On 11/12/24 19:01, Manivannan Sadhasivam wrote:
On Mon, Oct 28, 2024 at 03:22:56PM +0100, Konrad Dybcio wrote:
Certain firmwares expose exactly what PSCI_SYSTEM_SUSPEND does through
CPU_SUSPEND instead. Inform Linux about that.
Please see the commit messages for a more detailed explanation.
It is still not PSCI_SYSTEM_SUSPEND though...
It *literally* does the same thing on devices where it's exposed.
This is effectively a more educated follow-up to [1].
The ultimate goal is to stop making Linux think that certain states
only concern cores/clusters, and consequently setting
pm_set_suspend/resume_via_firmware(), so that client drivers (such as
NVMe, see related discussion over at [2]) can make informed decisions
about assuming the power state of the device they govern.
If this series gets green light, I'll push a follow-up one that wires
up said sleep state on Qualcomm SoCs across the board.
Sorry. I don't think PSCI is the right place for this. Qcom SoCs have a common
firmware across all segments (mostly),
This ^
so there is no S2R involved and only S2Idle.
is not at all related to this ^, the "so" makes no sense.
(also you're wrong, this *is* S2RAM)
If you use PSCI to implement suspend_via_firmware(), then all the SoCs
making use of the PSCI implementation will have the same behavior. I don't think
we would want that.
This is an issue with the NVMe framework that is totally unrelated to this
change, see below. Also, the code only sets that on targets where such state
exists and is described.
For instance, if a Qcom SoC is used in an android tablet with the same firmware,
then this would allow the NVMe device to be turned off during system suspend all
the time when user presses the lock button. And this will cause NVMe device to
wear out faster. The said approach will work fine for non-android usecases
though.
The NVMe framework doesn't make a distinction between "phone screen off" and
"laptop lid closed & thrown in a bag" on *any* platform. The usecase you're
describing is not supported as of today since nobody *actually* has NVMe on a
phone that also happens to run upstream Linux.
I'm not going to solve imaginary problems.
Besides, userspace already has sysfs to tune device power state knobs. Which
Android uses very extensively on market devices.
Konrad
