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 9F30B3C2BB0; Wed, 29 Jul 2026 10:11:03 +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=1785319864; cv=none; b=XCvu+nXn0aNyF4ba+pKzuv3Tz4K9SfgkBRLv9P1atlwGZh1wpq2QJhsGf+OP6JqQ8wG/XQYazUmMHwQ4zMHZlxmAFvfFxhVW0V1lXydBGV01+82lNBDkyaWkRFPht+fP9w5q8cH8hqNkMcQqw3XMX0m28gEiMONjLT9k6VxQTyc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785319864; c=relaxed/simple; bh=b2v+YaE6nv1aMga9k3xauOnYR6TA+lC9uby7PrsmzmE=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=AOvWGk0I6Jm72VpY75OAqgdGKj6Seqj+W37wsJAPNImY/tLAyAPABrffYxeQFk2N9KyjZq4l/94gVh/dugkw0zENUF2sa2xdejIyGjPi+c4E+TcQRK4J8k/FbUOATjsc94mI7tO48fG/V9uxSUYIE0aSHeLhEi2bb2JaHAmf0qI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=KlqVzRvk; 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="KlqVzRvk" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6012A1F000E9; Wed, 29 Jul 2026 10:10:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1785319863; bh=gpEM1giuOjXURuyUiQ5sHXw2Jpg9fbLoQpv9NJUkXeo=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=KlqVzRvkTOLiJ3dD93dPJwP/029QEgKGt8TaLcutoa6xPb1OMMTPg54ctSHRzXFlW j71F4UIGJiqzw7nKPql9JPiBuHK/2OcgFaGpMbLZGjej0Pt5exaLes7ZqugymWTwNk hI7d7aNofik82JKvBDeGUHFrEj+s97d/UPjsrcs8JAkP5QO9aTb33wCdj5UzbM+WNc WIaW12IfuYH4dLTSkjpNaFh4Xg+MHbLhxmBoXSJFCodBqPkkcAh4+o4mIfaRJWPNlH ZE1p1sm7QJDFLkJOT6ckN94Sr67zvnHrs/Eg0r/EIpAHJ7AfRvocovmyV2iCh0xYHX qJddT1r6D9BoQ== Message-ID: <2b0ea2a2-c3ef-4147-801b-af41733fba7b@kernel.org> Date: Wed, 29 Jul 2026 12:10:53 +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: [RFC PATCH 07/11] arm64: dts: qcom: hamoa: Move Iris IOMMUs to sub nodes To: Vikash Garodia , Dmitry Baryshkov , Bryan O'Donoghue Cc: Dikshita Agarwal , Abhinav Kumar , Mauro Carvalho Chehab , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Bjorn Andersson , Konrad Dybcio , linux-media@vger.kernel.org, linux-arm-msm@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, Vishnu Reddy References: <20260709-vpu_iommu_iova_handling-v1-0-72bb62cb2dfd@oss.qualcomm.com> <63t_fLehIKEom4-JPN9kAGFEjUG4_yFoHMhB2aEAppwPHb2oPbK666eGkGgXxEAHRJnfTRRUwuf2EqNRYe_gjA==@protonmail.internalid> <20260709-vpu_iommu_iova_handling-v1-7-72bb62cb2dfd@oss.qualcomm.com> <5c8af0d5-2477-48ca-bd7c-0f2475a9dd62@kernel.org> <00df448b-b492-4c85-bba9-84753825c265@oss.qualcomm.com> <3128bff0-98a6-44d7-a390-27537e74e9fc@oss.qualcomm.com> From: Krzysztof Kozlowski Content-Language: en-US Autocrypt: addr=krzk@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 8bit On 16/07/2026 11:07, Vikash Garodia wrote: > Hi Krzysztof, > > On 7/13/2026 11:32 AM, Vikash Garodia wrote: >> >> On 7/12/2026 5:49 PM, Dmitry Baryshkov wrote: >>> On Fri, Jul 10, 2026 at 11:46:58PM +0100, Bryan O'Donoghue wrote: >>>> On 09/07/2026 13:35, Vikash Garodia wrote: >>>>> The Iris VPU has separate streams with different IOVA constraints. The >>>>> non-pixel stream must be limited to the 0-600 MB IOVA range, while the >>>>> pixel stream can use the full IOVA space. >>>> >>>> >>>>> Using a single set of IOMMU entries for the Iris node does not describe >>>>> these per-stream limits and can allow accesses outside the supported >>>>> range, which may lead to device crashes. One such issue was reported >>>>> at: >>>>> https://gitlab.freedesktop.org/drm/msm/-/work_items/100 >>>>> >>>>> Add non-pixel and pixel child nodes, move each stream ID to its >>>>> corresponding child node, and add a reserved IOVA range for the >>>>> non-pixel stream. >>>>> >>>>> Co-developed-by: Vishnu Reddy >>>>> Signed-off-by: Vishnu Reddy >>>>> Signed-off-by: Vikash Garodia >>>> The thing of it is, this _is_ a bugfix - perhaps its not one that can be >>>> backported, actually scratch that, this isn't possible to land in - >>>> stable >>>> realistically. >>>> >>>> So what is needed here is a strategy for fixing -stable. >>> >>> I think, we need to start with defining, which platforms are affected. >>> sm8150+? SM8250+? SDM845+? MSM8996+? >> >> All platforms, including venus. >> >>> >>>> >>>> That could be apply Daniel's patch and backport it with Fixes: - with >>>> mainline then say applying this change and reverting Daniel's patch >>>> >>>> or >>>> >>>> That could mean some other solution for -stable - up for debate - >>>> what's not >>>> up for debate is this series needs to _address_ what happens to >>>> stable for >>>> all of the target platforms - and then transition mainline to the new >>>> and >>>> shiny way. >>>> >>>> That could mean >>>> >>>> - Applying Daniel's fix with Fixes: and cc-stable >>>> - That patch needs to be extended to _each_ Iris platform containing >>>>    this bug... all of them I think. >>>> - Updating bindings >>>> - Updating DT with new method simultaneously reverting Daniel's fix >>>> >> >> Ack. The proposal seems a good way to me addressing stable, i can work >> towards this. >> >> Will wait for couple of days if there are any alternate suggestion on this. >> > > I would like to seek you suggestion on handling for the -stable branch. > The approach proposed here is; > > 1. Pick the workaround from Daniel, and mark it as Fixes: and cc-stable. > I have the series ready to post considering for all _iris_ platforms. > > 2. Update the bindings with subnode, and at the same time, *reverting* > Daniel's fix on mainline. > > This is due to the fact that #2 might not be easy to apply to all stable > branches, #1 would serve as workaround to fix the bug in --stable trees. > > Please suggest if this is fine with you or any other way you would like > me to pursue. Sorry guys, but the logic here is not correct. We do not develop mainline kernel in a way that satisfies backports. IOW, we do not organize the commit history in any other way than the mainline development purpose. Whatever you try to do, add some semi-correct fixes, then revert them so backport will work, all this is just wrong. There is NO DISCUSSION about stable here at all. None. Best regards, Krzysztof