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

[kgene@kernel.org (Kukjin Kim)]

Chanho Park wrote:
> 
> Hi,
> 
> On Tue, Jul 14, 2015 at 5:23 PM, Kukjin Kim <kgene@kernel.org> wrote:
> > 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.
> 
> I also agreed it's not a SoC configuration since second
> patch(exynos5422.dtsi -> exynos5422-cpu.dtsi).
> 
> >
> >> >
> >> > 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.
> 
> Actually, I don't want to disturb current dts hierarchy even though it
> looks strange. The common features of exynos5800 and exynos5422 should
> be in the exynos5800.dtsi because they shared many things except the
> cpu order.
> Please consider the exynos5422-cpu.dtsi is just board configurations
> to represent cpu order.
> 
Yeah, strange and it can cause some confusing...but OK, we don't have much
choice at the moment, so applied to support it even we need some re-work
'current dts hierarchy' next time.

Thanks,
Kukjin