Re: [PATCH 09/73] ARM: tegra: gr2d is not backwards-compatible

[Thierry Reding <thierry.reding-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

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On Wed, Jun 17, 2020 at 07:21:30PM +0300, Dmitry Osipenko wrote:
> 16.06.2020 16:51, Thierry Reding пишет:
> > From: Thierry Reding <treding-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
> > 
> > The instantiation of gr2d in Tegra114 is not backwards-compatible with
> > the version found on earlier chips. Remove the misleading compatible
> > string.
> > 
> > Signed-off-by: Thierry Reding <treding-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
> > ---
> >  arch/arm/boot/dts/tegra114.dtsi | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/arch/arm/boot/dts/tegra114.dtsi b/arch/arm/boot/dts/tegra114.dtsi
> > index a0ac9ea9ec9d..d583dfba688f 100644
> > --- a/arch/arm/boot/dts/tegra114.dtsi
> > +++ b/arch/arm/boot/dts/tegra114.dtsi
> > @@ -35,7 +35,7 @@ host1x@50000000 {
> >  		ranges = <0x54000000 0x54000000 0x01000000>;
> >  
> >  		gr2d@54140000 {
> > -			compatible = "nvidia,tegra114-gr2d", "nvidia,tegra20-gr2d";
> > +			compatible = "nvidia,tegra114-gr2d";
> >  			reg = <0x54140000 0x00040000>;
> >  			interrupts = <GIC_SPI 72 IRQ_TYPE_LEVEL_HIGH>;
> >  			clocks = <&tegra_car TEGRA114_CLK_GR2D>;
> > 
> 
> Could you please explain what's the difference? AFAIK, the 2D HW is
> identical on T20/30/114.

My understanding is that the IP core itself is identical. However, the
compatible string really describes the integration of the IP, which in
case of Tegra114 is slightly different in that it's part of the HEG
power partition, whereas it wasn't previously.

That means that without knowledge of the power partition we won't be
able to access the gr2d IP on Tegra114 at all and hence it isn't
backwards compatible with Tegra20.

Thierry

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