| Message ID | 13388608.OHKVb9tm6R@kreacher (mailing list archive) |
|---|---|
| State | Mainlined, archived |
| Headers | show |
| Series | ACPI: PM: Avoid using power resources if there are none for D0 | expand |
Hi, On 6/4/20 7:22 PM, Rafael J. Wysocki wrote: > From: Rafael J. Wysocki <rafael.j.wysocki@intel.com> > > As recently reported, some platforms provide a list of power > resources for device power state D3hot, through the _PR3 object, > but they do not provide a list of power resources for device power > state D0. > > Among other things, this causes acpi_device_get_power() to return > D3hot as the current state of the device in question if all of the > D3hot power resources are "on", because it sees the power_resources > flag set and calls acpi_power_get_inferred_state() which finds that > D3hot is the shallowest power state with all of the associated power > resources turned "on", so that's what it returns. Moreover, that > value takes precedence over the acpi_dev_pm_explicit_get() return > value, because it means a deeper power state. The device may very > well be in D0 physically at that point, however. > > Moreover, the presence of _PR3 without _PR0 for a given device > means that only one D3-level power state can be supported by it. > Namely, because there are no power resources to turn "off" when > transitioning the device from D0 into D3cold (which should be > supported since _PR3 is present), the evaluation of _PS3 should > be sufficient to put it straight into D3cold, but this means that > the effect of turning "on" the _PR3 power resources is unclear, > so it is better to avoid doing that altogether. Consequently, > there is no practical way do distinguish D3cold from D3hot for > the device in question and the power states of it can be labeled > so that D3hot is the deepest supported one (and Linux assumes > that putting a device into D3hot via ACPI may cause power to be > removed from it anyway, for legacy reasons). > > To work around the problem described above modify the ACPI > enumeration of devices so that power resources are only used > for device power management if the list of D0 power resources > is not empty and make it mart D3cold as supported only if that > is the case and the D3hot list of power resources is not empty > too. > > Fixes: ef85bdbec444 ("ACPI / scan: Consolidate extraction of power resources lists") > Link: https://bugzilla.kernel.org/show_bug.cgi?id=205057 > Link: https://lore.kernel.org/linux-acpi/20200603194659.185757-1-hdegoede@redhat.com/ > Reported-by: Hans de Goede <hdegoede@redhat.com> > Cc: 3.10+ <stable@vger.kernel.org> # 3.10+ > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Thank you. I've tested this and I can confirm that it fixes the issue: Tested-by: Hans de Goede <hdegoede@redhat.com> I've also looked at the code and it looks good to me: Reviewed-by: Hans de Goede <hdegoede@redhat.com> Regards, Hans > --- > drivers/acpi/device_pm.c | 2 +- > drivers/acpi/scan.c | 28 +++++++++++++++++++--------- > 2 files changed, 20 insertions(+), 10 deletions(-) > > Index: linux-pm/drivers/acpi/scan.c > =================================================================== > --- linux-pm.orig/drivers/acpi/scan.c > +++ linux-pm/drivers/acpi/scan.c > @@ -919,12 +919,9 @@ static void acpi_bus_init_power_state(st > > if (buffer.length && package > && package->type == ACPI_TYPE_PACKAGE > - && package->package.count) { > - int err = acpi_extract_power_resources(package, 0, > - &ps->resources); > - if (!err) > - device->power.flags.power_resources = 1; > - } > + && package->package.count) > + acpi_extract_power_resources(package, 0, &ps->resources); > + > ACPI_FREE(buffer.pointer); > } > > @@ -971,14 +968,27 @@ static void acpi_bus_get_power_flags(str > acpi_bus_init_power_state(device, i); > > INIT_LIST_HEAD(&device->power.states[ACPI_STATE_D3_COLD].resources); > - if (!list_empty(&device->power.states[ACPI_STATE_D3_HOT].resources)) > - device->power.states[ACPI_STATE_D3_COLD].flags.valid = 1; > > - /* Set defaults for D0 and D3hot states (always valid) */ > + /* Set the defaults for D0 and D3hot (always supported). */ > device->power.states[ACPI_STATE_D0].flags.valid = 1; > device->power.states[ACPI_STATE_D0].power = 100; > device->power.states[ACPI_STATE_D3_HOT].flags.valid = 1; > > + /* > + * Use power resources only if the D0 list of them is populated, because > + * some platforms may provide _PR3 only to indicate D3cold support and > + * in those cases the power resources list returned by it may be bogus. > + */ > + if (!list_empty(&device->power.states[ACPI_STATE_D0].resources)) { > + device->power.flags.power_resources = 1; > + /* > + * D3cold is supported if the D3hot list of power resources is > + * not empty. > + */ > + if (!list_empty(&device->power.states[ACPI_STATE_D3_HOT].resources)) > + device->power.states[ACPI_STATE_D3_COLD].flags.valid = 1; > + } > + > if (acpi_bus_init_power(device)) > device->flags.power_manageable = 0; > } > Index: linux-pm/drivers/acpi/device_pm.c > =================================================================== > --- linux-pm.orig/drivers/acpi/device_pm.c > +++ linux-pm/drivers/acpi/device_pm.c > @@ -186,7 +186,7 @@ int acpi_device_set_power(struct acpi_de > * possibly drop references to the power resources in use. > */ > state = ACPI_STATE_D3_HOT; > - /* If _PR3 is not available, use D3hot as the target state. */ > + /* If D3cold is not supported, use D3hot as the target state. */ > if (!device->power.states[ACPI_STATE_D3_COLD].flags.valid) > target_state = state; > } else if (!device->power.states[state].flags.valid) { > > >
Index: linux-pm/drivers/acpi/scan.c =================================================================== --- linux-pm.orig/drivers/acpi/scan.c +++ linux-pm/drivers/acpi/scan.c @@ -919,12 +919,9 @@ static void acpi_bus_init_power_state(st if (buffer.length && package && package->type == ACPI_TYPE_PACKAGE - && package->package.count) { - int err = acpi_extract_power_resources(package, 0, - &ps->resources); - if (!err) - device->power.flags.power_resources = 1; - } + && package->package.count) + acpi_extract_power_resources(package, 0, &ps->resources); + ACPI_FREE(buffer.pointer); } @@ -971,14 +968,27 @@ static void acpi_bus_get_power_flags(str acpi_bus_init_power_state(device, i); INIT_LIST_HEAD(&device->power.states[ACPI_STATE_D3_COLD].resources); - if (!list_empty(&device->power.states[ACPI_STATE_D3_HOT].resources)) - device->power.states[ACPI_STATE_D3_COLD].flags.valid = 1; - /* Set defaults for D0 and D3hot states (always valid) */ + /* Set the defaults for D0 and D3hot (always supported). */ device->power.states[ACPI_STATE_D0].flags.valid = 1; device->power.states[ACPI_STATE_D0].power = 100; device->power.states[ACPI_STATE_D3_HOT].flags.valid = 1; + /* + * Use power resources only if the D0 list of them is populated, because + * some platforms may provide _PR3 only to indicate D3cold support and + * in those cases the power resources list returned by it may be bogus. + */ + if (!list_empty(&device->power.states[ACPI_STATE_D0].resources)) { + device->power.flags.power_resources = 1; + /* + * D3cold is supported if the D3hot list of power resources is + * not empty. + */ + if (!list_empty(&device->power.states[ACPI_STATE_D3_HOT].resources)) + device->power.states[ACPI_STATE_D3_COLD].flags.valid = 1; + } + if (acpi_bus_init_power(device)) device->flags.power_manageable = 0; } Index: linux-pm/drivers/acpi/device_pm.c =================================================================== --- linux-pm.orig/drivers/acpi/device_pm.c +++ linux-pm/drivers/acpi/device_pm.c @@ -186,7 +186,7 @@ int acpi_device_set_power(struct acpi_de * possibly drop references to the power resources in use. */ state = ACPI_STATE_D3_HOT; - /* If _PR3 is not available, use D3hot as the target state. */ + /* If D3cold is not supported, use D3hot as the target state. */ if (!device->power.states[ACPI_STATE_D3_COLD].flags.valid) target_state = state; } else if (!device->power.states[state].flags.valid) {