Re: [PATCH v2 0/2] Add support for bcm2711 in vchiq_arm

From: Stefan Wahren <stefan.wahren@i2se.com>
To: Adrien Thierry <athierry@redhat.com>, linux-kernel@vger.kernel.org
Cc: Rob Herring <robh+dt@kernel.org>,
	Nicolas Saenz Julienne <nsaenz@kernel.org>,
	Florian Fainelli <f.fainelli@gmail.com>,
	Ray Jui <rjui@broadcom.com>,
	Scott Branden <sbranden@broadcom.com>,
	bcm-kernel-feedback-list@broadcom.com,
	devicetree@vger.kernel.org, linux-rpi-kernel@lists.infradead.org,
	linux-arm-kernel@lists.infradead.org,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Gaston Gonzalez <gascoar@gmail.com>,
	Ojaswin Mujoo <ojaswin98@gmail.com>,
	linux-staging@lists.linux.dev,
	Krzysztof Kozlowski <krzk@kernel.org>
Subject: Re: [PATCH v2 0/2] Add support for bcm2711 in vchiq_arm
Date: Sat, 26 Mar 2022 10:04:13 +0100	[thread overview]
Message-ID: <d20fd8f2-c47a-2f3e-4efa-be705f1517b9@i2se.com> (raw)
In-Reply-To: <20220324172647.167617-1-athierry@redhat.com>

Hi Adrien,

Am 24.03.22 um 18:26 schrieb Adrien Thierry:
> The goal of this patch series is to use the bcm2711 compatible string in
> vchiq_arm for the Raspberry Pi 4.

there was already a patch series to enable VCHIQ on BCM2711, which 
wasn't accepted:

https://lore.kernel.org/linux-arm-kernel/20211014223230.451659-1-mguma@redhat.com/T/

Could you please explain your approach, especially leaving out 36 bit 
DMA support?

>   This allows using the downstream device
> tree with the upstream kernel.

This is a really bad idea and caused a lot of trouble in the past. A lot 
of the issues in the Fedora or Arch Linux forums or mailing lists 
results from this idea. It wastes the time of the kernel developer since 
these DT files has never been reviewed by the devicetree maintainers.

Best regards

>
> ---
> Changes since v1:
> - Removed duplicate compatible string for bcm2711 in
>    brcm,bcm2835-vchiq.yaml
>
> Adrien Thierry (2):
>    dt-bindings: soc: bcm: bcm2835-vchiq: Add support for bcm2711
>    staging: vchiq_arm: Use bcm2711 compatible string for bcm2711-based
>      RPi
>
>   .../devicetree/bindings/soc/bcm/brcm,bcm2835-vchiq.yaml      | 5 +++++
>   arch/arm/boot/dts/bcm2711-rpi.dtsi                           | 1 +
>   .../staging/vc04_services/interface/vchiq_arm/vchiq_arm.c    | 5 +++++
>   3 files changed, 11 insertions(+)
>
>
> base-commit: ed4643521e6af8ab8ed1e467630a85884d2696cf