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 B4A8BC433EF for ; Thu, 10 Mar 2022 22:35:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232159AbiCJWgB (ORCPT ); Thu, 10 Mar 2022 17:36:01 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33908 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240993AbiCJWgA (ORCPT ); Thu, 10 Mar 2022 17:36:00 -0500 Received: from mail-pg1-x536.google.com (mail-pg1-x536.google.com [IPv6:2607:f8b0:4864:20::536]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A7E51BD89D for ; Thu, 10 Mar 2022 14:34:58 -0800 (PST) Received: by mail-pg1-x536.google.com with SMTP id 132so5904763pga.5 for ; Thu, 10 Mar 2022 14:34:58 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=dm3qB2w2lQ7IFy1ipeKnHCOmhqitdfZXH/ycCypXYJA=; b=XbtHN78KIecFW+02Yyb63lZj4KZ2A9h4133DWVgegrpcThbSKDbzoYlFJPUlH5aMKW AjdapHStDHVE0xYa01ndPaYUTm8iT6/QuKTi2DPbu5LWDW8PSuM67v9LSoIYV99kPOyv t2m27yiE+DisfL7G6lcgeyzawilqE1zNRz0bI= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=dm3qB2w2lQ7IFy1ipeKnHCOmhqitdfZXH/ycCypXYJA=; b=MDzm/BbvuNCfTahJfCIwhD7MmKHdLI5PCx5npQ9wJRBR708TTgEFlBKlTSMAIawZXF ufVSO+RIW92xp/64eWJGzdwhvICJYOafwVocBDnqV9INq8awppRRkQ3dn0SpMVont8dr c+QJVIMZ/6O/mLxzQo5OGS5DWGYn0QOcDFKpjSeQuRVEqMaEsyZfvvlIJVqYANJE0xA3 Q8EOdLrZN8D1E5dxsKGjzlVh2/Mh1ia3YMFsIHn0WGnDnQNR7btOCdCNu6VMawQCR1Mg itEFvo9OKmXKQwskVw/7oio7t+WGUEQ2/ZV4i5u1dJ0OU4bhjTZ9FJpSnLj3wC9gIDA7 1JzA== X-Gm-Message-State: AOAM53153Tn94EeXCJ/1xZ0eJhWMd0ag5QEjyi695d4zEzy636aIyCgU 7036QiQ5V6GkVvp7n5wUPvAYSg== X-Google-Smtp-Source: ABdhPJy1z6bn6NBQfuRdnkrdCb5mXCccJv1Spi5pKAOp4pz2vxeEh5T0s6tYVvmFaKZb0Eg8n9tp7g== X-Received: by 2002:a63:ad47:0:b0:373:4c14:35e2 with SMTP id y7-20020a63ad47000000b003734c1435e2mr5813069pgo.67.1646951698203; Thu, 10 Mar 2022 14:34:58 -0800 (PST) Received: from localhost ([2620:15c:202:201:60f0:9f89:56be:75e9]) by smtp.gmail.com with UTF8SMTPSA id d11-20020a056a0010cb00b004e1b76b09c0sm7991122pfu.74.2022.03.10.14.34.57 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 10 Mar 2022 14:34:57 -0800 (PST) Date: Thu, 10 Mar 2022 14:34:56 -0800 From: Matthias Kaehlcke To: Douglas Anderson Cc: Bjorn Andersson , Stephen Boyd , Andy Gross , Rob Herring , devicetree@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] arm64: dts: qcom: sc7280-herobrine: Fix PCIe regulator glitch at bootup Message-ID: References: <20220310130429.1.Id41fda1d7f5d9230bc45c1b85b06b0fb0ddd29af@changeid> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20220310130429.1.Id41fda1d7f5d9230bc45c1b85b06b0fb0ddd29af@changeid> Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org On Thu, Mar 10, 2022 at 01:04:34PM -0800, Douglas Anderson wrote: > While scoping signals, we found that the PCIe signals weren't > compliant at bootup. Specifically, the bootloader was setting up PCIe > and leaving it configured, then jumping to the kernel. The kernel was > turning off the regulator while leaving the PCIe clock running, which > was a violation. > > In the regulator bindings (and the Linux kernel driver that uses > them), there's currently no way to specify that a GPIO-controlled > regulator should keep its state at bootup. You've got to pick either > "on" or "off". Let's switch it so that the PCIe regulator defaults to > "on" instead of "off". This should be a much safer way to go and > avoids the timing violation. The regulator will still be turned off > later if there are no users. > > Signed-off-by: Douglas Anderson Reviewed-by: Matthias Kaehlcke