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 44BCDEB64D7 for ; Sun, 18 Jun 2023 13:58:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229844AbjFRN6I (ORCPT ); Sun, 18 Jun 2023 09:58:08 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46672 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229779AbjFRN6G (ORCPT ); Sun, 18 Jun 2023 09:58:06 -0400 Received: from aposti.net (aposti.net [89.234.176.197]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 671211BF; Sun, 18 Jun 2023 06:58:05 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=crapouillou.net; s=mail; t=1687096683; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=YFvP7ex7sh59x2Zu10sumdOcBtAoUqyi0bcCYgQlGWg=; b=oeomZ+Lh4LsIYrRa1ueU6sp5sjcBeRBkiVFe96qQ2aTd4+WbMBrxDdDMo8cSC5L1zO3WJr R8mbbMaWOOFJpjmdqGrYLhPV4wZzvpBR8jpineG40OwyjgB7QSINuDpOXIEKiY0GOh2ozK 98VCgkq/wLOkOaR8tFHJ+6mmUggrQq4= Message-ID: <5511fba10119cdc08a18ea2cca98fed343f9cd33.camel@crapouillou.net> Subject: Re: [PATCH 0/9] MIPS: CI20: Add WiFi / Bluetooth support From: Paul Cercueil To: "H. Nikolaus Schaller" Cc: list@opendingux.net, Rob Herring , Krzysztof Kozlowski , linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, Conor Dooley , linux-mips@vger.kernel.org, Thomas Bogendoerfer , Paul Boddie , Paul Burton , Christophe Branchereau Date: Sun, 18 Jun 2023 15:58:01 +0200 In-Reply-To: References: <20230615084006.79194526F801@goldelico.com> <5EF6B0D2-2B84-4C98-B799-88062E035EC1@goldelico.com> <43DCEEA5-C013-44BE-85C7-D61A980B0EA5@goldelico.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi All, [...] > Looking at the JZ4780_DS.PDF file, the SoC actually wants 1.1V so the > DT is not wrong - in theory. But in practice it does not work, as you > experienced yourself. However, if the ACT8600 defaults to 1.2V, or if > the bootloader configures it to 1.2V, I would think that this is > actually a voltage that the SoC can handle - otherwise the SoC would > be > overvolted until the kernel starts, and the board design would be > flawed. >=20 > I measured that the old 3.x kernel keeps the SoC voltage at 1.2V, so > it > sounds like a better default. Therefore the fix here would be to > raise > the DCDC1 regulator to 1.2V. >=20 > I'll send a patch later today. After a talk with Christophe (Cc'd), I changed my mind. A +100 mV overvolt is a *huge* step up, and although the SoC doesn't burst into flames, it could very well reduce its life span. I used to have huge stability issues (kernel not booting to userspace half the times, or just plain reboots after a few minutes of uptime) and I now realize it's because I was running the core at 1.1V, because these issues disappeared the moment I switched to 1.2V. However, I am now running at 1.125 volts, which is just 25mV above the nominal voltage - and it's been extremely stable so far. Nikolaus: could you test at 1.125 volts? If it's stable for you as well, I'd suggest to use this as the new default. Paul (Burton): As you wrote most of the drivers (and uboot?) for the board, do you know why VDDCORE was set to 1.2V? Cheers, -Paul