From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wm1-f48.google.com (mail-wm1-f48.google.com [209.85.128.48]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3EE8A3563F3 for ; Wed, 29 Oct 2025 18:47:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.48 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761763670; cv=none; b=axYV/MDRTpJVYItvjYLNl7XmGUUiMMuzVHLk+x/adozWITOnPwBOmBKX5o45p6rF3o2vnusCU/tAjFmQb5CGKo/ZcqcLZ1H90OQLK39FKfKn7hyiSkJgqWYlXSPAvaA27tD6c/t70sOL2SqvEZs9PsqxnpZS/Clcbl2tMJSqOKg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761763670; c=relaxed/simple; bh=0Tr3LCSHb84ftOumUd9propiyWY/G1DK/xvBH3c4z0k=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=H4c4VhGIG7wFxo9Anj5BVXQsG8B5JXTuZm8rkhEPymI1eCh0zOHgnJUlQLG9Caks2WqxgUdHNr3yTe0DNI94+cSOHPUbuFbAkIwHGaQaOeTtdhkoDHX0aMH9n1nuoI54oh0WTLMgfW/qD3ZRnLHSklAqKq34UaCi0G3vxCmOD+g= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linaro.org; spf=pass smtp.mailfrom=linaro.org; dkim=pass (2048-bit key) header.d=linaro.org header.i=@linaro.org header.b=hZSaB6st; arc=none smtp.client-ip=209.85.128.48 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linaro.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linaro.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linaro.org header.i=@linaro.org header.b="hZSaB6st" Received: by mail-wm1-f48.google.com with SMTP id 5b1f17b1804b1-47719ad0c7dso1802865e9.0 for ; Wed, 29 Oct 2025 11:47:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; t=1761763666; x=1762368466; darn=vger.kernel.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=n7UlL3GKzUDEprO6nc/X4PQZdsoNuJnhVXYl9pMuUgU=; b=hZSaB6stfLACJmEqNsUdwjSf2xtOI5p6B3TGS/c5ftCfg7bSAZ6/pTAloV+Cwgxl/t Bh2YMigTgCP3OfdV31YYEMKAdOoKj5hgVHMv/pMpFtJ6as6GdbSu8R27zJoLBI5S7fOn xn9UWzWrK1orsjyrfi+0oo3e4MhBxvQ7znYr7cdFedmj+rF27Y4USBbK2t+M7iJhxg6C EKIQCWOsxGvLOIY1urX8aAOEQCdqq0mqYGLnCj6KFUmOBML8/nftx5THwq2utv+lqbiS PeLeRNI24xFY5zFec19VrJEUSLqbLyzbMJND7suffct6Ll1SbcwiAJjtBtNdEaWevh/q 9hOg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1761763666; x=1762368466; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=n7UlL3GKzUDEprO6nc/X4PQZdsoNuJnhVXYl9pMuUgU=; b=dpsmESjK+5IfH/63VgrNOtaJAdlvwSpyyIbb9uMfxYbYLIZRuy6ZghLAP8jbwMIMdE DJWWmKtrRL5Jdn+XTg4cVnOvlLqaESC32ixgaLaWddRlfel8a4tF4oa0q0OQOQbuSg09 S2jccOYFhdKjUw2dP571wIYg4hc9DodFbDBrEqKC3QySvjiv+sj9S8KfW1K+TeYquWAM SkbNEJ03GYGwd4IsIhFsaJcBXEpsWb9N4Pwcs9qOpa+fuJa8wq4ZfOS/3bYCjVqr/JXa jT2fFDoB9I5r+aVhZEXjUS24CDNAb2F0GfwePwH1ZZJD2wonm3kU4HDzV0p8A9M8yn/d Jp4A== X-Forwarded-Encrypted: i=1; AJvYcCUOSRiGuTFD8uaAyA9B/litVWqZl+JBiVwXH2Y9E/ci7ADOwyOI0DkIBUCXAb89oncePAtRc9Tc967yyPY=@vger.kernel.org X-Gm-Message-State: AOJu0Yx29OwlVlb/GhJ+MnAbr1KOKln7EW+xuPte6NAT7CIIh49/HlU0 T7FmgxBhA0AUTHZWoz/fKWlxegPZ+zwBT1fYayeCVYV6l4NN+LIxIw6T1nExwY2A704= X-Gm-Gg: ASbGncsokUTLSgYQ9/rwwD6UirsE7jLqU8P/0cQUCzdRjjL64yR6H6g3hEeQo7Yn9yQ wFOBZEC3fyAqjMG82U/IhvbSMpfCHqbFOrcDeOUmQm2TQmEMRauTbFF6fAKK6dZjlQftYR5yuef XI4pTleafKlgETd5z6ul9Yxws9lwjS/U+qFVwKjj9G/tlg6axnNT2PLmgLwb3Lzb10gEDhg/7ru OUUmdv/cQMpgm6/KMALXhupE3zAHMNcNVVa/uCxhILvpxahqfZ7UneBkRo+UM4b+8fD+AAWCE2t I0GTxcaE8Xn1bAxM8H3ypKqPMhzQg42dKV7YXJIqc1ASWdrKSJyrxWoCGKrKouUuSL9oy0RJvUa PeLF+/RLeQTIDLPwFjQnwjQEA41Ppzjwlt4+PsUdS7jZkedd03vWrF82ZxDdjBfeMCE3PPyubpC rVAhlWbVlpea1dtk0+ X-Google-Smtp-Source: AGHT+IGpoPX9hNhKmRBMmW2j12M72FSxxCuC4T9cB82GM76vjMbsT/vObteBlRgx4MZwjCJgYtHIEw== X-Received: by 2002:a05:6000:26c3:b0:427:45f:ee1a with SMTP id ffacd0b85a97d-429b4c8748cmr573409f8f.25.1761763666459; Wed, 29 Oct 2025 11:47:46 -0700 (PDT) Received: from localhost ([196.207.164.177]) by smtp.gmail.com with UTF8SMTPSA id ffacd0b85a97d-429952d5773sm29704529f8f.27.2025.10.29.11.47.45 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 29 Oct 2025 11:47:45 -0700 (PDT) Date: Wed, 29 Oct 2025 21:47:41 +0300 From: Dan Carpenter To: Conor Dooley Cc: Lee Jones , Rob Herring , Krzysztof Kozlowski , Conor Dooley , devicetree@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/2] dt-bindings: mfd: syscon: introduce no-auto-mmio property for syscons Message-ID: References: <230cf12861a4f0b9effc72522444d3e28c1de2c9.1761753288.git.dan.carpenter@linaro.org> <20251029-ambiance-snooper-43dc00dcee68@spud> <20251029-embroider-plunging-6356f50c7acd@spud> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20251029-embroider-plunging-6356f50c7acd@spud> On Wed, Oct 29, 2025 at 06:37:26PM +0000, Conor Dooley wrote: > On Wed, Oct 29, 2025 at 08:41:51PM +0300, Dan Carpenter wrote: > > On Wed, Oct 29, 2025 at 05:33:48PM +0000, Conor Dooley wrote: > > > On Wed, Oct 29, 2025 at 08:27:05PM +0300, Dan Carpenter wrote: > > > > Generally, syscons are created automatically and accessed direclty via > > > > MMIO however sometimes syscons might only be accessible from the secure > > > > partition or through SCMI etc. Introduce the no-auto-mmio property to > > > > tell the operating system that the syscon needs to be handled manually. > > > > > > "System controller node represents a register region containing a set > > > of miscellaneous registers." > > > > > > If this isn't actually a register region, but is instead an interface > > > provided by SCMI or whatever "secure partition" is (optee?), why is the > > > syscon compatible being used for the device in the first place? > > > > In the case that I'm looking at, it really is a syscon. So right now > > we're upstreaming it and it's an MMIO syscon. Very straight forward. > > But later, I guess, they want to have a new firmware which will only let > > you access the same registers through SCMI. > > When the programming model changes, the compatible should too, no? > I wasn't planning on it. I haven't been asked to upstream the SCMI module but once my thinking was the transition would work like this. Step 1: It would work as is with an MMIO syscon. Step 2: We would upstream the SCMI driver which would provide an MMIO syscon as a fallback. At that stage you would still get an MMIO yscon regardless of whether the phandle was parsed before or after the driver loaded. Step 3: We would set the no-auto-mmio property so you have to use the driver and update the firmware so only the SCMI interface can be used. regards, dan carpenter