From: Todd Poynor Currently all devices are resumed at system resume time, including any that were individually powered off ("at runtime") prior to the system suspend. In certain cases it can be nice to force back on individually suspended devices, such as the display, but hopefully this policy can be left up to userspace power managers; the kernel should probably honor the settings previously made by userspace/drivers. This seems preferable to requiring a power-conscious system to re-suspend devices after a system resume; furthermore, for certain platforms (such as XScale PXA27X) there can be disastrous consequences of powering up devices when the system is in a state incompatible with operation of the device. Suggested patch does this: (1) At system resume, checks power_state to see if the device was suspended prior to system suspend, and skips powering on the device if so. (2) Does not re-suspend an already-suspended device at system suspend (using a different method than is currently employed, which reorders the list, see #3). (3) Preserves the active/off device list order despite the above changes to suspend/resume behavior, to avoid dependency problems that tend to occur when the list is reordered. Signed-off-by: Andrew Morton --- 25-akpm/drivers/base/power/resume.c | 5 ++++- 25-akpm/drivers/base/power/suspend.c | 2 +- 2 files changed, 5 insertions(+), 2 deletions(-) diff -puN drivers/base/power/resume.c~leave-runtime-suspended-devices-off-at-system-resume drivers/base/power/resume.c --- 25/drivers/base/power/resume.c~leave-runtime-suspended-devices-off-at-system-resume 2004-05-26 20:56:09.315676672 -0700 +++ 25-akpm/drivers/base/power/resume.c 2004-05-26 20:56:09.320675912 -0700 @@ -35,7 +35,10 @@ void dpm_resume(void) struct list_head * entry = dpm_off.next; struct device * dev = to_device(entry); list_del_init(entry); - resume_device(dev); + + if (!dev->power.power_state) + resume_device(dev); + list_add_tail(entry,&dpm_active); } } diff -puN drivers/base/power/suspend.c~leave-runtime-suspended-devices-off-at-system-resume drivers/base/power/suspend.c --- 25/drivers/base/power/suspend.c~leave-runtime-suspended-devices-off-at-system-resume 2004-05-26 20:56:09.316676520 -0700 +++ 25-akpm/drivers/base/power/suspend.c 2004-05-26 20:56:09.319676064 -0700 @@ -39,7 +39,7 @@ int suspend_device(struct device * dev, { int error = 0; - if (dev->bus && dev->bus->suspend) + if (dev->bus && dev->bus->suspend && !dev->power.power_state) error = dev->bus->suspend(dev,state); return error; _