From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B91D0C433FE for ; Wed, 10 Nov 2021 16:57:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9D12F61107 for ; Wed, 10 Nov 2021 16:57:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231608AbhKJRAR (ORCPT ); Wed, 10 Nov 2021 12:00:17 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47870 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230101AbhKJRAQ (ORCPT ); Wed, 10 Nov 2021 12:00:16 -0500 Received: from perceval.ideasonboard.com (perceval.ideasonboard.com [IPv6:2001:4b98:dc2:55:216:3eff:fef7:d647]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 60B98C061764; Wed, 10 Nov 2021 08:57:28 -0800 (PST) Received: from pendragon.ideasonboard.com (117.145-247-81.adsl-dyn.isp.belgacom.be [81.247.145.117]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id 414993F6; Wed, 10 Nov 2021 17:57:25 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1636563445; bh=HWCdrn+CM5R0wXsLQQBhhSRZ09eJhnXW2C2/3jxS8JM=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=jVCGe/0NIvQVwctHiVdlsZq2vt0c+9FY3ADpQjsTY5o9ZDeNCDb6KGsEN4en4gu+R +4y0Vt85mlubH2pPWe2w6hjcNB18J0tUM1Tc4wg+fsx9nzH0jJNLYu7cLpyStMxLyF RN35CreVH3D6rw3PI+obLae1dB1wVE9vsGSwfO/c= Date: Wed, 10 Nov 2021 18:57:04 +0200 From: Laurent Pinchart To: Niklas =?utf-8?Q?S=C3=B6derlund?= Cc: Hans Verkuil , Jacopo Mondi , linux-media@vger.kernel.org, linux-renesas-soc@vger.kernel.org Subject: Re: [PATCH 0/3] media: rcar-{csi2,vin}: Move to full Virtual Channel routing per CSI-2 IP Message-ID: References: <20211020200225.1956048-1-niklas.soderlund+renesas@ragnatech.se> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org On Wed, Nov 10, 2021 at 05:01:31PM +0100, Niklas Söderlund wrote: > Hi Laurent, > > On 2021-11-10 17:25:54 +0200, Laurent Pinchart wrote: > > Hi Niklas, > > > > On Wed, Oct 20, 2021 at 10:02:22PM +0200, Niklas Söderlund wrote: > > > Hello, > > > > > > This series attempts to increase the flexibility of the R-Car VIN > > > capture pipeline by allowing for free form Virtual Channel routing > > > within the same CSI-2 IP block. > > > > > > When Gen3 support was first added to this R-Car VIN and CSI-2 driver the > > > routing was centred around the CHSEL register which multiplex the > > > different parallel buses that sits between the CSI-2 receivers source > > > side and the VIN dma engines. This was a bad design as the multiplexing > > > do allow for only a few combinations and do not play nice with many > > > video streams in the system. > > > > > > For example it's only possible for CSI-2 Virtual Channels 0 and 1 of any > > > given CSI-2 receiver to be used together with the scaler. > > > > > > Later datasheets have expanded the documentation and it is now possible > > > to improve on this design by allowing any Virtual Channel to be routed > > > to any R-Car VIN instance, provided that there exists a parallel bus > > > between them. This increases the flexibility as all Virtual Channels can > > > now be used together with the scaler for example. > > > > > > The redesign is not however perfect. While the new design allows for > > > many more routes, two constrains limit a small portion of routes that > > > was possible in the old design but are no more. > > > > > > - It is no longer possible to route the same CSI-2 and VC to more then > > > one VIN at a time. This was theoretically possible before if the > > > specific SoC allowed for the same CSI-2 and VC to be routed to two > > > different VIN capture groups. > > > > Does it mean we can't capture image data and embedded data from the same > > camera sensor in separate buffers ? > > On the contrary. Without this change we can't capture any embedded data. > With this patch we still can't capture it, unless the R-Car CSI-2 > receiver lies. But with this applied we are closer to enable meta data > to reach user space. How do you envision this being done ? > > > - It is no longer possible to simultaneously mix links from two CSI-2 IP > > > blocks to the same VIN capture group. > > > > > > For example if VIN2 is capturing from CSI40 then VIN{0,1,3} must also > > > capture from CSI40. While VIN{4,5,6,7} is still free to capture from > > > any other CSI-2 IP in the system. Once all VIN{0,1,2,3} links to CSI40 > > > are disabled that VIN capture group is free again to capture from any > > > other CSI-2 IP it is connected to. > > > > What practical limitation does this bring, does it forbid any useful use > > case ? > > Yes and no ;-). It limits a small set of use-cases, while enabling a > great many more. In the old setup you are allowed to route a mix of Rx > to Tx intermixing a few of the modules 1:1 as an exception. With this > change you get routing n:to:n with a few exceptions. That I understand, but are there any exceptions that were previously allowed that you think map to important use cases ? > > > At the core of the redesign is greater cooperator of the R-Car VIN and > > > CSI-2 drivers in configuring the routing. The VIN driver is after this > > > change only responsible to configure the full VIN capture groups > > > parallel buses to be to a particular CSI-2 IP. While the configuration > > > of which CSI-2 Virtual Channel is outputted on which of the R-Car CSI-2 > > > IP output ports is handled by the CSI-2 driver. > > > > > > Before this change the CSI-2 Virtual Channel to output port was static > > > in the CSI-2 driver and the different links only manipulated the VIN > > > capture groups CHSEL register. With this change both the CHSEl register > > > and the CSI-2 routing VCDT registers are modified for greater > > > flexibility. > > > > > > Patch 1/3 and 2/3 are cleanup patches moving code around preparing for > > > the real work in 3/3. The work is based on the latest media-tree. > > > > > > Kind Regards, > > > Niklas Söderlund > > > > > > Niklas Söderlund (3): > > > media: rcar-vin: Refactor link notify > > > media: rcar-vin: Breakout media link creation > > > media: rcar-{csi2,vin}: Move to full Virtual Channel routing per CSI-2 > > > IP > > > > > > drivers/media/platform/rcar-vin/rcar-core.c | 379 ++++++-------------- > > > drivers/media/platform/rcar-vin/rcar-csi2.c | 58 ++- > > > drivers/media/platform/rcar-vin/rcar-dma.c | 2 +- > > > drivers/media/platform/rcar-vin/rcar-vin.h | 18 +- > > > 4 files changed, 167 insertions(+), 290 deletions(-) -- Regards, Laurent Pinchart