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 1C407C433EF for ; Mon, 21 Feb 2022 07:10:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1345873AbiBUHLF (ORCPT ); Mon, 21 Feb 2022 02:11:05 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:34536 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230037AbiBUHLB (ORCPT ); Mon, 21 Feb 2022 02:11:01 -0500 Received: from perceval.ideasonboard.com (perceval.ideasonboard.com [213.167.242.64]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 628F7B69; Sun, 20 Feb 2022 23:10:38 -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 F3F61482; Mon, 21 Feb 2022 08:10:35 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1645427436; bh=ONkMNAtvkUZ/S9CvG5U6EYMEXS9davh/7VFRa++aVkA=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=iR1a55EP0fLRLdw+GbzSj2vGdFw1C2jT7Pvn3UK3+27d2W0XVzORX9EM5I/rchGsH uWAG1HMIvSAXXziZ55yrtShw7MBIjqfrSdXcDZk0vqLCLh7ytsu3ki6DX7WQ8Xzk2g 9ZIEqK8VtuDKlklH4tzd0zLjuN/R0Ko6ZwkXc6lU= Date: Mon, 21 Feb 2022 09:10:27 +0200 From: Laurent Pinchart To: Stefan Wahren Cc: Maxime Ripard , 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> <7ba0d8e7-72b9-d139-f29f-45a803ca2fdb@i2se.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <7ba0d8e7-72b9-d139-f29f-45a803ca2fdb@i2se.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Stefan, On Mon, Feb 14, 2022 at 12:32:59PM +0100, Stefan Wahren wrote: > Am 14.02.22 um 10:54 schrieb Laurent Pinchart: > > On Mon, Feb 14, 2022 at 10:39:54AM +0100, Maxime Ripard wrote: > >> 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. > > okay, as a result we need a DTS patch for bcm2835-rpi.dtsi to enable the > firmware clocks and its driver in this series. Can't we do that on top, enabling Unicam support for bcm2711 only first ? I have no idea how to deal with firmware clocks on bcm2825, and I'm not sure Jean-Michel even has a hardware platform to test it. If you want to send a patch series to enable firmware clocks on bcm2835, we'll be happy to rebase on top. -- Regards, Laurent Pinchart