On 8/21/2023 2:24 PM, Rafael J. Wysocki wrote:
On Mon, Aug 21, 2023 at 9:18 PM Limonciello, Mario
<mario.limonciello@xxxxxxx> wrote:
On 8/21/2023 1:46 PM, Rafael J. Wysocki wrote:
On Fri, Aug 18, 2023 at 9:40 PM Mario Limonciello
<mario.limonciello@xxxxxxx> wrote:
Intel systems that need to have PCIe ports in D3 for low power idle
specify this by constraints on the ACPI PNP0D80 device. As this information
is queried by acpi_pci_bridge_d3(), limit the DMI BIOS year check to stop
at 2024. This will allow future systems to rely on the constraints check
and ACPI checks to set up policy like non-Intel systems do.
So I'm not sure about the value of this change.
The behavior is made Intel-specific in [14a 1/1] and it will be that
way at least for some time. This change only sets the date after
which it won't be Intel-specific any more, but for what reason
exactly?
And why is 2024 the cut-off year (and not 2025, for example)?
No particular reason other than it's a few kernel cycles to get this
tested and working or revert it if it's a bad idea after all.
If Intel platforms continue to be OK with putting all PCIe ports into
D3hot beyond 2024, why restrict the kernel from doing so on them?
OK let me try to explain my thought process.
The reason that root ports were put into D3 on Intel systems was that
it's required for the system to get into the deepest state.
At the time that it was introduced there wasn't a way for the firmware
to express this desire for root ports that were not power manageable by
ACPI.
Constraints are a good way to express it, so by limiting the Intel
hardcode to a number of years gets everyone onto the same codepaths.
Assuming that the will be used in future systems, but that is beyond
the control of anyone involved here I think.
But that being said - if you would rather keep Intel as hardcode forever
this patch can be dropped from the series.
This change can be made at any time and I don't see a particular
reason for making it right now.
OK, then after Bjorn reviews the other patches of 14.a and 14.c I'll
drop this patch.
Thanks!
