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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D66E1C41535 for ; Mon, 14 Feb 2022 10:21:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1347561AbiBNKVU (ORCPT ); Mon, 14 Feb 2022 05:21:20 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:48252 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1347953AbiBNKRA (ORCPT ); Mon, 14 Feb 2022 05:17:00 -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 7DA188CD97; Mon, 14 Feb 2022 01:54:26 -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 79C3A47F; Mon, 14 Feb 2022 10:54:23 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1644832463; bh=aUVnJ4wIPvMcFSf1znk2gPQHK2Wcph2lWqBu4+e+lV4=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=J9Y5iGHHtcuiXm1vvqsm7FI1Bmbq+pu61xCQMZDMvj7rRyF3kszrjZ+y6DsCM0TnZ qKBISSaCdg1yUWMGiMjhs6uz203wbs8LFhQs4u+vwuty7NMCwH0YM7jro1IAKdjmQ3 acjj1kcM7G9+RL15zhtS2JSj1ZTs1Lem1JJSnkAg= Date: Mon, 14 Feb 2022 11:54:17 +0200 From: Laurent Pinchart To: Maxime Ripard Cc: Stefan Wahren , Jean-Michel Hautbois , dave.stevenson@raspberrypi.com, devicetree@vger.kernel.org, kernel-list@raspberrypi.com, linux-arm-kernel@lists.infradead.org, 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, bcm-kernel-feedback-list@broadcom.com, Florian Fainelli Subject: Re: [PATCH v5 03/11] dt-bindings: media: Add bindings for bcm2835-unicam Message-ID: References: <20220208155027.891055-1-jeanmichel.hautbois@ideasonboard.com> <20220208155027.891055-4-jeanmichel.hautbois@ideasonboard.com> <20220214093954.5y4jbqcddmwhgxr5@houat> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20220214093954.5y4jbqcddmwhgxr5@houat> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Feb 14, 2022 at 10:39:54AM +0100, Maxime Ripard wrote: > Hi, > > On Sun, Feb 13, 2022 at 04:48:45PM +0100, Stefan Wahren wrote: > > as someone with a little more insight to the clocks, i like to know your > > opinion about the bcm2835-unicam binding. > > > > Am 08.02.22 um 16:50 schrieb Jean-Michel Hautbois: > > > Introduce the dt-bindings documentation for bcm2835 CCP2/CSI2 Unicam > > > camera interface. > > > > > > Signed-off-by: Dave Stevenson > > > Signed-off-by: Naushir Patuck > > > Signed-off-by: Jean-Michel Hautbois > > > Reviewed-by: Laurent Pinchart > > > > > > --- > > > 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 | 117 ++++++++++++++++++ > > > 1 file changed, 117 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..1938ace23b3d > > > --- /dev/null > > > +++ b/Documentation/devicetree/bindings/media/brcm,bcm2835-unicam.yaml > > > @@ -0,0 +1,117 @@ > > > +# 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 whose name starts with '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. > > > + > > > + reg-names: > > > + items: > > > + - const: unicam > > > + - const: cmi > > > + > > > + 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 > > > + > > > > according to this patch [1], the unicam driver only needs the VPU clock > > reference just to enforce a minimum of 250 MHz. The firmware clock > > binding and its driver is specific to the bcm2711, but the Unicam IP > > exists since bcm2835. > > > > So do you think the clock part is correct or should be the VPU clock > > optional? > > I think we should keep it mandatory. Indeed, that clock is shared with > the HVS that will change its rate on a regular basis, so even just > enforcing that 250MHz while it's on without a clock handle will be > fairly hard. > > Also, those are the constraints we have now, but having the clock handle > all the time will allow us to add any constraint we might need in the > future. > > And BCM2711 or not, the clock has probably always been there. Furthermore, regardless of what the driver needs, Unicam operates with the VPU clock, so I think it makes sense to reference it in the device tree. -- Regards, Laurent Pinchart