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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 8D16AC433F5 for ; Tue, 8 Feb 2022 01:38:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=mCByG8fPEzKCSfMB4GH3E+wCfjx0iXelix6EEfKFxXM=; b=D5ic4duBGkZKxL B6m/kS7bWVG7/HcpGjoqeghaND+a1BX/p8K1QLrX1XlKaTei+s31nqdcWVx0owl8Z2pAyUy7v4Icj M2r31P+v/wapNAZGFhzRorBk+NGu5CNtostTAESTXnSuypG3712v8MtcoX/XpS/eYz9Im+TENXH0L RCpIzOEsnaz71To4ihfYnZeQLHq4xltYX+ulx4N/e5O+5Rs3wOiP+AVIUlOS2TDMcmMzcjsW0wiyw RtlONMaq6wy0Cp2+klJy0nDf6oT3+r49zsW5oZUIurNMEWjmvdTw1mcQBRsMgk21DCZBa/etAVStg 7cK1KFlQYN5t//oxBRjA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1nHFR0-00CCZk-9i; Tue, 08 Feb 2022 01:36:46 +0000 Received: from perceval.ideasonboard.com ([213.167.242.64]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1nHFQw-00CCYI-7b; Tue, 08 Feb 2022 01:36:44 +0000 Received: from pendragon.ideasonboard.com (62-78-145-57.bb.dnainternet.fi [62.78.145.57]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id A7B1F340; Tue, 8 Feb 2022 02:36:36 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1644284196; bh=QPrFMFxjzU7YGJv65FQNezHMqIiPR8D8MwVPLoKhFRE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Ty5Hr6oafXPAdfTKW9KW/lWJOjLTgKdYv7um/mBX3I12M9iHtgC/p6v4dFaz9CLo+ cBhEL4YARfhEoQbu1jWXdv4HTbf8ed8k4zhAwJittDaQEE0koRPgAigjtE0m3pk5EI /Ss+XZA3c1mCCQC6E7hamFkyz/oX/aHH9cun7yGg= Date: Tue, 8 Feb 2022 03:36:34 +0200 From: Laurent Pinchart To: Alexander Stein Cc: jeanmichel.hautbois@ideasonboard.com, linux-arm-kernel@lists.infradead.org, dave.stevenson@raspberrypi.com, devicetree@vger.kernel.org, kernel-list@raspberrypi.com, linux-kernel@vger.kernel.org, linux-media@vger.kernel.org, linux-rpi-kernel@lists.infradead.org, lukasz@jany.st, mchehab@kernel.org, naush@raspberrypi.com, robh@kernel.org, tomi.valkeinen@ideasonboard.com, nsaenz@kernel.org, bcm-kernel-feedback-list@broadcom.com Subject: Re: (EXT) Re: (EXT) [RFC PATCH v4 03/12] dt-bindings: media: Add bindings for bcm2835-unicam Message-ID: References: <20220203175009.558868-1-jeanmichel.hautbois@ideasonboard.com> <7954256.DvuYhMxLoT@steina-w> <5541132.DvuYhMxLoT@steina-w> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <5541132.DvuYhMxLoT@steina-w> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220207_173642_434202_C13286D6 X-CRM114-Status: GOOD ( 34.15 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi Alexander, On Mon, Feb 07, 2022 at 07:30:25AM +0100, Alexander Stein wrote: > Am Samstag, 5. Februar 2022, 03:22:51 CET schrieb Laurent Pinchart: > > On Fri, Feb 04, 2022 at 09:50:06AM +0100, Alexander Stein wrote: > > > Am Donnerstag, 3. Februar 2022, 18:50:00 CET schrieb Jean-Michel Hautbois: > > > > Introduce the dt-bindings documentation for bcm2835 CCP2/CSI2 Unicam > > > > camera interface. Also add a MAINTAINERS entry for it. > > > > > > > > Signed-off-by: Dave Stevenson > > > > Signed-off-by: Naushir Patuck > > > > Signed-off-by: Jean-Michel Hautbois > > > > > > > > --- > > > > v4: > > > > - make MAINTAINERS its own patch > > > > - describe the reg and clocks correctly > > > > - use a vendor entry for the number of data lanes > > > > --- > > > > > > > > .../bindings/media/brcm,bcm2835-unicam.yaml | 110 ++++++++++++++++++ > > > > 1 file changed, 110 insertions(+) > > > > create mode 100644 > > > > > > > > Documentation/devicetree/bindings/media/brcm,bcm2835-unicam.yaml > > > > > > > > diff --git > > > > a/Documentation/devicetree/bindings/media/brcm,bcm2835-unicam.yaml > > > > b/Documentation/devicetree/bindings/media/brcm,bcm2835-unicam.yaml > > > > new file mode 100644 > > > > index 000000000000..0725a0267c60 > > > > --- /dev/null > > > > +++ b/Documentation/devicetree/bindings/media/brcm,bcm2835-unicam.yaml > > > > @@ -0,0 +1,110 @@ > > > > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) > > > > +%YAML 1.2 > > > > +--- > > > > +$id: http://devicetree.org/schemas/media/brcm,bcm2835-unicam.yaml# > > > > +$schema: http://devicetree.org/meta-schemas/core.yaml# > > > > + > > > > +title: Broadcom BCM283x Camera Interface (Unicam) > > > > + > > > > +maintainers: > > > > + - Raspberry Pi Kernel Maintenance > > > > + > > > > +description: |- > > > > + The Unicam block on BCM283x SoCs is the receiver for either > > > > + CSI-2 or CCP2 data from image sensors or similar devices. > > > > + > > > > + The main platform using this SoC is the Raspberry Pi family of boards. > > > > + On the Pi the VideoCore firmware can also control this hardware block, > > > > + and driving it from two different processors will cause issues. > > > > + To avoid this, the firmware checks the device tree configuration > > > > + during boot. If it finds device tree nodes starting by csi then > > > > + it will stop the firmware accessing the block, and it can then > > > > + safely be used via the device tree binding. > > > > + > > > > +properties: > > > > + compatible: > > > > + const: brcm,bcm2835-unicam > > > > + > > > > + reg: > > > > + items: > > > > + - description: Unicam block. > > > > + - description: Clock Manager Image (CMI) block. > > > > + > > > > + interrupts: > > > > + maxItems: 1 > > > > + > > > > + clocks: > > > > + items: > > > > + - description: Clock to drive the LP state machine of Unicam. > > > > + - description: Clock for the vpu (core clock). > > > > + > > > > + clock-names: > > > > + items: > > > > + - const: lp > > > > + - const: vpu > > > > + > > > > + power-domains: > > > > + items: > > > > + - description: Unicam power domain > > > > + > > > > + brcm,num-data-lanes: > > > > + $ref: /schemas/types.yaml#/definitions/uint32 > > > > + enum: [ 2, 4 ] > > > > + description: Number of data lanes on the csi bus > > > > > > There is already data-lanes in > > > Documentation/devicetree/bindings/media/video- interfaces.yaml. AFAICS > > > these two are identical. Can't the video- > > > interface.yaml be used for this? I'm no expert TBH. > > > > This is the number of data lanes that the Unicam instance supports. > > There are two Unicam instances, and they can have 2 or 4 data lanes > > depending on the SoC. The data-lanes endpoint property indicates the > > number of lanes used on a particular board. > > Thanks for the explanation. Isn't this something which could be derived from > the compatible, e.g. having 2 different ones for 2 and 4 lanes respectively? > See [1] for a similar situation in the SPI subsystem. > I don't have a strong opinion, just want to share my feedback. Yes, it could also be done through compatible strings, but in this case I think a vendor-specific property is better. The number of lanes routed from the Unicam IP core to the external of the SoC depends on the exact SoC model, so we would need to create different compatible strings for essentially the same IP core. > [1] https://patchwork.kernel.org/project/spi-devel-general/patch/20211207104114.2720764-1-alexander.stein@ew.tq-group.com/#24641405 -- Regards, Laurent Pinchart _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel