From e78adb7595a9d585c60a7497345cb6eaeaaacefb Mon Sep 17 00:00:00 2001 From: "Rafael J. Wysocki" Date: Tue, 22 Jan 2013 12:56:04 +0100 Subject: [PATCH] ACPI / PM: Always evaluate _PSn after setting power resources The ACPI specitication (ACPI 5, Sections 7.2.8 - 7.2.11) requires that the _PSn (n = 0..3) method, if present, be executed after the power resources for the given device power state have been set appropriately. However, acpi_device_set_power() does that only if the new power state is going to be higher-power (lower-number) than the power state the device is in already. Otherwise, the ordering is reverse to protect against situations in which _PSn might access device registers unavailable after configuring the power resources for power state Dn (D3 meaning D3hot). Such situations are very unlikely to happen, though, and _PSn may actually be implemented with the assumption that power resources have been configured for power state Dn in advance, so change the code to follow the specification literally. This change was previously porposed in a different form by Lv Zheng. Signed-off-by: Rafael J. Wysocki --- drivers/acpi/device_pm.c | 46 +++++++++++++++------------------------- 1 file changed, 17 insertions(+), 29 deletions(-) diff --git a/drivers/acpi/device_pm.c b/drivers/acpi/device_pm.c index d7f3908c2e88..2ce07cee0434 100644 --- a/drivers/acpi/device_pm.c +++ b/drivers/acpi/device_pm.c @@ -242,50 +242,38 @@ int acpi_device_set_power(struct acpi_device *device, int state) cut_power = true; } + if (state < device->power.state && state != ACPI_STATE_D0 + && device->power.state >= ACPI_STATE_D3_HOT) { + printk(KERN_WARNING PREFIX + "Cannot transition to non-D0 state from D3\n"); + return -ENODEV; + } + /* * Transition Power * ---------------- - * On transitions to a high-powered state we first apply power (via - * power resources) then evalute _PSx. Conversly for transitions to - * a lower-powered state. + * In accordance with the ACPI specification first apply power (via + * power resources) and then evalute _PSx. */ - if (state < device->power.state) { - if (device->power.state >= ACPI_STATE_D3_HOT && - state != ACPI_STATE_D0) { - printk(KERN_WARNING PREFIX - "Cannot transition to non-D0 state from D3\n"); - return -ENODEV; - } - if (device->power.flags.power_resources) { - result = acpi_power_transition(device, state); - if (result) - goto end; - } - result = acpi_dev_pm_explicit_set(device, state); + if (device->power.flags.power_resources) { + result = acpi_power_transition(device, state); if (result) goto end; - } else { - result = acpi_dev_pm_explicit_set(device, state); - if (result) - goto end; - - if (device->power.flags.power_resources) { - result = acpi_power_transition(device, state); - if (result) - goto end; - } } + result = acpi_dev_pm_explicit_set(device, state); + if (result) + goto end; if (cut_power) result = acpi_power_transition(device, ACPI_STATE_D3_COLD); - end: - if (result) + end: + if (result) { printk(KERN_WARNING PREFIX "Device [%s] failed to transition to %s\n", device->pnp.bus_id, acpi_power_state_string(state)); - else { + } else { device->power.state = state; ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Device [%s] transitioned to %s\n", -- 2.20.1