Linux Patches Updated To Fix Latest Suspend/Resume Issues For Some AMD Laptops
On the AMD laptop side under Linux in recent kernels there's been improvements to S0ix support and a variety of different suspend/resume issues being resolved. The latest patch series is a revision of work aiming to deal with wake-up problems affecting some AMD platforms.
Mario Limonciello of AMD's Linux client team explained in the updated patch series of these latest suspend/resume woes:
Problems have been reported on AMD laptops with suspend/resume where particular root ports are put into D3 and then the system is unable to resume properly.
The issue boils down to the currently selected kernel policy for root port behavior at suspend time:
0) If the machine is from 2015 or later
1) If a PCIe root port is power manageable by the platform then platform will be used to determine the power state of the root port at suspend.
2) If the PCIe root is not power manageable by the platform then the kernel will check if it was configured to wakeup.
3) If it was, then it will be put into the deepest state that supports wakeup from PME.
4) If it wasn't, then it will be put into D3hot.
This patch adjusts it so that device constraints for low power idle are considered instead of a time based policy.
With the updated behavior to use device constraints rather than the arbitrary dates to opt devices into D3, it fixes waking up from some newer AMD Ryzen laptops.
This is reported to fix an issue at least known on the Lenovo Z13 where it can't resume from suspend with an external USB keyboard attached. Other USB devices attached also cause issues when trying to wake-up the system. Other platforms are likely affected too.
But at the moment there is some concern potentially regressing some yet to be identified Intel systems, so we'll see how much longer it takes this work to bake before being mainlined. In any event, AMD Linux engineers continue the effort of squashing various suspend/resume issues for Ryzen laptops.
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