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 X-Spam-Level: X-Spam-Status: No, score=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9AE39C433E9 for ; Fri, 12 Mar 2021 21:49:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6E04A64F4C for ; Fri, 12 Mar 2021 21:49:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235349AbhCLVsy (ORCPT ); Fri, 12 Mar 2021 16:48:54 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41420 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235336AbhCLVsr (ORCPT ); Fri, 12 Mar 2021 16:48:47 -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 A44D0C061574; Fri, 12 Mar 2021 13:48:46 -0800 (PST) Received: from pendragon.ideasonboard.com (62-78-145-57.bb.dnainternet.fi [62.78.145.57]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id 5413A88F; Fri, 12 Mar 2021 22:48:42 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1615585722; bh=YjGll0lwHCNLMvaa5HHQOG2QmJDVwQWh4X+0YklqPIA=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=tyZBg3WiofgHqQi8Rmix0hCze5A6SlWG3WuFIEMT8kGlaLEzAxVnsVDRVap8q8SEV +OJthQ9GzDwC9qx5pE2IGmR3TTghf5EwvbZGrHbwvaS8XWHK9UcE23l0qqmEfTxgfI fvQIVsWjtYpUareuYE/qw3cpSooUnBfyEzCFWo8U= Date: Fri, 12 Mar 2021 23:48:07 +0200 From: Laurent Pinchart To: Rob Herring Cc: Sakari Ailus , devicetree@vger.kernel.org, "linux-kernel@vger.kernel.org" , Mauro Carvalho Chehab , Linux Media Mailing List Subject: Re: [PATCH] dt-bindings: media: Convert video-mux to DT schema Message-ID: References: <20210311234042.1588310-1-robh@kernel.org> <20210312072904.GA3@paasikivi.fi.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Rob, On Fri, Mar 12, 2021 at 08:33:06AM -0700, Rob Herring wrote: > On Fri, Mar 12, 2021 at 3:06 AM Laurent Pinchart wrote: > > On Fri, Mar 12, 2021 at 09:29:04AM +0200, Sakari Ailus wrote: > > > On Fri, Mar 12, 2021 at 03:25:11AM +0200, Laurent Pinchart wrote: > > > > On Thu, Mar 11, 2021 at 04:40:42PM -0700, Rob Herring wrote: > > > > > Now that we have the graph schema, convert the video-mux binding to DT > > > > > schema. > > > > > > > > > > Cc: Sakari Ailus > > > > > Cc: Laurent Pinchart > > > > > Cc: Mauro Carvalho Chehab > > > > > Cc: linux-media@vger.kernel.org > > > > > Signed-off-by: Rob Herring > > > > > --- > > > > > .../devicetree/bindings/media/video-mux.txt | 60 ------------ > > > > > .../devicetree/bindings/media/video-mux.yaml | 93 +++++++++++++++++++ > > > > > 2 files changed, 93 insertions(+), 60 deletions(-) > > > > > delete mode 100644 Documentation/devicetree/bindings/media/video-mux.txt > > > > > create mode 100644 Documentation/devicetree/bindings/media/video-mux.yaml > > > > > > > > > > diff --git a/Documentation/devicetree/bindings/media/video-mux.txt b/Documentation/devicetree/bindings/media/video-mux.txt > > > > > deleted file mode 100644 > > > > > index 63b9dc913e45..000000000000 > > > > > --- a/Documentation/devicetree/bindings/media/video-mux.txt > > > > > +++ /dev/null > > > > > @@ -1,60 +0,0 @@ > > > > > -Video Multiplexer > > > > > -================= > > > > > - > > > > > -Video multiplexers allow to select between multiple input ports. Video received > > > > > -on the active input port is passed through to the output port. Muxes described > > > > > -by this binding are controlled by a multiplexer controller that is described by > > > > > -the bindings in Documentation/devicetree/bindings/mux/mux-controller.txt > > > > > - > > > > > -Required properties: > > > > > -- compatible : should be "video-mux" > > > > > -- mux-controls : mux controller node to use for operating the mux > > > > > -- #address-cells: should be <1> > > > > > -- #size-cells: should be <0> > > > > > -- port@*: at least three port nodes containing endpoints connecting to the > > > > > - source and sink devices according to of_graph bindings. The last port is > > > > > - the output port, all others are inputs. > > > > > - > > > > > -Optionally, #address-cells, #size-cells, and port nodes can be grouped under a > > > > > -ports node as described in Documentation/devicetree/bindings/graph.txt. > > > > > - > > > > > -Example: > > > > > - > > > > > - mux: mux-controller { > > > > > - compatible = "gpio-mux"; > > > > > - #mux-control-cells = <0>; > > > > > - > > > > > - mux-gpios = <&gpio1 15 GPIO_ACTIVE_HIGH>; > > > > > - }; > > > > > - > > > > > - video-mux { > > > > > - compatible = "video-mux"; > > > > > - mux-controls = <&mux>; > > > > > - #address-cells = <1>; > > > > > - #size-cells = <0>; > > > > > - > > > > > - port@0 { > > > > > - reg = <0>; > > > > > - > > > > > - mux_in0: endpoint { > > > > > - remote-endpoint = <&video_source0_out>; > > > > > - }; > > > > > - }; > > > > > - > > > > > - port@1 { > > > > > - reg = <1>; > > > > > - > > > > > - mux_in1: endpoint { > > > > > - remote-endpoint = <&video_source1_out>; > > > > > - }; > > > > > - }; > > > > > - > > > > > - port@2 { > > > > > - reg = <2>; > > > > > - > > > > > - mux_out: endpoint { > > > > > - remote-endpoint = <&capture_interface_in>; > > > > > - }; > > > > > - }; > > > > > - }; > > > > > -}; > > > > > diff --git a/Documentation/devicetree/bindings/media/video-mux.yaml b/Documentation/devicetree/bindings/media/video-mux.yaml > > > > > new file mode 100644 > > > > > index 000000000000..780fbbd46a38 > > > > > --- /dev/null > > > > > +++ b/Documentation/devicetree/bindings/media/video-mux.yaml > > > > > @@ -0,0 +1,93 @@ > > > > > +# SPDX-License-Identifier: GPL-2.0 > > > > > +%YAML 1.2 > > > > > +--- > > > > > +$id: http://devicetree.org/schemas/media/video-mux.yaml# > > > > > +$schema: http://devicetree.org/meta-schemas/core.yaml# > > > > > + > > > > > +title: Video Multiplexer > > > > > + > > > > > +maintainers: > > > > > + - Sakari Ailus > > > > > + - Laurent Pinchart > > > > > + > > > > > +description: > > > > > + Video multiplexers allow to select between multiple input ports. Video > > > > > + received on the active input port is passed through to the output port. Muxes > > > > > + described by this binding are controlled by a multiplexer controller. > > > > > + > > > > > +properties: > > > > > + compatible: > > > > > + const: video-mux > > > > > + > > > > > + mux-controls: > > > > > + maxItems: 1 > > > > > + > > > > > + '#address-cells': > > > > > + const: 1 > > > > > + > > > > > + '#size-cells': > > > > > + const: 0 > > > > > + > > > > > + ports: > > > > > + $ref: /schemas/graph.yaml#/properties/ports > > > > > + > > > > > + patternProperties: > > > > > + '^port@': > > > > > + $ref: /schemas/graph.yaml#/properties/port > > > > > > > > Should we require at least port@0, port@1 and port@2 ? > > > > > > > > > + > > > > > +patternProperties: > > > > > + '^port@': > > > > > + $ref: /schemas/graph.yaml#/properties/port > > > > > + description: > > > > > + At least three port nodes containing endpoints connecting to the source > > > > > + and sink devices according to of_graph bindings. The last port is the > > > > > + output port, all others are inputs. > > > > > + > > > > > +required: > > > > > + - compatible > > > > > + - mux-controls > > > > > > > > Should a constraint be added to ensure that either a ports node or > > > > port@0, port@1 and port@2 nodes exists ? > > > > > > It's not meaningful to have this device without such nodes. But a mux with > > > more ports could be connected in a way that leaves one or both of ports 1 > > > and 2 unconnected. It's still not a likely configuration but a possible > > > one. > > > > Those ports wouldn't be connected, but they could still exist in DT. > > Could or must? I think we could have both cases. If there's never a > connection on a board no point in having the node there. If there's a > possible connection (via a connector and overlay), then we may want > the node. I tend to treat ports as mandatory and endpoints as optional, as the former describe a intrinsic property of the device and the latter a connection in a specific system. Looking at the video-mux driver, it first finds the number of the last port, and then creates N V4L2 subdev pads, regardless of whether a port exists for it. There's thus an implicit assumption that ports will be numbered 0 to N-1 and will all exist. If a port doesn't exist in DT, the driver should still operate correctly as far as I can tell, but it will in any case create N pads. Now, that's a driver implementation, but given that the bindings are for a generic mux device, the driver matters here. I'd be fine making ports optional and modifying the driver, or making them mandatory in DT, but I think it's important to at least synchronize the bindings and the driver. -- Regards, Laurent Pinchart