[PATCHv6] ARM: dts: add exynos5422-cpus.dtsi to correct cpu order

[kgene@kernel.org (Kukjin Kim)]

Chanho Park wrote:
> 
> Hi Kukjin,
> 
> On Tue, Jul 14, 2015 at 2:04 PM, Kukjin Kim <kgene@kernel.org> wrote:
> > Krzysztof Kozlowski wrote:
> >>
> >> On 14.07.2015 09:24, Chanho Park wrote:
> >> > The odroid-xu3 board which is based on exynos5422 not exynos5800 is
> >> > booted from cortex-a7 core unlike exynos5800. The odroid-xu3's cpu order
> >> > is quite strange. cpu0 and cpu5-7 are cortex-a7 cores and cpu1-4 are
> >> > cortex-a15 cores. To correct this mis-odering, I added exynos5422-cpus.dtsi
> >> > and reversing cpu orders from exynos5420. Now, cpu0-3 are cortex-a7 and
> >> > cpu4-7 are cortex-a15.
> >> >
> >> > Reviewed-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
> >> > Signed-off-by: Chanho Park <parkch98@gmail.com>
> >> > ---

[...]

> >> >
> >> > Secondary cpu booting problem[1] is not resolved yet. Need more investigations
> >> > to work booting 8 cores correctly.
> >> >
> >> > [1]: http://www.spinics.net/lists/linux-samsung-soc/msg45525.html
> >> >
> >> >  arch/arm/boot/dts/exynos5422-cpus.dtsi             | 81 ++++++++++++++++++++++
> >> >  arch/arm/boot/dts/exynos5422-odroidxu3-common.dtsi |  1 +
> >> >  2 files changed, 82 insertions(+)
> >> >  create mode 100644 arch/arm/boot/dts/exynos5422-cpus.dtsi
> >>
> >> Thanks, applied to my tree. I'll send it to Kukjin for v4.3 unless he
> >> picks it also.
> >>
> > Well, let me see. I'm thinking we need to sort out the cpu ordering and dtsi
> > inclusions for exynos5420, 5422 and 5800 related to DT files.
> >
> > See,
> >
> > 1) exynos5420 DT (cpu0~3: a15, cpu 4~7: a7)
> > 2) exynos5800 DT is including exynos5420 DT
> > 3) exynos5422 and exynos5800 based boards are including exynos5800 DT.
> >
> > Then making exynos5422-cpus DT for exynos5422 based boards?
> > (cpu0~3: a7, cpu4~7: a15)
> >
> > I think, it could cause confusion when new board based on them are added
> > because it's not clear and the boot cpu could be selected by bootloader part.
> 
> The iROM will check the GPIO pin to select which core is run as cpu0.
> I think no one will change the GPIO pin if a new board which is based
> on exynos5422 :)
> 
Yes, I know the boot sequence and it means it depends on board configuration
not SoC. That?s why I'm saying it should be handled in board DT file. I think,
most of current exynos big.LITTLE model should do if it could be changed
according to board configuration.

> >
> > So how about creating exynos5422-cpus and exynos5420-cpus then including the
> > cpus DT file in each board accordingly?
> >
> > Or more clear way to avoid confusion?
> 
> In this situation, all exynos5422 boards(odroid xu3 series and mobile
> phone) have same cpu configurations. If we move the exynos5420 cpu
> configuration from exynos5420.dtsi, we should change all dts which
> including exynos5420.dtsi.

Maybe same board configuration. Just adding inclusion should be fine at this
moment.

> I think we'd better to defer the change until a new exynos5422 board
> which has different cpu configurations is added.
> 
I mean, according to current inclusion of exynos5422 based boards' DT file, it
is including exynos5420 DT via exynos5800 DT and then override different cpu
ordering (5422-cpu DT) because of different board configuration (just GPIO
value) and it is not a good way in this case.

- Kukjin