[PATCH 1/5] arm64: dts: Add basic DT to support Spreadtrum's SP9860G

[chunyan.zhang@spreadtrum.com (Chunyan Zhang)]

Hi Sudeep,

On ?,  2? 14, 2017 at 04:44:53?? +0000, Sudeep Holla wrote:
> On Tue, Feb 14, 2017 at 9:19 AM, Chunyan Zhang
> <chunyan.zhang@spreadtrum.com> wrote:
> > From: Orson Zhai <orson.zhai@spreadtrum.com>
> >
> > SC9860G is a 8 cores of A53 SoC with 4G LTE support SoC from Spreadtrum.
> >
> > According to regular hierarchy of sprd dts, whale2.dtsi contains SoC
> > peripherals IP nodes, sc9860.dtsi contains stuff related to ARM core stuff
> > and sp9860g dts is for the board level.
> >
> > Signed-off-by: Orson Zhai <orson.zhai@spreadtrum.com>
> > Signed-off-by: Chunyan Zhang <chunyan.zhang@spreadtrum.com>
> > ---
> >  arch/arm64/boot/dts/sprd/Makefile         |   3 +-
> >  arch/arm64/boot/dts/sprd/sc9860.dtsi      | 534 ++++++++++++++++++++++++++++++
> >  arch/arm64/boot/dts/sprd/sp9860g-1h10.dts |  58 ++++
> >  arch/arm64/boot/dts/sprd/whale2.dtsi      |  66 ++++
> >  4 files changed, 660 insertions(+), 1 deletion(-)
> >  create mode 100644 arch/arm64/boot/dts/sprd/sc9860.dtsi
> >  create mode 100644 arch/arm64/boot/dts/sprd/sp9860g-1h10.dts
> >  create mode 100644 arch/arm64/boot/dts/sprd/whale2.dtsi
> >
> > diff --git a/arch/arm64/boot/dts/sprd/Makefile b/arch/arm64/boot/dts/sprd/Makefile
> > index b658c5e..f0535e6 100644
> > --- a/arch/arm64/boot/dts/sprd/Makefile
> > +++ b/arch/arm64/boot/dts/sprd/Makefile
> > @@ -1,4 +1,5 @@
> > -dtb-$(CONFIG_ARCH_SPRD) += sc9836-openphone.dtb
> > +dtb-$(CONFIG_ARCH_SPRD) += sc9836-openphone.dtb \
> > +                       sp9860g-1h10.dtb
> >
> >  always         := $(dtb-y)
> >  subdir-y       := $(dts-dirs)
> > diff --git a/arch/arm64/boot/dts/sprd/sc9860.dtsi b/arch/arm64/boot/dts/sprd/sc9860.dtsi
> > new file mode 100644
> > index 0000000..604a8c9
> > --- /dev/null
> > +++ b/arch/arm64/boot/dts/sprd/sc9860.dtsi
> > @@ -0,0 +1,534 @@
> 
> [...]
> 
> > +       idle-states{
> > +               entry-method = "arm,psci";
> > +
> > +               CORE_PD: core_pd {
> > +                       compatible = "arm,idle-state";
> > +                       entry-latency-us = <1000>;
> > +                       exit-latency-us = <700>;
> > +                       min-residency-us = <2500>;
> > +                       local-timer-stop;
> > +                       arm,psci-suspend-param = <0x00010002>;
> > +               };
> > +
> > +               CLUSTER_PD: cluster_pd {
> > +                       compatible = "arm,idle-state";
> > +                       entry-latency-us = <1000>;
> > +                       exit-latency-us = <1000>;
> > +                       min-residency-us = <3000>;
> > +                       local-timer-stop;
> > +                       arm,psci-suspend-param = <0x01010003>;
> > +               };
> > +
> > +               DEEP_SLEEP: deep_sleep {
> > +                       compatible = "arm,idle-state";
> > +                       wakeup-latency-us = <0xffffffff>;
> 
> A value > 4294 seconds(i.e >1 hour) seems suspicious.
> Are you working around the firmware issue with high latency value so
> that it's never entered ? Why not remove advertising the state from DT.
>

Haved checked with related colleagues, this node 'deep_sleep' was not for working
around any firmware issue, but was a trick utilization of idle subsystem, and that
was definitely not elegant, the author indeed intendly didn't want CPU entered this
state, I will remove this node therefore.
 
> Can you get me the dump of:
> grep "" /sys/devices/system/cpu/cpu*/cpuidle/state*/{time,usage}
> 

FYI: https://www.irccloud.com/pastebin/XyEMLzfq/

Thanks,
Chunyan

> IIUC, you might have seen boot issue without this values and workaround
> the issue with such high values ? If so please drop this state.
> 
> > +                       entry-latency-us = <1500>;
> > +                       exit-latency-us = <1500>;
> > +                       min-residency-us = <0xffffffff>;
> > +                       local-timer-stop;
> > +                       arm,psci-suspend-param = <0x01010005>;
> > +               };
> > +       };
> >
> 
> --
> Regards,
> Sudeep