From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 60BE68479; Thu, 11 Jul 2024 15:51:21 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720713081; cv=none; b=mKZZShUB41uMTVpAlgNHHpmzMbkEil7R1P8R9wZHpYMpYLPWdfyWH39AAY5LYdTKtoZPZSrhApLPjnn9AIgVWVQB5KESC9W2xtBQD50Argos6XhMr+EWyjlfo80LyljnjYD9XDQbPFNiEOAZXR78Z8un/Ch6stXM+1bkUxg5XDI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720713081; c=relaxed/simple; bh=Kdn4yBHek2NTiF7hAs11T2gTBUI2nFR7JGBd9fLx2MY=; h=MIME-Version:References:In-Reply-To:From:Date:Message-ID:Subject: To:Cc:Content-Type; b=nc8js9N49Kdu4oqKXJMTQ9UxocYOlDBp7LBXd/Mytck6gH3R2P4C1xb5tX/2lXZ4r2qorc+0QsmvDVe9t6tgY8IJgXTpysHzjQ98L3ms01cRyQ3SG/Jim7W6tByH9+a7WER9EGMoUmazpHtqmDg2zpUjumhmZO7x1kfTYb8nRqk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=UfBp3l6R; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="UfBp3l6R" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3F93EC4AF0B; Thu, 11 Jul 2024 15:51:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1720713081; bh=Kdn4yBHek2NTiF7hAs11T2gTBUI2nFR7JGBd9fLx2MY=; h=References:In-Reply-To:From:Date:Subject:To:Cc:From; b=UfBp3l6R84Er64lHrZ1+8IF9Xw6KD1q9Q82537YVxCbY0JmVUAWe/9DYpjS/XjLa0 WIQ32JUL7Jdj2/DxWMIgU2gHGLOYhhuET58fy/87CX7nAPM/98lyJ3oAE36dFW8jh1 Z/LYm8V5mOLF9vhtGRuKaGDDy+VZvQwJq7KwYcNn94BjCV4yVgzmyWya8WORlibYsq c3vyO0eBulE1WXIxJWR3zEJpK0Dm0/L7lYfO0pgvbQTjAhTOzg1TSemTkf3PCE9BM+ V7ZFlgcyL8Cp38U8UAi1lLbQuKl1kM0XzbT9i/hYm89MeHxrQVFmHyBTBOswitS37s b4cVPtT2FiWZg== Received: by mail-lf1-f41.google.com with SMTP id 2adb3069b0e04-52e97e5a84bso1513114e87.2; Thu, 11 Jul 2024 08:51:21 -0700 (PDT) X-Forwarded-Encrypted: i=1; AJvYcCUvg40gpMuu69toi5iXnKTThfGwz/sOw1yIZxQokh6x5WuBnsmKPhuFhzd8ZQ3tMHtftKixzmeuDsr1k1aYn+iGxlWRc3l31CIw3sy2npSCOgkXTkh0aHBXMIepZI4jpLYWkFFgLJmsFhDvLxHnOBB3MryHADOUbz/bNjhXMmZ8irYSvz1bRMotIG+Q1548HRhvnSi/jguDUcLxtrcGzagE2EG5UwKzZYEEBKDo4BBX9U6MqmyenqkOnvgyEfa+cmyLNTio X-Gm-Message-State: AOJu0YxpK3edfNUKQ25ziARP2xbXR8ySaXF5Xv8n/gnRjnhmg56TyKYI D/5uM1eJF6DFonsLa26om+O9odnsdWhc2Ge1yfUfHwUfjZmHetNTf+ytss34zcbc4GadrhKgL0n 5pXhj15WhHz/FjsI0FrXiEwraMg== X-Google-Smtp-Source: AGHT+IElxwI3DTbhcXoQnMJVlvwdauqS5RzGBQrc6N5zhGBYTcZbAbeLzaogiu4kSAPR8XV9dXyCGWkOpYxcz6H0KgM= X-Received: by 2002:a05:6512:b18:b0:52c:dd25:9ac6 with SMTP id 2adb3069b0e04-52eb99a3439mr7754037e87.29.1720713079582; Thu, 11 Jul 2024 08:51:19 -0700 (PDT) Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 References: <20240710-gs101-non-essential-clocks-2-v3-0-5dcb8d040d1c@linaro.org> <20240710-gs101-non-essential-clocks-2-v3-1-5dcb8d040d1c@linaro.org> In-Reply-To: <20240710-gs101-non-essential-clocks-2-v3-1-5dcb8d040d1c@linaro.org> From: Rob Herring Date: Thu, 11 Jul 2024 09:51:06 -0600 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v3 1/2] dt-bindings: serial: samsung: fix maxItems for gs101 & document earlycon requirements To: =?UTF-8?Q?Andr=C3=A9_Draszik?= Cc: Greg Kroah-Hartman , Jiri Slaby , Krzysztof Kozlowski , Conor Dooley , Peter Griffin , Sylwester Nawrocki , Chanwoo Choi , Alim Akhtar , Michael Turquette , Stephen Boyd , Sam Protsenko , Tudor Ambarus , Will McVicker , kernel-team@android.com, linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org, devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-samsung-soc@vger.kernel.org, linux-clk@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Wed, Jul 10, 2024 at 7:29=E2=80=AFAM Andr=C3=A9 Draszik wrote: > > While gs101 needs exactly two clocks for the UART, the schema doesn't > currently limit the maximum number to this and instead the default of > five from this schema is applied. > > Update the schema accordingly. > > Also, as pointed out in [1] before, the hand-over between earlycon and > serial console is fragile due to clocking issues, at least on Google > Tensor gs101. Therefore, document the clocking requirements for > earlycon in the description for posterity, so the information is not > lost. > > Link: https://lore.kernel.org/all/d45de3b2bb6b48653842cf1f74e58889ed6783a= e.camel@linaro.org/ [1] > Signed-off-by: Andr=C3=A9 Draszik > --- > Documentation/devicetree/bindings/serial/samsung_uart.yaml | 14 ++++++++= ++++++ > 1 file changed, 14 insertions(+) > > diff --git a/Documentation/devicetree/bindings/serial/samsung_uart.yaml b= /Documentation/devicetree/bindings/serial/samsung_uart.yaml > index 0f0131026911..2435c3d92158 100644 > --- a/Documentation/devicetree/bindings/serial/samsung_uart.yaml > +++ b/Documentation/devicetree/bindings/serial/samsung_uart.yaml > @@ -145,6 +145,20 @@ allOf: > - samsung,uart-fifosize > properties: > reg-io-width: false blank line between properties > + clocks: > + description: | > + Note that for earlycon to work, the respective ipclk and pcl= k need > + to be running! The bootloader normally leaves them enabled, = but the > + serial driver will start handling those clocks before the co= nsole > + driver takes over from earlycon, breaking earlycon. If early= con is > + required, please revert the patch "clk: samsung: gs101: don'= t mark > + non-essential (UART) clocks critical" locally first to mark = them > + CLK_IS_CRITICAL and avoid this problem. That's a whole bunch of details that are Linux specific which have little to do with the binding. > + maxItems: 2 > + clock-names: > + items: > + - const: uart > + - const: clk_uart_baud0 Which clock is pclk and ipclk? 'baud' would be sufficient for the name. 'clk_' and 'uart' are redundant because it's all clocks and they are all for the uart. Rob