[U-Boot] [PATCH 4/5] arm: Provide common PSCI based reset handler

[Simon Glass]

Hi Alex,

On 17 August 2016 at 22:00, Alexander Graf <agraf at suse.de> wrote:
>
>
>> Am 18.08.2016 um 05:44 schrieb Simon Glass <sjg at chromium.org>:
>>
>> Hi Alex,
>>
>>> On 16 August 2016 at 13:08, Alexander Graf <agraf at suse.de> wrote:
>>> Most armv8 systems have PSCI support enabled in EL3, either through
>>> ARM Trusted Firmware or other firmware.
>>>
>>> On these systems, we do not need to implement system reset manually,
>>> but can instead rely on higher level firmware to deal with it.
>>>
>>> The exclude list seems excessive right now, but NXP is working on
>>> providing an in-tree PSCI implementation, so that all NXP systems
>>> can eventually use PSCI as well.
>>>
>>> Signed-off-by: Alexander Graf <agraf at suse.de>
>>> ---
>>> arch/arm/cpu/armv8/Kconfig   | 18 ++++++++++++++++++
>>> arch/arm/cpu/armv8/fwcall.c  |  7 +++++++
>>> arch/arm/mach-meson/board.c  |  5 -----
>>> board/xilinx/zynqmp/zynqmp.c |  5 -----
>>> 4 files changed, 25 insertions(+), 10 deletions(-)
>>
>> Reviewed-by: Simon Glass <sjg at chromium.org>
>>
>>>
>>> diff --git a/arch/arm/cpu/armv8/Kconfig b/arch/arm/cpu/armv8/Kconfig
>>> index 7e1fc4c..cd2d9bb 100644
>>> --- a/arch/arm/cpu/armv8/Kconfig
>>> +++ b/arch/arm/cpu/armv8/Kconfig
>>> @@ -21,4 +21,22 @@ config ARMV8_SPIN_TABLE
>>>            - Reserve the code for the spin-table and the release address
>>>              via a /memreserve/ region in the Device Tree.
>>>
>>> +config PSCI_RESET
>>> +       bool "Use PSCI for reset and shutdown"
>>> +       default y
>>> +       depends on !ARCH_EXYNOS7 && !ARCH_BCM283X && !TARGET_LS2080A_EMU && \
>>> +                  !TARGET_LS2080A_SIMU && !TARGET_LS2080AQDS && \
>>> +                  !TARGET_LS2080ARDB && !TARGET_LS1012AQDS && \
>>> +                  !TARGET_LS1012ARDB && !TARGET_LS1012AFRDM && \
>>> +                  !TARGET_LS1043ARDB && !ARCH_UNIPHIER && !ARCH_SNAPDRAGON && \
>>> +                  !TARGET_S32V234EVB
>>
>> Will this break new systems that are added?
>
> I would word it differently - it will gently push new systems into the right direction ;). With PSCI available, Linux SMP will "just work" too.
>
> The worst that can happen is that someone enables a nee system which does not provide PSCI. In that case we have non-working reboot and shutdown handlers. The alternative would be no reboot and shutdown handlers (which is a fatal panic on Linux for example), so we're not worse off imho.

Sounds good.

Regards,
Simon