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=-9.0 required=3.0 tests=BAYES_00,INCLUDES_CR_TRAILER, MAILING_LIST_MULTI,SPF_HELO_NONE,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 E83ECC63777 for ; Mon, 23 Nov 2020 16:59:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9225F20756 for ; Mon, 23 Nov 2020 16:59:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388169AbgKWQ7D (ORCPT ); Mon, 23 Nov 2020 11:59:03 -0500 Received: from mail-ej1-f68.google.com ([209.85.218.68]:44355 "EHLO mail-ej1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729482AbgKWQ7D (ORCPT ); Mon, 23 Nov 2020 11:59:03 -0500 Received: by mail-ej1-f68.google.com with SMTP id k9so9490095ejc.11; Mon, 23 Nov 2020 08:59:01 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=WzvwGaD9/OHMgznZpLRtc18jBESjKRSL5NHyPBpz3bE=; b=FbHz+yU7CdiKNJgHTHJZO+aGgDPJH05d/kbCP/MrJK3S4Ra9Q5+fHv8o5YPmSRRGg4 VM9sf0WAFeOL1WnYF8Byjee5HOXsaAp9BkSAwJ2MxtgzyDsqYolj7+0HeQvrysncf31g pvgG/YQISpUH/3NHpu+uHcQAYfNkllIoFaQa/r2sE2jXu2TgmZJ55Kr9TVcjInsiT4jQ gWVbSDynt8rkiT86h9Gt278U1JiunHSjug8GvgF4CG0uISutFvcEe2K9dxowoOd9zogv 7adEiDzPCo1pOWW6XgHHYefOpJBKcIDe28U1Z6LggC5ug21MRttRw67Iijg57llYq1Mh +zpQ== X-Gm-Message-State: AOAM533F/4T1N8JPFOpK/gH6UgyflXUNaX2mCcKhv8leZkaMb05IYj7E Y9x0NM6e2ruxb5xBmKl2nQo= X-Google-Smtp-Source: ABdhPJx8QBW8QFVwjDZADkajTlp0sdT5KxLzuXfAW5mMQG9nVWU0QE/iJo+TiJ/og54KjLJtRpsapw== X-Received: by 2002:a17:906:7e55:: with SMTP id z21mr496501ejr.154.1606150741074; Mon, 23 Nov 2020 08:59:01 -0800 (PST) Received: from kozik-lap (adsl-84-226-167-205.adslplus.ch. [84.226.167.205]) by smtp.googlemail.com with ESMTPSA id cn8sm5335926edb.18.2020.11.23.08.58.59 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 23 Nov 2020 08:59:00 -0800 (PST) Date: Mon, 23 Nov 2020 17:58:58 +0100 From: Krzysztof Kozlowski To: Alice Guo Cc: robh+dt@kernel.org, shawnguo@kernel.org, s.hauer@pengutronix.de, linux-imx@nxp.com, peng.fan@nxp.com, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH v5 4/4] soc: imx8m: change to use platform driver Message-ID: <20201123165858.GD214677@kozik-lap> References: <20201123095108.19724-1-alice.guo@nxp.com> <20201123095108.19724-4-alice.guo@nxp.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20201123095108.19724-4-alice.guo@nxp.com> Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org On Mon, Nov 23, 2020 at 05:51:08PM +0800, Alice Guo wrote: > Directly reading ocotp register depends on that bootloader enables ocotp > clk, which is not always effective, so change to use nvmem API. Using > nvmem API requires to support driver defer probe and thus change > soc-imx8m.c to use platform driver. > > The other reason is that directly reading ocotp register causes kexec > kernel hang because the 1st kernel running will disable unused clks > after kernel boots up, and then ocotp clk will be disabled even if > bootloader enables it. When kexec kernel, ocotp clk needs to be enabled > before reading ocotp registers, and nvmem API with platform driver > supported can accomplish this. > > Signed-off-by: Alice Guo > --- > Reviewed-by: Krzysztof Kozlowski Best regards, Krzysztof