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 3B7562F39C2; Thu, 13 Aug 2026 09:20:09 +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=1786612810; cv=none; b=byEJOnWy1GpzIiyU8euFSLAjxZx17mc4hVt3c6RVvShCp8O7hYS4h/Pfyu7WEnm+4Zsr359mLofttGi19AYNXotYyOrOEHPRCu5cNaAYNDQ4WOSFpfFNppt9xh9p9QJ88PtNW9oWVpgzWHMVPwjQxxdM6gQDVokWWQxaj6G4S1E= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786612810; c=relaxed/simple; bh=WD/K1Kwybt/UTK1xr9nUogPjHmDRSaMpQ7xP3IPbXzo=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=JYZFv1JrkaNLInFt7nRZVCTh8m1p6zgfsWt9RhgS4W8jUXfhdE7NYhqeD503F6F9cAJvolQ6flmnlyyPpwzrQ+MsJNaR19lFGJnRD9bmP2FnaijOXJoTh5AkNq2UvtnkgpT3SX+j352DN8q9+TqBoxHH1VUGQQLtdr0RxW9jfgQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=VXCzyror; 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="VXCzyror" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C1DBF1F000E9; Thu, 13 Aug 2026 09:20:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1786612809; bh=OHSkRs4KEkrny8lhy3H/h6oqzqJD/Yof8MZF9vXzETk=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=VXCzyrorL/HF4vkf5etfraIqCKEqrG5eDQA/tL2XvRHFG8rPZUu+xM2KO6AMx61Wv U0evXa1L0PY7akrWh5fwddRmOoQPGds2sx0JVCzZ2g/MZKiynbM/DCf5JKRBQr1JJY PejhchhDP75eFsWyfjg8RqLW99etO/1Kh2JzDhu56dlGETSjuITerG2S4LLuXPcB4+ HEcr2TYaasFohqW/TJX4ONyiOCs9KIxWPbk7VB0MoG0+/HDZedVKSFVRfhU8x5bRS4 UrwTMrhUN0YQ8kyKXz1JIrpk7HDnSvjj6fjck6b1v3nqGAlpOjMWuXKMNZ86gXTTkJ cxZXTREatdgeQ== Date: Thu, 13 Aug 2026 11:19:58 +0200 From: Krzysztof Kozlowski To: Vishnu Reddy Cc: Bryan O'Donoghue , Vikash Garodia , Dikshita Agarwal , Mauro Carvalho Chehab , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Stanimir Varbanov , Mansur Alisha Shaik , Bjorn Andersson , Konrad Dybcio , Abhinav Kumar , Hans Verkuil , Stefan Schmidt , Hans Verkuil , linux-media@vger.kernel.org, linux-arm-msm@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH 2/4] arm64: dts: qcom: sc7280: Add dma-coherent property into venus node Message-ID: <20260813-frisky-augmented-crow-fd5d3d@quoll> References: <20260801-iris-fixes-dma-pseq-fint-v1-0-aba0cb22f6ab@oss.qualcomm.com> <20260801-iris-fixes-dma-pseq-fint-v1-2-aba0cb22f6ab@oss.qualcomm.com> 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=utf-8 Content-Disposition: inline In-Reply-To: <20260801-iris-fixes-dma-pseq-fint-v1-2-aba0cb22f6ab@oss.qualcomm.com> On Sat, Aug 01, 2026 at 01:07:28PM +0530, Vishnu Reddy wrote: > While testing with some higher resolution clips, the venus hardware > triggers a fault due to wrong input data being received. Corruption > was also observed in the captured output when the client dumped it > to a file. > > On debugging, this was traced to the venus node not declaring > dma-coherent. As a result, DMA buffers shared between the CPU and the > venus video hardware/controller are not guaranteed to be I/O coherent: > CPU writes to an input buffer can remain in CPU caches without being > visible to the video hardware when it reads the same buffer, so the > hardware receives input data that does not match what the CPU wrote. > Likewise, on the capture path, data written by the video hardware to > the output buffer may not be visible to the CPU, so the client reads > stale or partial data, resulting in corruption. > > Add the dma-coherent property to the venus node so that DMA buffers > shared between the CPU and the video hardware and controller remain > coherent. > > Fixes: 37613aee2179 ("arm64: dts: qcom: sc7280: Add venus DT node") Really does not look like a fix. How skipping a cache sync can fix anything exactly? Best regards, Krzysztof