxE nNkVXV1GJNXpw8lwZ/0MOdWoceY0s673dC/2C8+K1/Ce9o7UcBQ7LCXj34YJtNm5zOSi+td31DDdr vrSzSX84hStNNtTQgBHg==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1h0QDA-000787-IJ; Sun, 03 Mar 2019 12:27:20 +0000 Received: from www1102.sakura.ne.jp ([219.94.129.142]) by bombadil.infradead.org with esmtps (Exim 4.90_1 #2 (Red Hat Linux)) id 1h0QD6-00076v-LJ; Sun, 03 Mar 2019 12:27:18 +0000 Received: from fsav405.sakura.ne.jp (fsav405.sakura.ne.jp [133.242.250.104]) by www1102.sakura.ne.jp (8.15.2/8.15.2) with ESMTP id x23CR9XT064824; Sun, 3 Mar 2019 21:27:09 +0900 (JST) (envelope-from katsuhiro@katsuster.net) Received: from www1102.sakura.ne.jp (219.94.129.142) by fsav405.sakura.ne.jp (F-Secure/fsigk_smtp/530/fsav405.sakura.ne.jp); Sun, 03 Mar 2019 21:27:09 +0900 (JST) X-Virus-Status: clean(F-Secure/fsigk_smtp/530/fsav405.sakura.ne.jp) Received: from localhost.localdomain (119.104.232.153.ap.dti.ne.jp [153.232.104.119]) (authenticated bits=0) by www1102.sakura.ne.jp (8.15.2/8.15.2) with ESMTPSA id x23CR61p064800 (version=TLSv1.2 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Sun, 3 Mar 2019 21:27:09 +0900 (JST) (envelope-from katsuhiro@katsuster.net) From: Katsuhiro Suzuki To: Heiko Stuebner , linux-rockchip@lists.infradead.org Subject: [PATCH] arm64: dts: rockchip: decrease rising edge time of UART2 Date: Sun, 3 Mar 2019 21:27:05 +0900 Message-Id: <20190303122705.27094-1-katsuhiro@katsuster.net> X-Mailer: git-send-email 2.20.1 MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190303_042716_950243_C5FAEDD4 X-CRM114-Status: GOOD ( 10.31 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Katsuhiro Suzuki , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Virus-Scanned: ClamAV using ClamSMTP This patch increases drive strength of UART2 from 3mA to 12mA for getting more faster rising edge. RockPro64 is using a very high speed rate (1.5Mbps) for UART2. In this setting, a bit width of UART is about 667ns. In my environment (RockPro64 UART2 with FTDI FT232RL UART-USB converter), falling time of RockPro64 UART2 is 40ns, but riging time is over 650ns. So UART receiver will get wrong data, because receiver read intermediate data of rising edge. Rising time becomes 300ns from 650ns if apply this patch. This is not perfect solution but better than now. Signed-off-by: Katsuhiro Suzuki --- arch/arm64/boot/dts/rockchip/rk3399.dtsi | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/arch/arm64/boot/dts/rockchip/rk3399.dtsi b/arch/arm64/boot/dts/rockchip/rk3399.dtsi index beaa92744a64..e3c8f91ead50 100644 --- a/arch/arm64/boot/dts/rockchip/rk3399.dtsi +++ b/arch/arm64/boot/dts/rockchip/rk3399.dtsi @@ -2000,6 +2000,11 @@ drive-strength = <8>; }; + pcfg_pull_up_12ma: pcfg-pull-up-12ma { + bias-pull-up; + drive-strength = <12>; + }; + pcfg_pull_up_18ma: pcfg-pull-up-18ma { bias-pull-up; drive-strength = <18>; @@ -2521,8 +2526,8 @@ uart2c { uart2c_xfer: uart2c-xfer { rockchip,pins = - <4 RK_PC3 RK_FUNC_1 &pcfg_pull_up>, - <4 RK_PC4 RK_FUNC_1 &pcfg_pull_none>; + <4 RK_PC3 RK_FUNC_1 &pcfg_pull_up_12ma>, + <4 RK_PC4 RK_FUNC_1 &pcfg_pull_none_12ma>; }; };