On 8/17/2023 2:25 PM, Bjorn Helgaas wrote:
On Wed, Aug 16, 2023 at 03:41:43PM -0500, Mario Limonciello wrote:
Since commit 9d26d3a8f1b0 ("PCI: Put PCIe ports into D3 during suspend")
PCIe ports from modern machines (>=2015) are allowed to be put into D3 by
storing a value to the `bridge_d3` variable in the `struct pci_dev`
structure.
...
+static void lpi_check_pci_dev(struct lpi_constraints *entry, struct pci_dev *pdev)
+{
+ pci_power_t target = entry->enabled ? entry->min_dstate : PCI_D0;
+
+ if (pdev->current_state == target)
+ return;
+
+ /* constraint of ACPI D3hot means PCI D3hot _or_ D3cold */
+ if (target == ACPI_STATE_D3_HOT &&
ACPI_STATE_D3_HOT is not a valid pci_power_t value.
Based on this, kernel robot sparse complaints and your comments on v11's
last patch I am going to split off to another function that returns the
pci_power_t state based upon the situation and better comment the reason
for the D0 when not enabled.
+ (pdev->current_state == PCI_D3hot ||
+ pdev->current_state == PCI_D3cold))
+ return;
+
+ if (pm_debug_messages_on)
+ acpi_handle_info(entry->handle,
+ "LPI: PCI device in %s, not in %s\n",
+ acpi_power_state_string(pdev->current_state),
+ acpi_power_state_string(target));
+
+ /* don't try with things that PCI core hasn't touched */
+ if (pdev->current_state == PCI_UNKNOWN) {
+ entry->handle = NULL;
+ return;
+ }
+
+ pci_set_power_state(pdev, target);
It doesn't seem logical for a "check_constraints()" function that
takes no parameters and returns nothing to actively set the PCI power
state.
lpi_check_constraints() returns nothing, and from the fact that it was
previously only called when "pm_debug_messages_on", I infer that it
should have no side effects.
IMHO "lpi_check_constraints" is not a great name because "check"
doesn't suggest anything specific about what it does.
"dump_constraints()" -- fine. "log_unmet_constraints()" -- fine
(seems like the original intention of 726fb6b4f2a8 ("ACPI / PM: Check
low power idle constraints for debug only"), which added it.
Great feedback, thanks. I'm thinking to instead change it to:
lpi_enforce_constraints()
+}
+
static void lpi_check_constraints(void)
{
struct lpi_constraints *entry;
for_each_lpi_constraint(entry) {
struct acpi_device *adev = acpi_fetch_acpi_dev(entry->handle);
+ struct device *dev;
if (!adev)
continue;
+ /* Check and adjust PCI devices explicitly */
+ dev = acpi_get_first_physical_node(adev);
+ if (dev && dev_is_pci(dev)) {
+ lpi_check_pci_dev(entry, to_pci_dev(dev));
+ continue;
+ }
+ if (!entry->enabled)
+ continue;
acpi_handle_debug(entry->handle,
"LPI: required min power state:%s current power state:%s\n",
acpi_power_state_string(entry->min_dstate),
acpi_power_state_string(adev->power.state));
- if (!adev->flags.power_manageable) {
- acpi_handle_info(entry->handle, "LPI: Device not power manageable\n");
- entry->handle = NULL;
- continue;
- }
-
- if (adev->power.state < entry->min_dstate)
+ if (pm_debug_messages_on &&
+ adev->flags.power_manageable &&
+ adev->power.state < entry->min_dstate)
acpi_handle_info(entry->handle,
"LPI: Constraint not met; min power state:%s current power state:%s\n",
acpi_power_state_string(entry->min_dstate),
@@ -512,8 +546,7 @@ int acpi_s2idle_prepare_late(void)
if (!lps0_device_handle || sleep_no_lps0)
return 0;
- if (pm_debug_messages_on)
- lpi_check_constraints();
+ lpi_check_constraints();
/* Screen off */
if (lps0_dsm_func_mask > 0)
--
2.34.1
