Re: [PATCH] ARM: dts: exynos4212-tab3: limit usable memory range

[Artur Weber]

On 22.02.2024 16:55, Krzysztof Kozlowski wrote:
> On 21/02/2024 09:26, Krzysztof Kozlowski wrote:
> > On 19/02/2024 20:49, Artur Weber wrote:
> > > On 19.02.2024 08:44, Krzysztof Kozlowski wrote:
> > > > On 17/02/2024 20:02, Artur Weber wrote:
> > > > > The stock bootloader on the Samsung Galaxy Tab 3 8.0 provides an
> > > > > incorrect available memory range over ATAG_MEM. Limit the usable
> > > > > memory in the DTS to prevent it from doing so, without having to
> > > > > disable ATAG support.
> > > > >
> > > > > Signed-off-by: Artur Weber <aweber.kernel@xxxxxxxxx>
> > > > > ---
> > > > >    arch/arm/boot/dts/samsung/exynos4212-tab3.dtsi | 6 ++++++
> > > > >    1 file changed, 6 insertions(+)
> > > > >
> > > > > diff --git a/arch/arm/boot/dts/samsung/exynos4212-tab3.dtsi b/arch/arm/boot/dts/samsung/exynos4212-tab3.dtsi
> > > > > index e5254e32aa8f..9bc05961577d 100644
> > > > > --- a/arch/arm/boot/dts/samsung/exynos4212-tab3.dtsi
> > > > > +++ b/arch/arm/boot/dts/samsung/exynos4212-tab3.dtsi
> > > > > @@ -45,6 +45,12 @@ chosen {
> > > > >    		/* Default S-BOOT bootloader loads initramfs here */
> > > > >    		linux,initrd-start = <0x42000000>;
> > > > >    		linux,initrd-end = <0x42800000>;
> > > > > +
> > > > > +		/*
> > > > > +		 * Stock bootloader provides incorrect memory size in ATAG_MEM;
> > > > > +		 * override it here
> > > > > +		 */
> > > > > +		linux,usable-memory-range = <0x40000000 0x3fc00000>;
> > > >
> > > > Applied and dropped:
> > > >    chosen: linux,usable-memory-range:0: [4611686019496935424] is too short
> > >
> > > This seems to be a binding issue; the DT schema expects a 64-bit memory
> > > address and size, and doesn't allow a 32-bit range. I've tested the DTS
> > > on my device and this property seems to be handled fine, so I think this
> > > should allow 32-bit values as well.
> >
> > Regardless where is the issue: please test before sending.
> >
> > > I've opened a PR[1] against devicetree-org/dt-schema (where the schema
> > > for the chosen node is stored) to try and fix this. If my approach is
> > > incorrect, feel free to comment there as well.
> >
> >
> > According to Rob's comments, the DTS is the issue.
>
> With updated dtschema I still see the same warning. Is something else
> missing?

My bad, turns out I didn't test my dt-schemas patch correctly... looks
like this has been *properly* fixed now in latest dt-schema[1][2], and I
no longer get warnings about the linux,usable-memory-range property.
(There are some new warnings though, for some nodes in exynos4.dtsi that
have 2 reg values, but that's out of scope for this patch.)

Sorry for the general confusion, I'll make sure to double-check my
patches next time...

Best regards
Artur

[1] https://github.com/devicetree-org/dt-schema/commit/08eff8e6167e9e0bc1694af6c298b4584105a057
[2] https://github.com/devicetree-org/dt-schema/commit/c95c9ad63c51f8d9cfb258e6f17a8001efab6d64