From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx0b-0031df01.pphosted.com (mx0b-0031df01.pphosted.com [205.220.180.131]) (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 614A53AE1A3 for ; Fri, 14 Aug 2026 09:50:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=205.220.180.131 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786701005; cv=none; b=QFR//DJkht5wn9Zt3TQOcd02YmMoIuQDti2teyzJCcXHiyAscYQ1/FUGAGBlISdkgVxl/a2gnoB9XQbjWOhJhj4+LGxJR3tyhqSPOklpK+DfvtKU1CxnwBrDTYmjuOeGVh7aaiiRMrm0SkevUxTgMMS6HgXGCLr/PEnYXMpyQ8w= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786701005; c=relaxed/simple; bh=bbuQsLL8tNbhWQV7ZzutwSkYT7CQTJBHS2BgGEjkN+c=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=gDyfgWf+aFNO4IUmKSTbWIe6x42epES/7dxD+39weEzWUQm5AatxQSXJbC1cXEysaVw5sdJvgcar8sNeyow0aQftVRfuHorVLjVSUCAM4wyWXGFZrafF6ThnHsnsG486EtAdTdlU8iir61ZiZIxeX77k5TQ1zb9FL6voa27M/wE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=oss.qualcomm.com; spf=pass smtp.mailfrom=oss.qualcomm.com; dkim=pass (2048-bit key) header.d=qualcomm.com header.i=@qualcomm.com header.b=XOBIQGjm; dkim=pass (2048-bit key) header.d=oss.qualcomm.com header.i=@oss.qualcomm.com header.b=F6FTqVic; arc=none smtp.client-ip=205.220.180.131 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=oss.qualcomm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=oss.qualcomm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=qualcomm.com header.i=@qualcomm.com header.b="XOBIQGjm"; dkim=pass (2048-bit key) header.d=oss.qualcomm.com header.i=@oss.qualcomm.com header.b="F6FTqVic" Received: from pps.filterd (m0279873.ppops.net [127.0.0.1]) by mx0a-0031df01.pphosted.com (8.18.1.11/8.18.1.11) with ESMTP id 67E9BmUG1224258 for ; Fri, 14 Aug 2026 09:50:01 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=qualcomm.com; h= cc:content-transfer-encoding:content-type:date:from:in-reply-to :message-id:mime-version:references:subject:to; s=qcppdkim1; bh= bbuQsLL8tNbhWQV7ZzutwSkYT7CQTJBHS2BgGEjkN+c=; b=XOBIQGjm4V9isW3l VDkpseqsgGD2+cB+YnNpYmbW4TQ4ODlfHtk2vfDuHPycgr4Aezv76Y1fKN38bIZF UywzS4RnJ3A5RTScghTyCICdQIB3zGEmDTpmAWrACd+L/PSDL+SBQd55RE+B/5oO OVZVwU78ddrE3UL57ZfftmCFRMjbxkCDGST2CDz8g+N5WH6CdnQhNNTPZb2rZPY+ 7OafYnNF4Q92gavDv8Kl3dZVTZyFpslWSC7Xbvgd5WFo7qHluhk8n7Ln9qv0HgAP yrIkTYqsFC3ThGZeKsjMPJ/5AxIrtlWEcsVHNHNmqXv5t2hWaqNiSPjxlTor/ZTA EHaY/g== Received: from mail-pg1-f197.google.com (mail-pg1-f197.google.com [209.85.215.197]) by mx0a-0031df01.pphosted.com (PPS) with ESMTPS id 4g206384p1-1 (version=TLSv1.3 cipher=TLS_AES_128_GCM_SHA256 bits=128 verify=NOT) for ; Fri, 14 Aug 2026 09:50:00 +0000 (GMT) Received: by mail-pg1-f197.google.com with SMTP id 41be03b00d2f7-cbb92868263so529434a12.2 for ; Fri, 14 Aug 2026 02:50:00 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oss.qualcomm.com; s=google; t=1786701000; x=1787305800; darn=vger.kernel.org; h=content-transfer-encoding:content-type:in-reply-to:from:references :cc:to:content-language:subject:user-agent:mime-version:date :message-id:from:to:cc:subject:date:message-id:reply-to:content-type; bh=bbuQsLL8tNbhWQV7ZzutwSkYT7CQTJBHS2BgGEjkN+c=; b=F6FTqVicCAheKUYaH4Iwd7IU8nlJ4eRS9TL53o/y/BqDtmJmEvFUyhLl1S5NnOvfcG NEnf464IBWciP1Gigs/bb79NwVlSViAoYMiJM0GxRPpWKY2N/oaazb9VttgXfftwa6rF f+EGV9vAKAemWvwIi1SE4tbfa300qu4T8as1ojfHMr+JHLkHVUehncUDkRfG7rG5wgEp vap1whjgLcqFiStecZiL15JilMiMJf6Gl/PqbLkCa8/nsPpOnn3tmUSvwLcDosqajEFf ou1HIPfhZSVbStGzRFkUbBbvaQbzdKRn5i7zZegThbA/rVMRtBbiqMVzgUjstHb9yVkW xp6g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1786701000; x=1787305800; h=content-transfer-encoding:content-type:in-reply-to:from:references :cc:to:content-language:subject:user-agent:mime-version:date :message-id:x-gm-gg:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to:content-type; bh=bbuQsLL8tNbhWQV7ZzutwSkYT7CQTJBHS2BgGEjkN+c=; b=rf1jkRS6u0aQVVPpcEXFFeaUjsFSAIxIE8ATJ1I+tllUR6HSTATxg5PykBzcpf4efM xAQ353nUXOd2J7vA6wyGI5ERMmVPi0fBgHKGOEljM+rq/O49xfVdiTPmHZrDu5hq8NBW Xa7VISniVddxsLENivXohG8ZSk1SrloSUG2yWjOm9g9IIfSwEylBl8VzGorON2hu8bSY JQMzg8Bc06qMWsXPwh8ENrStIMLJxDUgQ5KWPXSFE+ptDq9MN3kIH5DRauFZpzQoYLrY Gtmz/TphsP88j/cmtxUCN6++RupyBllNjnPpFPBtTfFU8gWqxjQ1wtfNrCssOv6omnN7 U6aw== X-Forwarded-Encrypted: i=1; AHgh+RouCBrs6ippKbhGKdTsImqhyY7ifp2uDH81QhGeURjdGk0MJEq/JpCw5ljUzMtrf7HCIgVzyZPQmsSFjw==@vger.kernel.org X-Gm-Message-State: AOJu0YyZj4z072qqtH4iZhViIOmQYK4xFv13pWnRXaF319VfVTxOZDLL wCMDmsBV7J3o+rezdYnmtpI4gPJEBD0TG4vEpqALleoWaZKFB45seDZ2tEmoe3iwnKH1/G8Uqka XkKuR1rnY8BtKvVD6aO85ZFgZicFx4p3q1c9BQzx5Glzp5Hxp7QV5B4N/VQITq1FxBA== X-Gm-Gg: AR+sD12YrR0BbkhkYGMd69bB8fnJTKpkUPu1XtdrqrNDkm7UoXk3h8Q0M0/YDeu43fk 9a/TSR9jIA/4OhcWG0tiYbzNgi8lzBWliuYLT+wxA0AgY1d48L+H0bbvRGGmlCFIoqtjS1kxisu pLASPhVC73wll4DZLOm24awHI0HsS7mcALE92NJ9uutED1NoikURJsSbgqVFZMOgA+XV1SL+F/5 /16mLpYdG3Gf1e2Y1mS6FTDZNH1CbLKix+3223fxYaq3UvkaK7WtcgN5VH3z+oXHUtFnYuxfGtt cIqCyQoFvOsh+Xg/w3+YWYatvvxYnG9+bTJwMoeYNGL0A/PaBogujv2Md7RcqBa4ChHmWBi7uwF kJN9TwRQ4zwjqLldz9xDZpE37st33knvG X-Received: by 2002:a05:6a20:9f93:b0:3bd:3800:7538 with SMTP id adf61e73a8af0-3cc71de3f87mr4852492637.33.1786701000059; Fri, 14 Aug 2026 02:50:00 -0700 (PDT) X-Received: by 2002:a05:6a20:9f93:b0:3bd:3800:7538 with SMTP id adf61e73a8af0-3cc71de3f87mr4852449637.33.1786700999644; Fri, 14 Aug 2026 02:49:59 -0700 (PDT) Received: from [10.206.101.140] ([202.46.23.25]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-320d5bd9fd3sm2621667eec.4.2026.08.14.02.49.53 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 14 Aug 2026 02:49:59 -0700 (PDT) Message-ID: Date: Fri, 14 Aug 2026 15:19:51 +0530 Precedence: bulk X-Mailing-List: linux-media@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.8.0 Subject: Re: [PATCH 2/4] arm64: dts: qcom: sc7280: Add dma-coherent property into venus node Content-Language: en-US To: Krzysztof Kozlowski 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 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> <20260813-frisky-augmented-crow-fd5d3d@quoll> <4b34e718-0878-25cc-a5bd-0d8858df5133@oss.qualcomm.com> <30195e14-0dcb-476d-af0d-f85ee57e2aa5@kernel.org> From: Vishnu Reddy In-Reply-To: <30195e14-0dcb-476d-af0d-f85ee57e2aa5@kernel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Proofpoint-Spam-Info: AW1haW4tMjYwODE0MDA3NCBTYWx0ZWRfX0ULtzYbUIN/K jmQRBn1GWjHQJWqJgPDCe6cL1pdsGYdQIJznAJh5zHdXHKTrzsFsuFNXY1X5FPm18Ml/8pg6ZX1 c2WZZaMCGPJ5vSXoAe8BQqv5HjJvSAU= X-Authority-Analysis: v=2.4 cv=Z/Hc2nRA c=1 sm=1 tr=0 ts=6a7ee4c9 cx=c_pps a=rz3CxIlbcmazkYymdCej/Q==:117 a=ZePRamnt/+rB5gQjfz0u9A==:17 a=IkcTkHD0fZMA:10 a=Sv0fKeRqtYgA:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=rJkE3RaqiGZ5pbrm-msn:22 a=V9F15ByMrN-4acUeBR0A:9 a=3ZKOabzyN94A:10 a=QEXdDO2ut3YA:10 a=bFCP_H2QrGi7Okbo017w:22 X-Proofpoint-ORIG-GUID: mUQRupjBNMAjUyWRpZo3ete1hNtYYO47 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwODE0MDA3NCBTYWx0ZWRfX/1+ID/+8IXEM pn1/3UmBD1ACldpnUlUWi5LNX3cGEVXtLQA2nwui1qFncCf+idjt/EcKxu2g57wpewgvuFcRJls SEznCZ9SpS08Teb8wcM9Y3DP7va/r7kxAytToTJBj0xir2w7MQGbFHlmUoWCCz3s9wLVD1O5iwG QvzWF2ySgl/5NSdHAq7eXQ+ueKOmHg8RSXPc7royz/pO9okOYzbGK7oB4rtiYC99olinchYvr4k xy1SAbjgEdgeIl27EBEnuCBh/bECSPWc+BFtWjWJCcXPeG/wBfS9QaWauEwzfWHj3+p2iNjrSsz KThMIrfOdwtF3bVASCEKRQO93KO+hS3RdF4HpNW2oxRAp6xnL5YqMAyJwz/JbPcAX3eVkkVqgRJ WToNzgLpJsDp7/46aq/6vlJmXakYnvv1uddM+K4gT7ivaZckGkip9+VXjbbkLetMoEiAyVt4zdO V3CyeIhqUntC70oTS4w== X-Proofpoint-GUID: mUQRupjBNMAjUyWRpZo3ete1hNtYYO47 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-08-14_03,2026-08-12_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 phishscore=0 priorityscore=1501 adultscore=0 lowpriorityscore=0 bulkscore=0 malwarescore=0 clxscore=1015 spamscore=0 suspectscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2608140074 On 8/14/2026 12:01 PM, Krzysztof Kozlowski wrote: > On 14/08/2026 07:29, Vishnu Reddy wrote: >> On 8/13/2026 2:49 PM, Krzysztof Kozlowski wrote: >>> 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? >> dma-coherent tells the kernel that this device DMA path is hardware-coherent, >> so the SMMU maps its buffers as cacheable. That attribute is what causes the >> coherent interconnect to snoop CPU cache lines on every VPU transaction, so >> hardware keeps CPU caches and VPU-visible memory in sync — which is why the >> dma-coherent property lets us skip the unnecessary cache clean/invalidate. > You just repeated what I wrote. What for? > >> If a device doesn't support I/O coherence, its buffers would instead be mapped >> non-cacheable, no snooping would occur, and the driver would need explicit >> dma_sync_*() calls at each transition. Venus on SC7280 does support I/O >> coherence, so dma-coherent describes that existing hardware capability to >> the DMA subsystem. > How does this anyhow explain your commit msg? Are you saying driver is > buggy that it misses sync calls? No, driver is not buggy here. dma-coherent flag is missed in the dt node. > Best regards, > Krzysztof >