[PATCH 2/2] ARM: bcm2835: Add devicetree for the Raspberry Pi 3.

Mark Rutland
2016-03-04T18:59:24Z

On Fri, Mar 04, 2016 at 10:55:03AM -0800, Eric Anholt wrote:
> Mark Rutland <mark.rutland@arm.com> writes:
>
> > On Fri, Mar 04, 2016 at 10:39:29AM -0800, Eric Anholt wrote:
> >> For now this doesn't support the new hardware present on the Pi 3 (BT,
> >> wifi, GPIO expander). Since the GPIO expander isn't supported, we
> >> also don't have the LEDs like the other board files do.
> >>
> >> Signed-off-by: Eric Anholt <eric@anholt.net>
> >> ---
> >> arch/arm/boot/dts/Makefile | 3 +-
> >> arch/arm/boot/dts/bcm2837-rpi-3-b.dts | 22 ++++++++++++
> >> arch/arm/boot/dts/bcm2837.dtsi | 68 +++++++++++++++++++++++++++++++++++
> >> 3 files changed, 92 insertions(+), 1 deletion(-)
> >> create mode 100644 arch/arm/boot/dts/bcm2837-rpi-3-b.dts
> >> create mode 100644 arch/arm/boot/dts/bcm2837.dtsi
> >
> >> + timer {
> >> + compatible = "arm,armv7-timer";
> >> + interrupt-parent = <&local_intc>;
> >> + interrupts = <0>, // PHYS_SECURE_PPI
> >> + <1>, // PHYS_NONSECURE_PPI
> >> + <3>, // VIRT_PPI
> >> + <2>; // HYP_PPI
> >> + always-on;
> >> + };
> >
> > Are the CPUs in an always-on power domain? Or is it jsut that the kernel
> > doesn't perform power management of CPUs?
> >
> > The always-on proeprty is only intended for the former.
>
> The kernel doesn't get to do power management of CPUs. We only have
> control of power domains through the firmware, and the firmware's
> keeping the CPU domain on.

So there is no way that the CPUs could request for the firmare to place
them in a state where the timer would lose context (but other events
coukd wake them up), even if they don't do that today?

Mark