From patchwork Mon May 10 14:53:12 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Doug Anderson X-Patchwork-Id: 433209 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=-19.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, USER_AGENT_GIT autolearn=unavailable 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 35711C433B4 for ; Mon, 10 May 2021 15:21:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 13B1461139 for ; Mon, 10 May 2021 15:21:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237583AbhEJPWu (ORCPT ); Mon, 10 May 2021 11:22:50 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46540 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237515AbhEJPW3 (ORCPT ); Mon, 10 May 2021 11:22:29 -0400 Received: from mail-pl1-x62b.google.com (mail-pl1-x62b.google.com [IPv6:2607:f8b0:4864:20::62b]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1B6E9C0610D9 for ; Mon, 10 May 2021 07:53:39 -0700 (PDT) Received: by mail-pl1-x62b.google.com with SMTP id b3so9245113plg.11 for ; Mon, 10 May 2021 07:53:39 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=NRw7CDFpS1q9ZVL6Vz48+QpNkzFGcgIXfr4kOnd5kYo=; b=O7EDDvnnwKHp59jdXm/LWuTtFAHOv3r/ayTS4x1rYRhaTr3FvFLeNrKzLei76S/Qs0 EW0uPnXwvlDNf6AD27MIvqktQW+VFQQiInlInQ5a4I/B7d7C46ZopnsEEAs8j+pVmUCr 7zw58AH7GXd6AXX0aPGsC1vxgKP8p9UoFxmWA= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=NRw7CDFpS1q9ZVL6Vz48+QpNkzFGcgIXfr4kOnd5kYo=; b=XbWET6CunOHZ8F5dbP+PuDaDLf4Qut2i9SEi/ZeQ8B9nz1xK+NCQTX7IizR4a4rrP4 lfZHPPmaPIXNjApVj4UGsf4jLtzF0Ften0X7Yr1Eta+WQVFdsDxd4bXwwlbncpIohISB oud0oZiqr9yFhjhSqZOSM7/WvzzaUZbimGPRSYl7/8gs0NGZKJ/tEIZDRK7Y8h5R3Lb7 mvlwEoVzWy8/FaY6ndJ65wV85nad7jnfOg0JqolW5Gmd/aEAnakslOhydclTezRN0HJd xmNYKIeoanwsOberlotQN3renBeVZIEp7NfQAe+pzQqP+BlM8DhzyyjGY2Zs4PN9zLbS 5Xkg== X-Gm-Message-State: AOAM53075oqgLJwFFbpOH4otiaVNq/cHfhYC7VssQdFYXftGOxsBEyKY 8pAWuaVVtvWpNURD+D3TgCiW1vpJaghxImm7 X-Google-Smtp-Source: ABdhPJyCnxKhzplFOsqDSD0HB21qizrWFUS6W8vKQx85c2pZYNKGLQ93Hmfq9eD3dG4AQCj66QrEQQ== X-Received: by 2002:a17:90a:440f:: with SMTP id s15mr42639024pjg.192.1620658418656; Mon, 10 May 2021 07:53:38 -0700 (PDT) Received: from tictac2.mtv.corp.google.com ([2620:15c:202:201:102b:59ad:66fe:cebc]) by smtp.gmail.com with ESMTPSA id bx12sm19863298pjb.1.2021.05.10.07.53.37 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 10 May 2021 07:53:38 -0700 (PDT) From: Douglas Anderson To: Bjorn Andersson Cc: Wenchao Han , Douglas Anderson , Andy Gross , Rob Herring , devicetree@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] arm64: dts: qcom: sc7180: Modify SPI_CLK voltage level for trogdor Date: Mon, 10 May 2021 07:53:12 -0700 Message-Id: <20210510075253.1.Ib4c296d6ff9819f26bcaf91e8a08729cc203fed0@changeid> X-Mailer: git-send-email 2.31.1.607.g51e8a6a459-goog MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-arm-msm@vger.kernel.org From: Wenchao Han On coachz it could be observed that SPI_CLK voltage level was only 1.4V during active transfers because the drive strength was too weak. The line hadn't finished slewing up by the time we started driving it down again. Using a drive strength of 8 lets us achieve the correct voltage level of 1.8V. Though the worst problems were observed on coachz hardware, let's do this across the board for trogdor devices. Scoping other boards shows that this makes the clk line look nicer on them too and doesn't introduce any problems. Only the clk line is adjusted, not any data lines. Because SPI isn't a DDR protocol we only sample the data lines on either rising or falling edges, not both. That means the clk line needs to toggle twice as fast as data lines so having the higher drive strength is more important there. Signed-off-by: Wenchao Han [dianders: Adjust author real name; adjust commit message] Signed-off-by: Douglas Anderson --- arch/arm64/boot/dts/qcom/sc7180-trogdor.dtsi | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/arm64/boot/dts/qcom/sc7180-trogdor.dtsi b/arch/arm64/boot/dts/qcom/sc7180-trogdor.dtsi index 24d293ef56d7..c11e07959a63 100644 --- a/arch/arm64/boot/dts/qcom/sc7180-trogdor.dtsi +++ b/arch/arm64/boot/dts/qcom/sc7180-trogdor.dtsi @@ -981,6 +981,7 @@ pinconf { &qspi_clk { pinconf { pins = "gpio63"; + drive-strength = <8>; bias-disable; }; };