From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from perceval.ideasonboard.com (perceval.ideasonboard.com [213.167.242.64]) (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 AE5D3145FE0; Sun, 5 Apr 2026 20:14:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=213.167.242.64 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775420084; cv=none; b=eoEXueb8y8pYLK/xIEbY6B5vpN5hRcBtT5fO5xkjW2Vph/gun9k5BcfOALhUBZlpQZBdq7OXW2SlvJ9wQ5xzEHOuadYp8Y5cCSMTTjDxf3y8KP7Tovo7yAXraOSht51EK/+/20CaBIApFqhDNh2q8yoT3ITxzpWkw7jtqQkx9N4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775420084; c=relaxed/simple; bh=b+kYfFusrvnvd/tWkcfi4fGgeWnGzPTiLK2UY6hE0TY=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=pze7mhcGMpjYG+AL03fZaOANz7Jv78+7YNpoGaXQg4+Awf+g0OGpYrt/GYwOfRORbk00syg7A7ZOHU/pf4nQrl7pWA/ykoIb2zjOaxtA8/TJ4pmAG7XZXKqsJ47kpfNNgnHi6OL5aIcrf4eHPMLlRPL1KzqehsgSkL+n/lWNEAs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=ideasonboard.com; spf=pass smtp.mailfrom=ideasonboard.com; dkim=pass (1024-bit key) header.d=ideasonboard.com header.i=@ideasonboard.com header.b=SlZcAMsh; arc=none smtp.client-ip=213.167.242.64 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=ideasonboard.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=ideasonboard.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=ideasonboard.com header.i=@ideasonboard.com header.b="SlZcAMsh" Received: from killaraus.ideasonboard.com (2001-14ba-703d-e500--2a1.rev.dnainternet.fi [IPv6:2001:14ba:703d:e500::2a1]) by perceval.ideasonboard.com (Postfix) with UTF8SMTPSA id 6493A6AF; Sun, 5 Apr 2026 22:13:14 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1775419994; bh=b+kYfFusrvnvd/tWkcfi4fGgeWnGzPTiLK2UY6hE0TY=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=SlZcAMsheDamWDUNSvO7ieEaL6TSXo+afjIKNcczS76M9bZpxZm4UzhxJonxpeY4x U5JRaGWo6mARM37aJ6PLnvMRQy0HKdN2viUUdbK2gWcEecGEonexz7OqV3lpJ8IIMO CTjz8xKpFZQ/TtBsC7jrgDXgpgYUH14Y103HzuE4= Date: Sun, 5 Apr 2026 23:14:39 +0300 From: Laurent Pinchart To: Dmitry Baryshkov Cc: Bryan O'Donoghue , johannes.goede@oss.qualcomm.com, Loic Poulain , vladimir.zapolskiy@linaro.org, kieran.bingham@ideasonboard.com, robh@kernel.org, krzk+dt@kernel.org, andersson@kernel.org, konradybcio@kernel.org, linux-media@vger.kernel.org, linux-arm-msm@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, mchehab@kernel.org Subject: Re: [RFC PATCH 2/3] media: qcom: camss: Add CAMSS Offline Processing Engine driver Message-ID: <20260405201439.GC1213462@killaraus.ideasonboard.com> References: <12194cc0-0960-486c-be7e-1a22d95de340@kernel.org> <7fc31426-3157-49c7-a30d-dcd7b181fcc6@oss.qualcomm.com> <8DTHyPLaUjGKd83PvBsisjn_SnpUnvkateTtwz9P6CChP9VGfDyQmJa4Rfd5KwOBOLhtGFJPDzfHrXC4zvV-Fg==@protonmail.internalid> <0330f63f-7137-4484-954a-fc0776a9b052@oss.qualcomm.com> <0879e4c1-5381-4a70-9fb3-4af9b3bf6e48@kernel.org> <4hasliun3wkook2pvfkntjlzs7elu67ine5q7nd7ptjthx5qvw@rntvb7lnajpc> Precedence: bulk X-Mailing-List: devicetree@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: <4hasliun3wkook2pvfkntjlzs7elu67ine5q7nd7ptjthx5qvw@rntvb7lnajpc> On Mon, Mar 30, 2026 at 09:55:23PM +0300, Dmitry Baryshkov wrote: > On Mon, Mar 30, 2026 at 03:11:58PM +0100, Bryan O'Donoghue wrote: > > On 30/03/2026 14:46, johannes.goede@oss.qualcomm.com wrote: > > > > > And then your CCMv1 or CCMv2 helper will get called with > > > > > the matching parameter-data. > > > > > > > > This leads to userspace having to know exact format for each hardware > > > > version, which is not nice. At the very least it should be possible to > > > > accept CCMv1 buffers and covert them to CCMv2 when required. > > > > > > Yes, but a new ISP may also have a different pipeline altogether > > > with e.g. more then one preview/viewfinder output vs one viewfinder > > > output for current hw, etc. > > > > My scoping on HFI shows that the IQ structures between Kona and later > > versions have pretty stable data-structures. > > > > It might be worthwhile for the non-HFI version to implement those > > structures. > > > > I keep mentioning CDM. Its also possible to construct the buffer in the > > format the CDM would require and hand that from user-space into the kernel. > > > > That would save alot of overhead translating from one format to another. > > > > That's another reason I bring up CDM again and again. We probably don't want > > to fix to the wrong format for OPE, introduce the CDM and then find we have > > to map from one format to another for large and complex data over and over > > again for each frame or every N frames. > > > > TBH I think the CDM should happen for this system and in that vein is there > > any reason not to pack the data in the order the CDM will want ? > > This sounds like the most horrible idea: letting userspace directly > program any registers in a way that is not visible to the kernel. ISP hardware is typically not designed to make this safe, so I would be really, really careful about going in that direction. It also seems a dangerous idea to me. > > So probably in fact IQ structs are not the right thing for OPE+IFE. -- Regards, Laurent Pinchart