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 1EB6D44471A; Tue, 11 Aug 2026 13:51:05 +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=1786456271; cv=none; b=AO29SftDuPO8Gm/M0FYyy5xIHWgO2AYVKRB0mB0R0yyf9WpJWOxwtNm4Xw7N7bOpF2ELTnuSnDxCxsVkK+QAaG3/ODYuPX6sTsUSYzN4SekN+nhlU0zZzFpAgjOthyHbEhYJouEsJRE6TG42EfPPxpWKWHoUdday+cT8wNtfjlg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786456271; c=relaxed/simple; bh=5iL4OIqPlnJLrumaa43NF/fSPoVB00e4dXiibyZACiM=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=ECFny9MznZNbAK56QAUD8JDahfwZ5noCw3PEp+I7dlYKpmoCDHofRDgmWXJWRrjpsjZ3lXE2rtroQgnhs47q6yOtyJ+kDjOV5X/3CIlBguVr3I9KvFbEPxdX6AWQeyEayRdAvu+Fqa22w3uah2rGV4TcGUflhxLyviRQUIJxXNg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Pr/jdJwV; 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="Pr/jdJwV" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0BFB21F000E9; Tue, 11 Aug 2026 13:51:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1786456264; bh=UBILun7qPRptwdmu9LCu16xBfULu1xWnFXYbEEW192A=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=Pr/jdJwVl2BAIFet6tFrv/tq2Rj7SBciCOYgZ+pQTaB0TW69p+af7SQJOW4ct4cWu CtZq5jvp2qrSimo9emVQFv73rhPiyzSsI5XREB3fHFdItgbfRidweEym2Am5+TDtNq sng4oguvcHWVLkroXjBEq1O6uyG5+hsYYxePMbIxFOI2fQSDKadHR5w7U+EgetN7AQ vWo/Q7w0/LNrDPMI1cA41gGXw7ag03xDOoqsFEB3srkfA9U8DvslxV0eYYv+fp+EJc SjUSlnuX7p4Xs9Ju23Hw78yXl+JEHbivn0YOo7qFX2YQQtMl+prt5tD6NaAE75d3QA XxZR+FhSpHsZQ== Date: Tue, 11 Aug 2026 08:51:03 -0500 From: Rob Herring To: Vishnu Reddy Cc: Bryan O'Donoghue , Vikash Garodia , Dikshita Agarwal , Mauro Carvalho Chehab , 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 1/4] dt-bindings: media: qcom,sc7280-venus: Add dma-coherent property Message-ID: <20260811135103.GA2063083-robh@kernel.org> References: <20260801-iris-fixes-dma-pseq-fint-v1-0-aba0cb22f6ab@oss.qualcomm.com> <20260801-iris-fixes-dma-pseq-fint-v1-1-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=us-ascii Content-Disposition: inline In-Reply-To: <20260801-iris-fixes-dma-pseq-fint-v1-1-aba0cb22f6ab@oss.qualcomm.com> On Sat, Aug 01, 2026 at 01:07:27PM +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. The only side effect of 'dma-coherent' not being present should be doing unnecessary cache flushes. It should still work. Maybe you are missing some DMA API sync functions? Rob