Re: [PATCH RFC 02/24] dt-bindings: add switch-delay property for mali-utgard

From: Rob Herring <robh@kernel.org>
To: Qiang Yu <yuq825@gmail.com>
Cc: Simon Shields <simon@lineageos.org>,
	devicetree@vger.kernel.org, Connor Abbott <cwabbott0@gmail.com>,
	Marek Vasut <marex@denx.de>,
	Neil Armstrong <narmstrong@baylibre.com>,
	Andrei Paulau <7134956@gmail.com>,
	dri-devel@lists.freedesktop.org,
	Vasily Khoruzhick <anarsoul@gmail.com>,
	Erico Nunes <nunes.erico@gmail.com>
Subject: Re: [PATCH RFC 02/24] dt-bindings: add switch-delay property for mali-utgard
Date: Wed, 23 May 2018 12:04:20 -0500	[thread overview]
Message-ID: <20180523170420.GA17409@rob-hp-laptop> (raw)
In-Reply-To: <20180518092815.25280-3-yuq825@gmail.com>

On Fri, May 18, 2018 at 05:27:53PM +0800, Qiang Yu wrote:
> Signed-off-by: Qiang Yu <yuq825@gmail.com>
> ---
>  Documentation/devicetree/bindings/gpu/arm,mali-utgard.txt | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/gpu/arm,mali-utgard.txt b/Documentation/devicetree/bindings/gpu/arm,mali-utgard.txt
> index c1f65d1dac1d..062d4bee216a 100644
> --- a/Documentation/devicetree/bindings/gpu/arm,mali-utgard.txt
> +++ b/Documentation/devicetree/bindings/gpu/arm,mali-utgard.txt
> @@ -58,6 +58,10 @@ Optional properties:
>      A power domain consumer specifier as defined in
>      Documentation/devicetree/bindings/power/power_domain.txt
>  
> +  - switch-delay:
> +    This value is the number of Mali clock cycles it takes to
> +    enable the power gates and turn on the power mesh.

This should be implied by the SoC specific compatible string.

Alternatively, can't the driver just pick a value long enough for 
everyone? Does it really vary that much, and is it timing critical?

Rob

P.S. Keep up the great work on this!
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