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=-7.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 4603EC43381 for ; Sun, 3 Mar 2019 13:19:56 +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 1534F20863 for ; Sun, 3 Mar 2019 13:19:56 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="tTjt2KtG" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1534F20863 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=sntech.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-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: 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: List-Owner; bh=m1nERbuslBhR+WFCzpa+81MO6GzzL99LZCGClCOHVCs=; b=tTjt2KtG9oAHhm qn2Ubv32s/IzsB5Tm0CrThVn/WYBOWYmqtlc91rz041Ptd2h5wQOWP1CjDo5tXP3dqLNVJsj3wS+l mVP2wA9ZBpKlCJO3F0eO7NaX43vMTnHSi9ZKFtSx3TxyVcQC+cuvFUzHacshryRpzgHXEgqn1htJW PEjuszqWM1cNd0l7dGYK11RIy/NtTucBfc4D0I21zV1MNRyxHsFXDxsfd1wYgcBwNfgXVT9Sqkotv 2McWy8nkCnqmUdyTnMrM0AALkuSbeckBFL90+fDECjmvA1k22qZ44N5A8W8P0X0EWDBTIGU1c5kst tgFnu3pG82bHHexjeh9A==; 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 1h0R1y-00052w-CQ; Sun, 03 Mar 2019 13:19:50 +0000 Received: from gloria.sntech.de ([185.11.138.130]) by bombadil.infradead.org with esmtps (Exim 4.90_1 #2 (Red Hat Linux)) id 1h0R1t-000528-IV; Sun, 03 Mar 2019 13:19:47 +0000 Received: from p54b26aa0.dip0.t-ipconnect.de ([84.178.106.160] helo=phil.localnet) by gloria.sntech.de with esmtpsa (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1h0R1p-0004tT-Iw; Sun, 03 Mar 2019 14:19:41 +0100 From: Heiko Stuebner To: Katsuhiro Suzuki Subject: Re: [PATCH] arm64: dts: rockchip: decrease rising edge time of UART2 Date: Sun, 03 Mar 2019 14:19:40 +0100 Message-ID: <1623469.Hy6pdcMFRX@phil> In-Reply-To: <20190303122705.27094-1-katsuhiro@katsuster.net> References: <20190303122705.27094-1-katsuhiro@katsuster.net> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190303_051945_765631_8FF62F70 X-CRM114-Status: GOOD ( 18.57 ) 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: linux-rockchip@lists.infradead.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi, Am Sonntag, 3. M=E4rz 2019, 13:27:05 CET schrieb Katsuhiro Suzuki: > 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(-) your changing a core rk3399 property here, so I'd really like to get input from other board stakeholders on this before applying a core change. Could you either include the submitters of other rk3399-boards in the recipient list so that they're aware or limit the change to rockpro64 for the time being (aka overriding the property in the board-dts) please? Thanks Heiko > diff --git a/arch/arm64/boot/dts/rockchip/rk3399.dtsi b/arch/arm64/boot/d= ts/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 =3D <8>; > }; > = > + pcfg_pull_up_12ma: pcfg-pull-up-12ma { > + bias-pull-up; > + drive-strength =3D <12>; > + }; > + > pcfg_pull_up_18ma: pcfg-pull-up-18ma { > bias-pull-up; > drive-strength =3D <18>; > @@ -2521,8 +2526,8 @@ > uart2c { > uart2c_xfer: uart2c-xfer { > rockchip,pins =3D > - <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>; > }; > }; > = > = _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel