ChangeSet 1.1717.7.5, 2004/05/28 10:04:44-07:00, tpoynor@mvista.com [PATCH] Leave runtime suspended devices off at system resume 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: Greg Kroah-Hartman drivers/base/power/resume.c | 5 ++++- drivers/base/power/suspend.c | 2 +- 2 files changed, 5 insertions(+), 2 deletions(-) diff -Nru a/drivers/base/power/resume.c b/drivers/base/power/resume.c --- a/drivers/base/power/resume.c Fri May 28 14:18:10 2004 +++ b/drivers/base/power/resume.c Fri May 28 14:18:10 2004 @@ -35,7 +35,10 @@ 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 -Nru a/drivers/base/power/suspend.c b/drivers/base/power/suspend.c --- a/drivers/base/power/suspend.c Fri May 28 14:18:10 2004 +++ b/drivers/base/power/suspend.c Fri May 28 14:18:10 2004 @@ -39,7 +39,7 @@ { 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;