From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 E787C431A2B; Thu, 6 Aug 2026 09:20:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786008021; cv=none; b=KdHgYsavuMcRzx99ZHigzhEeogDa+Ujxh/IXCMOEgRn7YeEYOgbhbcZGRdnLb8cDADP4GD1UKLjM30KrkXSWJIZb3bMTNoxK4atdNyGW6Ph/YO1x1UcUuiCHrV6DQACK1rk6rfG5SL2yQgBZo4a9RP5u7wP5DJxDINgOnv2wheo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786008021; c=relaxed/simple; bh=jud4DCF3dznJD9IVUp/NPwI1SiYzOcqCdgmq3NM7IpM=; h=Message-ID:Date:MIME-Version:Subject:From:To:Cc:References: In-Reply-To:Content-Type; b=eFT68enxj/9c3JgqFGGRiU8pr4J0ouI/3gSXZSCPMeSnfhkR4Dx3E1j5PD5ynHrrK6AhuG+6ncnMlhv6vbaRCM3jlCWk58A1hXortdBhmtvXfPHU4aQOsQsRVAzYp6HObD+flqD1PNIpWnB1HLSm0bSAzNJ0wXSDX/cj0YUJ4tU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=g/lejn03; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="g/lejn03" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4D7A71F000E9; Thu, 6 Aug 2026 09:20:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1786008019; bh=iGxek032oK2fSaxH+Kzf0mPcVIk2FAv6elrIDa8hzJ0=; h=Date:Subject:From:To:Cc:References:In-Reply-To; b=g/lejn03Ul/ylviBdhxYK8cnWQtzz78zo8Nb6v3Pfjb5QLxpcqgPJQsIElpQOxWVH rmrJGB/y1U+67692/RhvrBa3QeEgMCEYxwtm0CazkypyQiCLbV46BeSi1pU3hDS6Nu qqoN6IG6kvtbQT37DfVBJbbYgDJ8WbhWq51zeDuY+2ELq1MYXnSTbmHILiST+uSBW1 /XKlqDIyaTGBoefRm7B7Gf7ifgh0kvkZfeIlWQUF9W9HDMl4QXWm6/6QsC+91YmjOI VrcDigJxD2q6YXwHvt8sfp3ANwDfKfSSjiRs86xueZOkN5iMYYupwJyMxE9aicTPKO 9ylG3IlEfiRuA== Message-ID: <0f6c0803-1f87-4c2f-97c9-89b0546a95b3@kernel.org> Date: Thu, 6 Aug 2026 11:20:09 +0200 Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 01/12] dt-bindings: media: qcom,venus: Add context bank subnodes to common schema From: Krzysztof Kozlowski To: Dmitry Baryshkov Cc: Vikash Garodia , Dikshita Agarwal , Abhinav Kumar , Bryan O'Donoghue , Mauro Carvalho Chehab , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Bjorn Andersson , Konrad Dybcio , Stanimir Varbanov , Neil Armstrong , Bryan O'Donoghue , Stephan Gerhold , linux-media@vger.kernel.org, linux-arm-msm@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, Konrad Dybcio , stable@vger.kernel.org, Daniel J Blueman References: <20260731-vpu_iommu_iova_handling-v2-0-da52b5228dbd@oss.qualcomm.com> <20260731-vpu_iommu_iova_handling-v2-1-da52b5228dbd@oss.qualcomm.com> <20260805-dark-voracious-jacamar-6aae4c@quoll> <7a546bc6-a2b4-457d-ac27-05fc1cfe17f5@kernel.org> <163c24ba-6b78-44bb-afe9-3dcbb4d47475@kernel.org> Content-Language: en-US Autocrypt: addr=krzk@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 06/08/2026 11:11, Krzysztof Kozlowski wrote: > On 06/08/2026 10:46, Dmitry Baryshkov wrote: >> >>> dma-ranges tell how this bus - so venus/iris - performs DMA translation >>> in respective to parent. Address/size-cells are obviously also needed if >>> this is a bus with addressing. >>> >>> But there are no children with addressing, thus what sort of bus would >>> it be? >>> >>> It looks to me that having here both: >>> 1. dma-ranges + address/size-cells >>> 2. children without bus addressing >>> is some sort of abuse of the DT syntax. It is allowed, but does not >>> really represent hardware. >>> >>> IOW, dma-ranges alone feels okay, although unusual, and it states proper >>> DMA translation for this bus. If you add address/size-cells, it means >>> this bus HAS addressing and thus YOU MUST use addressing. >>> >>> If my understanding is correct, then solution would be to add addressing >>> to the children (so unit address and "reg" property) or drop >>> address/size-cells as Rob pointed out. [1] >> >> Doesn't dma-ranges require address/size cells? In the end, how can you > > I think it does not require, at least how I understood the DT spec, 'dtc' disagrees with me on this matter and treats 'dma-ranges' exactly the same as 'ranges' property, thus requires address/size cells. So maybe my below interpretation is not right and the schema is fine... Rob commented earlier on a case which had address/size-cells but no dma-ranges. https://lore.kernel.org/all/20260716165434.GA290489-robh@kernel.org/ > unless you provide actual addresses to the property. > > IOW, this requires address/size-cells: > dma-ranges = <0 0 0 0 0x10 0>; > >> specify the DMA address if the device doesn't have addressing at all (or >> MMIO-style addressing)? > > Yeah, that's why having here children without bus addressing is > confusing. I would interpret it that, children are not on MMIO bus, thus > the venus/iris is some sort of proprietary bus with no mapping between > parent MMIO and children nodes. > > If there is no mapping, then we do not have 'ranges' property. But I > could imagine that such no-mapping bus still provides access to system RAM? > > Actually this feels like a huge stretch, so I tend to think that the > only reasonable option is to have children with MMIO, which would make > it explicit: Venus/iris is a bus which provides translation of both MMIO > and DMA addresses to the parent. Best regards, Krzysztof