On Thu, Dec 19, 2024 at 08:43:27PM +0100, Konrad Dybcio wrote: > On 6.12.2024 11:21 AM, Sudeep Holla wrote: > > On Mon, Oct 28, 2024 at 03:22:57PM +0100, Konrad Dybcio wrote: > >> From: Konrad Dybcio <konrad.dybcio@xxxxxxxxxxxxxxxx> > >> > >> Certain firmware implementations (such as the ones found on Qualcomm > >> SoCs between roughly 2015 and 2023) expose an S3-like S2RAM state > >> through the CPU_SUSPEND call, as opposed to exposing PSCIv1.0's > >> optional PSCI_SYSTEM_SUSPEND. > >> > > > > If so, can you elaborate why s2idle doesn't work as an alternative to what > > you are hacking up here. > > Please see other branches of this thread > > > > >> This really doesn't work well with the model where we associate all > >> calls to CPU_SUSPEND with cpuidle. Allow specifying a single special > >> CPU_SUSPEND suspend parameter value that is to be treated just like > >> SYSTEM_SUSPEND from the OS's point of view. > >> > >> Signed-off-by: Konrad Dybcio <konrad.dybcio@xxxxxxxxxxxxxxxx> > >> --- > >> Documentation/devicetree/bindings/arm/psci.yaml | 6 ++++++ > >> 1 file changed, 6 insertions(+) > >> > >> diff --git a/Documentation/devicetree/bindings/arm/psci.yaml b/Documentation/devicetree/bindings/arm/psci.yaml > >> index cbb012e217ab80c1ca88e611e7acc06c6d56fad0..a6901878697c8e1ec1cbfed62298ae3bc58f2501 100644 > >> --- a/Documentation/devicetree/bindings/arm/psci.yaml > >> +++ b/Documentation/devicetree/bindings/arm/psci.yaml > >> @@ -98,6 +98,12 @@ properties: > >> [1] Kernel documentation - ARM idle states bindings > >> Documentation/devicetree/bindings/cpu/idle-states.yaml > >> > >> + arm,psci-s2ram-param: > >> + $ref: /schemas/types.yaml#/definitions/uint32 > >> + description: > >> + power_state parameter denoting the S2RAM/S3-like system suspend state > > > > Yet another NACK as this corresponds to PSCI SYSTEM_SUSPEND and as per > > specification it takes no such parameter. This is just misleading. > > > > Yeah PSCI_SYSTEM_SUSPEND takes care of this on platforms that expose it. > And those that don't advertise/expose don't get to use, simple. > DEN0022F.b Section 6.5. recommends that CPU_SUSPEND StateID includes > a field for system-level power down states. This binding change only > adds a way for DT-based platforms to associate such state with S2RAM > suspend. > Sure, just use the CPU_SUSPEND bindings that already exist. No need to define this as some special case if it is exposed as CPU_SUSPEND idle state. Not sure why you want to do it differently. I understand the need to handle it different in the kernel, but I don't understand to define the new bindings for that. Just use the existing bindings for the idle states. Again I see no exception for this case. > That may be a bit Linux-specific whereas bindings are supposed to be > OS-agnostic, but since we effectively want one PSCI state for deep > suspend regardless of the OS, I would think this kind of hint is fine. > Exactly, that's the reason for not changing this into special case and special binding for that special case created. -- Regards, Sudeep
