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SubjectRe: [PATCH v2] firmware/psci: add support for SYSTEM_RESET2
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On 09/07/18 14:13, Michal Simek wrote:
> On 9.7.2018 14:36, Sudeep Holla wrote:
>>
>>
>> On 09/07/18 13:17, Michal Simek wrote:
>>> Hi Sudeep,
>>>
>>> On 2.5.2018 12:30, Sudeep Holla wrote:
>>>> PSCI v1.1 introduced SYSTEM_RESET2 to allow both architectural resets
>>>> where the semantics are described by the PSCI specification itself as
>>>> well as vendor-specific resets. Currently only system warm reset
>>>> semantics is defined as part of architectural resets by the specification.
>>>>
>>>> This patch implements support for SYSTEM_RESET2 by making using of
>>>> reboot_mode passed by the reboot infrastructure in the kernel.
>>>>
>>>> Cc: Mark Rutland <mark.rutland@arm.com>
>>>> Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
>>>> Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
>>>> ---
>>>> drivers/firmware/psci.c | 21 +++++++++++++++++++++
>>>> include/uapi/linux/psci.h | 2 ++
>>>> 2 files changed, 23 insertions(+)
>>>>
>>>> v1->v2:
>>>> - Added mising static anotation to psci_system_reset2_supported
>>>> - Added missing ')' in the comment
>>>>
>>>> diff --git a/drivers/firmware/psci.c b/drivers/firmware/psci.c
>>>> index c80ec1d03274..91748725534e 100644
>>>> --- a/drivers/firmware/psci.c
>>>> +++ b/drivers/firmware/psci.c
>>>> @@ -88,6 +88,7 @@ static u32 psci_function_id[PSCI_FN_MAX];
>>>> PSCI_1_0_EXT_POWER_STATE_TYPE_MASK)
>>>>
>>>> static u32 psci_cpu_suspend_feature;
>>>> +static bool psci_system_reset2_supported;
>>>>
>>>> static inline bool psci_has_ext_power_state(void)
>>>> {
>>>> @@ -253,6 +254,15 @@ static int get_set_conduit_method(struct device_node *np)
>>>>
>>>> static void psci_sys_reset(enum reboot_mode reboot_mode, const char *cmd)
>>>> {
>>>> + if ((reboot_mode == REBOOT_WARM || reboot_mode == REBOOT_SOFT) &&
>>>
>>> I am curious about this reboot_mode setup. I have grepped the kernel and
>>> reboot_mode is setup via kernel parameters at boot time.
>>> Shouldn't user decide what reboot type wants to do?
>>>
>>
>> I have almost forgotten how I tested this. IIRC and looking quickly @
>> kernel/reboot.c and __setup(reboot=,...), I recall passing reboot=w
>> while testing this.
>
> I would expect that too. It means static setting at boot time.
>
>> We can do something like what efi_reboot, but not
>> sure if we need that yet if users need too decide after boot.
>
>
> I am checking with colleague about all xilinx use cases but I would be
> surprised if static configuration at run time is enough.
>
> Also not quite sure about mixing reboot_warm and reboot_soft cases
> together. They shouldn't be the same.
>
> Based on psci 1.0 spec there are more options especially for bit[31]
> which should be likely setup via DT(no experience with EFI) with names
> and codes which should be passed to firmware but still the same issue
> remains how to setup reboot type.
>

I think with efi_reboot, if user execute the command "reboot warm", it
will set REBOOT_WARM. I was thinking something similar for psci too. I
can drop REBOOT_SOFT if that's not correct.

--
Regards,
Sudeep

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