From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.ozlabs.org (gandalf.ozlabs.org [150.107.74.76]) (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 B9766275870 for ; Fri, 13 Feb 2026 06:14:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=150.107.74.76 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770963277; cv=none; b=coDjBau0uS5CuzBz1UGKGQ7UwP1W7PWmLYvf8s9aQwPbj2KZ/Wnkmhy4E9S95ZLMEa8NcSTzPmGBLVCejhW80soa/tp7po274C17OlbNOdjEcs09Ifam3xiO7Lczj8JddDBGBy/fSzFICL1ggkxItjdgS57ZdRwWvncVSkd345s= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770963277; c=relaxed/simple; bh=spCy31IL8myHuBSyJSpd6fMfKjCTNBgbex3Y1uMDaqQ=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=r9MBscp8Feo2twXrgxatz9mx3lC1qGspeBPf5w260sOPvuTlcphUODpcH22tp5yLijSzfub0Pq38Ir9teHuPG0sS7gwfr8ts3kGl0NVMX/dcrwoF9ztYecdKpBYW0YdxuoRgc6BkBFf4GNzbjMi1HQ2cHejmZl7uiN+fFmuL/Po= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=gibson.dropbear.id.au; spf=pass smtp.mailfrom=gandalf.ozlabs.org; dkim=pass (2048-bit key) header.d=gibson.dropbear.id.au header.i=@gibson.dropbear.id.au header.b=MbCMSAQl; arc=none smtp.client-ip=150.107.74.76 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=gibson.dropbear.id.au Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gandalf.ozlabs.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gibson.dropbear.id.au header.i=@gibson.dropbear.id.au header.b="MbCMSAQl" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gibson.dropbear.id.au; s=202602; t=1770963267; bh=6lih/soOQLT0IASnOkxydfP8yu4mvx6Jlp2kt942dmw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=MbCMSAQlnv7VOtpfyLPsApF0pZGMNXWOZiG+1C1PsxYz9atVq83d+ohl8ypMHu7MN nEeadmxWKCVaFsIEWhv6hujQtsw8dQsy7/J2ZwYZQJaAtpJySuvU6HQIL7lu5lb8TV QhanciQFbApcO+OaRexYls3rqnriy6O1JPDZlz3A17K5eBvNjQRo3rdeDkXsFFgBoH jQRzsWRCA9lP7/Qhk9yUtWC0QHk5xHGG6iJe7v6o3dk4AOCOt3LtqmxY14rVP3Xy0I Yx8Uslp4y8sXp6ao5Tg0LCXxRXzQhCzZc2uJtoMFzD/mAv3VyACHpisLElgt83qcML Sfgszr/UCqWqg== Received: by gandalf.ozlabs.org (Postfix, from userid 1007) id 4fC21v5PfBz4vyg; Fri, 13 Feb 2026 17:14:27 +1100 (AEDT) Date: Fri, 13 Feb 2026 16:16:35 +1100 From: David Gibson To: Rob Herring Cc: Yao Zi , Kyle Bonnici , "devicetree-spec@vger.kernel.org" Subject: Re: Ranges - Intended use case Message-ID: References: <7CB259ED-7AFC-4EE1-A926-54A5F6DCD97B@hotmail.com> Precedence: bulk X-Mailing-List: devicetree-spec@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="IS8tP/3deCdLzXAg" Content-Disposition: inline In-Reply-To: --IS8tP/3deCdLzXAg Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, Feb 12, 2026 at 01:24:20PM -0600, Rob Herring wrote: > On Thu, Feb 12, 2026 at 9:33=E2=80=AFAM Yao Zi wrote: > > > > On Thu, Feb 12, 2026 at 01:14:33PM +0000, Kyle Bonnici wrote: > > > Hi > > > > > > I have been trying to understand how ranges should/should not be used. > > > > > > Looking at the spec > > > > > > > The ranges property provides a means of defining a mapping or trans= lation between the address space of the > > > bus (the child address space) and the address space of the bus node= =E2=80=99s parent (the parent address space). > > > > > > This to me the spec leave some space for interpretation on if ranges = should be used on just buses or not. Below are some examples to try to get = a better understanding. > > > > I'd like to say ranges literally specifies the translation process > > between the children address space and the parent one, regardless > > whether the parent is a "bus". >=20 > Yes. >=20 > To put it simply, "ranges" should be used whenever the child nodes > have memory-mapped CPU addresses. That's the most common case, but others exist. You can encode cases where a device's registers are mapped into its parent's bus address space, but that parent address space is never mapped into the CPU MMIO space. --=20 David Gibson (he or they) | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you, not the other way | around. http://www.ozlabs.org/~dgibson --IS8tP/3deCdLzXAg Content-Type: application/pgp-signature; name=signature.asc -----BEGIN PGP SIGNATURE----- iQIzBAEBCgAdFiEEO+dNsU4E3yXUXRK2zQJF27ox2GcFAmmOs6kACgkQzQJF27ox 2GdqihAAnm2SEblGkpXJG1QA38VeFTUusdoKJX4Or85aEkaqPDcO9YTSgkGBh8Fi 734+Z0DLWWUsddLmfR+sPB49UcxWtZLBJSYrcSoiytZLMsnOo76CV4l7G8x9yMV/ zsyeoiK6wdlBjhblyh+1IbIn7I4qzGN9EmaUOVHIyUTFk9Xzj/Jj0tVue1xcfMet Je2WXClIVsjxBsjNAoSzHEJkaUZ/lmmFg+oruvtRgTz5v52wMoS/XPU96qSpACJY 5f+vFn7KSeBqhvuhwoiSEUoV7cxfybCK8JfjoOtQoSviWChSK19Qi2LEdRamHMZT 0KO4/51UnwDG2XrDkO0yJ/qpDVr2p/wJBAGvYh8F2G0grfiNaCFNVpGnYPQtM1GC c7Zq349KH64IoyC/HCHTqASI/Unqqlf2USR6bacpQJB2fLjMfYJ0SxNGUPng/7ue 5uWKaIWq8XVCH1L6zSGBPRg9l6uzMA0eqa/FMgkwMs1DS8gxypDJ/R7IbSKISDmM 8+XeckfMEQ+8m8r7TJ0IDoieJKJOkN8D3H6ZauN9zDbgvPRHtHUVpsm/j8MKws4m mpws83PwCdvfxQ3yptdo7uNv6DNx/iDNaV8m2AfcAA2Oyp23jAlMgPKA3NfZMlHl chToAY48CnpVGm5jveHlqklU6JdGXdqu70e0Y1OlOVGuDzeU4v8= =fbky -----END PGP SIGNATURE----- --IS8tP/3deCdLzXAg--