linux-kernel - Re: [PATCH v2 4/8] arm64: dts: allwinner: Add ARM Mali GPU node for H6

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Message-ID: <5149757.GgN2G91tE9@jernej-laptop>
Date:   Thu, 11 Apr 2019 17:42:56 +0200
From:   Jernej Škrabec <jernej.skrabec@...l.net>
To:     Maxime Ripard <maxime.ripard@...tlin.com>
Cc:     Clément Péron <peron.clem@...il.com>,
        Rob Herring <robh+dt@...nel.org>, Chen-Yu Tsai <wens@...e.org>,
        Icenowy Zheng <icenowy@...c.io>,
        Jagan Teki <jagan@...rulasolutions.com>,
        devicetree <devicetree@...r.kernel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        dri-devel@...ts.freedesktop.org, linux-sunxi@...glegroups.com
Subject: Re: [PATCH v2 4/8] arm64: dts: allwinner: Add ARM Mali GPU node for H6

Dne četrtek, 11. april 2019 ob 17:27:52 CEST je Maxime Ripard napisal(a):
> On Thu, Apr 11, 2019 at 05:23:25PM +0200, Jernej Škrabec wrote:
> > Dne četrtek, 11. april 2019 ob 17:20:04 CEST je Clément Péron napisal(a):
> > > Hi,
> > > 
> > > On Thu, 11 Apr 2019 at 17:05, Jernej Škrabec <jernej.skrabec@...l.net>
> > 
> > wrote:
> > > > Dne četrtek, 11. april 2019 ob 12:57:16 CEST je Clément Péron 
napisal(a):
> > > > > Add the mali gpu node to the H6 device-tree.
> > > > > 
> > > > > Signed-off-by: Clément Péron <peron.clem@...il.com>
> > > > > ---
> > > > > 
> > > > >  arch/arm64/boot/dts/allwinner/sun50i-h6.dtsi | 14 ++++++++++++++
> > > > >  1 file changed, 14 insertions(+)
> > > > > 
> > > > > diff --git a/arch/arm64/boot/dts/allwinner/sun50i-h6.dtsi
> > > > > b/arch/arm64/boot/dts/allwinner/sun50i-h6.dtsi index
> > > > > e0dc4a05c1ba..196753110434 100644
> > > > > --- a/arch/arm64/boot/dts/allwinner/sun50i-h6.dtsi
> > > > > +++ b/arch/arm64/boot/dts/allwinner/sun50i-h6.dtsi
> > > > > @@ -157,6 +157,20 @@
> > > > > 
> > > > >                       allwinner,sram = <&ve_sram 1>;
> > > > >               
> > > > >               };
> > > > > 
> > > > > +             gpu: gpu@...0000 {
> > > > > +                     compatible = "allwinner,sun50i-h6-mali",
> > > > > +                                  "arm,mali-t720";
> > > > > +                     reg = <0x01800000 0x4000>;
> > > > > +                     interrupts = <GIC_SPI 84
> > > > 
> > > > IRQ_TYPE_LEVEL_HIGH>,
> > > > 
> > > > > +                                  <GIC_SPI 85
> > > > 
> > > > IRQ_TYPE_LEVEL_HIGH>,
> > > > 
> > > > > +                                  <GIC_SPI 83
> > > > 
> > > > IRQ_TYPE_LEVEL_HIGH>;
> > > > 
> > > > > +                     interrupt-names = "job", "mmu", "gpu";
> > > > > +                     clocks = <&ccu CLK_GPU>, <&ccu CLK_BUS_GPU>;
> > > > > +                     clock-names = "core", "bus";
> > > > > +                     resets = <&ccu RST_BUS_GPU>;
> > > > > +                     status = "disabled";
> > > > 
> > > > Usually self sufficient peripherals are enabled by default in DTSI.
> > > 
> > > I follow the other Mali Midgard (rk3399, rk3288) syntax.
> > > But I think you're right here, will go for an update I think.
> > 
> > I quickly checked A64 and H5 DTSI and both have GPU enabled by default
> > (status property is not set).
> 
> I asked myself the same question, but the H6 seems to have a supply
> wired to the GPU, while the H3 and H5 do not. So I'm not sure we want
> to enable it on all the boards, even though some might have left out
> the GPU supply which will result in a non-working GPU (I assume?)

It's true that GPU doesn't work at all without power supply. Even worse, ARM 
kernel driver just hangs whole SoC if it tries to use unpowered GPU.

I checked few datasheets and almost none of them have GPU power supply, except 
H5, where GPU is enabled by default in DTSI.

Yeah, I guess it's more safe to explicitly enable it in board DT.

Jernej