linux-kernel - Re: [PATCH 3/3] ARM: bcm2835: Add VC4 to the device tree.

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Date:	Tue, 8 Mar 2016 11:12:13 -0700
From:	Stephen Warren <swarren@...dotorg.org>
To:	Eric Anholt <eric@...olt.net>
Cc:	linux-rpi-kernel@...ts.infradead.org,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	Lee Jones <lee@...nel.org>,
	Florian Fainelli <f.fainelli@...il.com>,
	Rob Herring <robh+dt@...nel.org>,
	Pawel Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>, devicetree@...r.kernel.org,
	dri-devel@...ts.freedesktop.org, David Airlie <airlied@...ux.ie>
Subject: Re: [PATCH 3/3] ARM: bcm2835: Add VC4 to the device tree.

On 03/08/2016 11:04 AM, Eric Anholt wrote:
> Stephen Warren <swarren@...dotorg.org> writes:
>
>> On 03/04/2016 01:32 PM, Eric Anholt wrote:
>>> VC4 is the GPU (display and 3D) present on the 283x.
>>
>>> diff --git a/arch/arm/boot/dts/bcm2835-rpi-a-plus.dts b/arch/arm/boot/dts/bcm2835-rpi-a-plus.dts
>>
>>> +&hdmi {
>>> +	hpd-gpios = <&gpio 46 GPIO_ACTIVE_LOW>;
>>> +};
>>
>> Isn't that the same everywhere? If so, adding it to bcm2835-rpi.dtsi
>> seems like a better idea; it'd avoid duplicating it everywhere.
>
> It's not the same everywhere (_HIGH vs _LOW), which is why it's in the
> individual files.

Oh right, it looks OK then. The series,
Acked-by: Stephen Warren <swarren@...dotorg.org>

One could reduce the duplication by moving the common block into the 
common .dtsi file, but using a board-defined #define for the polarity:

bcm2835-rpi-a-plus.dts:

#define RPI_HDMI_HPD_POLARITY
#include "bcm2835-rpi.dtsi"

bcm2835-rpi.dtsi:

&hdmi {
	hpd-gpios = <&gpio 46 RPI_HDMI_HPD_POLARITY>;
};

... although this case is so tiny I'm not sure there's any benefit 
trying to unify it like that right now.