On Mon, Dec 16, 2024 at 5:48 PM Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx> wrote: > > On Mon, Dec 16, 2024 at 05:42:30PM +0100, Rafael J. Wysocki wrote: > > On Mon, Dec 16, 2024 at 5:23 PM Christoph Hellwig <hch@xxxxxx> wrote: > > > > > > On Sat, Dec 14, 2024 at 12:00:23PM +0530, Manivannan Sadhasivam wrote: > > > > We need a PM core API that tells the device drivers when it is safe to powerdown > > > > the devices. The usecase here is with PCIe based NVMe devices but the problem is > > > > applicable to other devices as well. > > > > > > Maybe I'm misunderstanding things, but I think the important part is > > > to indicate when a suspend actually MUST put the device into D3. Because > > > doing that should always be safe, but not always optimal. > > > > I'm not aware of any cases when a device must be put into D3cold > > (which I think is what you mean) during system-wide suspend. > > > > Suspend-to-idle on x86 doesn't require this, at least not for > > correctness. I don't think any platforms using DT require it either. > > > > On suspend-to-idle, yes D3Cold doesn't make sense, Why? > but on suspend-to-ram it is pretty much required. Well, I know for a fact that on x86 platforms ACPI S3 does not require putting devices into D3cold in general. Why is it required for NVMe? > That applies to DT as well. Again, why?
