[PATCH] ARM: dts: meson: Fixing L2 cache controller node for Meson8 and Meson8b

[Emiliano Ingrassia]

Hi Martin,

thanks for the review.

On Fri, Jul 28, 2017 at 01:54:39PM +0200, Martin Blumenstingl wrote:
> Hi Emiliano,
> 
> many thanks for looking into this (and providing detailed information)!
> 
> On Wed, Jul 26, 2017 at 11:55 AM, Emiliano Ingrassia
> <ingrassia at epigenesys.com> wrote:
> > Hi Martin,
> >
> > thank you for the quick response!
> >
> > On Tue, Jul 25, 2017 at 08:51:15PM +0200, Martin Blumenstingl wrote:
> >> Hi Emiliano,
> >>
> >> On Tue, Jul 25, 2017 at 5:23 PM, Emiliano Ingrassia
> >> <ingrassia at epigenesys.com> wrote:
> >> > Changing address filtering range to support the entire DDR region.
> >> > The previous range prevents ODROID-C1+ board from booting.
> >> thanks for the patch!
> >> could you please explain what issue you are seeing exactly? kernelci
> >> also has an Odroid-C1 in it's farm and it seems to boot mainline
> >> (4.13-rc2+) just fine, see: [0]
> >>
> >
> > The issue I'm seeing is simple: I have an ODROID-C1+ board (rev 0.4 20150930)
> > which does not boot with the L2 cache controller filtering range set to <0x1000000 0xc0000000>.
> > U-Boot launches the kernel, which decompression complete successfully, but then nothing happens.
> thank you for explaining this - would you please put this info into
> the commit message?
>

Of course, thanks for the suggestion.

> > The S805 manual, chapter 4 (Memory Map), shows that the DDR memory
> > region start at 0x0 and ends at 0xbfffffff.
> >
> > Following the description of the property "arm,filter-ranges" in Documentation/devicetree/bindings/arm/l2c2x0.txt,
> > which is:
> >
> > - arm,filter-ranges : <start length> Starting address and length of window to
> >   filter. Addresses in the filter window are directed to the M1 port. Other
> >   addresses will go to the M0 port.
> >
> > it seems correct to set the range to <0x0 0xc0000000>, to direct memory accesses
> > on port M1 and other accesses on port M0.
> ok, makes sense so far
> 
> > If I'm wrong, could you please explain why the range used so far is correct ?
> maybe Carlo (who originally brought up that we are missing this
> property) can give some more details why the original value was
> chosen. I think he took it from the Amlogic GPL kernel sources, see
> [0]
> 

Yes, I think so too.

> > From the memory map, that range covers part of the DDR region
> > and part of the APB3 CBUS memory region (0x01000000 + 0xc000000).
> > Is this the intention?
> indeed, this sounds suspicious
> maybe you could put this information in the commit message as well
> 
> I will give your patch a try on a Meson8m2 (very similar to Meson8)
> and Meson8b device this weekend and let you know.
>

Ok, I'll prepare a new patch with more detailed informations
as soon as I receive a feedback from you.

> >> I would like to understand why it's not working for you
> >> (I do not have an Odroid-C1 board myself, but my EC-100 also comes
> >> with a Meson8b SoC and 2GiB RAM and it boots fine there also)
> >>
> >> > Signed-off-by: Emiliano Ingrassia <ingrassia at epigenesys.com>
> >> > ---
> >> >  arch/arm/boot/dts/meson8b.dtsi | 2 +-
> >> >  1 file changed, 1 insertion(+), 1 deletion(-)
> your commit message states that this patch should fix Meson8 and
> Meson8b - that means you'll also have to apply the same change to
> meson8.dtsi
> 

Sorry, the patch is only for the S805 SoC (meson8b) and I'll correct
that information in the new commit.
I don't know the memory maps of the S802 SoC (meson8) and the S812 SoC (meson8m2)
and don't have any manual about those SoCs.
So, I can't guarantee that the same informations can be applied to them.

> >> >
> >> > diff --git a/arch/arm/boot/dts/meson8b.dtsi b/arch/arm/boot/dts/meson8b.dtsi
> >> > index 72e4f425f190..3f0850cf3403 100644
> >> > --- a/arch/arm/boot/dts/meson8b.dtsi
> >> > +++ b/arch/arm/boot/dts/meson8b.dtsi
> >> > @@ -190,7 +190,7 @@
> >> >  &L2 {
> >> >         arm,data-latency = <3 3 3>;
> >> >         arm,tag-latency = <2 2 2>;
> >> > -       arm,filter-ranges = <0x100000 0xc0000000>;
> >> > +       arm,filter-ranges = <0x0 0xc0000000>;
> >> >  };
> >> >
> >> >  &saradc {
> >> > --
> >> > 2.13.2
> >> >
> >> >
> >> > _______________________________________________
> >> > linux-amlogic mailing list
> >> > linux-amlogic at lists.infradead.org
> >> > http://lists.infradead.org/mailman/listinfo/linux-amlogic
> >>
> >> Regards,
> >> Martin
> >>
> >>
> >> [0] https://storage.kernelci.org/mainline/master/v4.13-rc2-11-g25f6a53799d6/arm/multi_v7_defconfig/lab-baylibre-seattle/boot-meson8b-odroidc1.html
> >
> > Best regards,
> >
> > Emiliano
> 
> 
> Regards,
> Martin
> 
> [0] https://github.com/endlessm/linux-meson/blob/c173f4653186870f08dc9131b5d82ef4ab4151e1/arch/arm/boot/dts/meson8b_m201_1G.dts#L44

Regards,

Emiliano