linux-kernel - Re: Re: [PATCH RFC v2 04/11] ARM: dts: omap4: Add device tree entry for SGX GPU

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Message-ID: <vpcgccul53oibwoqb3barj3rjxoyskoldjyfvjdzmytic3tonm@wq4aqsenk7rp>
Date: Mon, 15 Jan 2024 09:25:30 +0100
From: Maxime Ripard <mripard@...nel.org>
To: "H. Nikolaus Schaller" <hns@...delico.com>
Cc: Andrew Davis <afd@...com>, Frank Binns <frank.binns@...tec.com>, 
	Donald Robson <donald.robson@...tec.com>, Matt Coster <matt.coster@...tec.com>, 
	Adam Ford <aford173@...il.com>, Ivaylo Dimitrov <ivo.g.dimitrov.75@...il.com>, 
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, Thomas Zimmermann <tzimmermann@...e.de>, 
	Rob Herring <robh+dt@...nel.org>, Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>, 
	Conor Dooley <conor+dt@...nel.org>, Chen-Yu Tsai <wens@...e.org>, 
	Jernej Skrabec <jernej.skrabec@...il.com>, Samuel Holland <samuel@...lland.org>, 
	Benoît Cousson <bcousson@...libre.com>, Tony Lindgren <tony@...mide.com>, Nishanth Menon <nm@...com>, 
	Vignesh Raghavendra <vigneshr@...com>, Tero Kristo <kristo@...nel.org>, 
	Paul Cercueil <paul@...pouillou.net>, dri-devel@...ts.freedesktop.org, devicetree@...r.kernel.org, 
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, 
	linux-sunxi@...ts.linux.dev, linux-omap@...r.kernel.org, linux-mips@...r.kernel.org
Subject: Re: Re: [PATCH RFC v2 04/11] ARM: dts: omap4: Add device tree entry
 for SGX GPU

Hi,

On Fri, Jan 12, 2024 at 06:33:58PM +0100, H. Nikolaus Schaller wrote:
> > Am 08.01.2024 um 19:32 schrieb Andrew Davis <afd@...com>:
> > 
> > Add SGX GPU device entry to base OMAP4 dtsi file.
> > 
> > Signed-off-by: Andrew Davis <afd@...com>
> > ---
> > arch/arm/boot/dts/ti/omap/omap4.dtsi | 9 +++++----
> > 1 file changed, 5 insertions(+), 4 deletions(-)
> > 
> > diff --git a/arch/arm/boot/dts/ti/omap/omap4.dtsi b/arch/arm/boot/dts/ti/omap/omap4.dtsi
> > index 2bbff9032be3e..559b2bfe4ca7c 100644
> > --- a/arch/arm/boot/dts/ti/omap/omap4.dtsi
> > +++ b/arch/arm/boot/dts/ti/omap/omap4.dtsi
> > @@ -501,10 +501,11 @@ sgx_module: target-module@...00000 {
> > #size-cells = <1>;
> > ranges = <0 0x56000000 0x2000000>;
> > 
> > - /*
> > - * Closed source PowerVR driver, no child device
> > - * binding or driver in mainline
> > - */
> > + gpu@0 {
> 
> I wonder why we don't add a "gpu:" label here.
> 
> Almost all other subsystem nodes have one (e.g. emif:, aes:, dss:, dsi:, hdmi:, etc.),
> obviously for convenience when using a .dtsi file.
> 
> It would allow a board-specific DTS to easily add status = "disabled" to avoid driver
> probing or disabling the GPU (e.g. if there is no display).

There's no reason to disable it in the DT: the hardware block would
still be there and it's rendering to memory so it still could be useful.

If there's no display on the board and you really don't want the GPU
driver, then you can disable the driver or block the module loading, but
it should be a distro / package / user decision, not a DT / kernel one
still.

Maxime

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