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Disable DSM if power resources are in use

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The Optimus _DSM function would prepare a device to be put in D3cold
state when _PS3 is called. Newer laptops should not use this since
Windows 8 introduced a new method to put devices in D3cold state[1].

Hopefully this fixes an infinite loop on a Clevo P651RA. Actually
putting the parent device (PCIe port) is not done in this patch.

 [1]: https://msdn.microsoft.com/windows/hardware/drivers/bringup/firmware-requirements-for-d3cold
This commit is contained in:
Peter Wu 2016-05-13 19:33:07 +02:00
parent 0c38f97c3a
commit 915413ab92
1 changed files with 23 additions and 1 deletions
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24
bbswitch.c
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@ -197,6 +197,26 @@ static int bbswitch_optimus_dsm(void) {
return 0; return 0;
} }
// Windows 8/8.1/10 do not use DSM to put the device in D3cold state,
// instead it disables power resources on the parent PCIe port device.
static bool has_pr3_support(void) {
acpi_handle parent_handle;
struct acpi_device *ad = NULL;
if (ACPI_FAILURE(acpi_get_parent(dis_handle, &parent_handle))) {
pr_warn("Failed to obtain the parent device\n");
return false;
}
acpi_bus_get_device(parent_handle, &ad);
if (!ad) {
pr_warn("Failed to obtain an ACPI device for handle\n");
return false;
}
return ad->power.flags.power_resources;
}
static int bbswitch_acpi_off(void) { static int bbswitch_acpi_off(void) {
if (dsm_type == DSM_TYPE_NVIDIA) { if (dsm_type == DSM_TYPE_NVIDIA) {
char args[] = {2, 0, 0, 0}; char args[] = {2, 0, 0, 0};
@ -436,7 +456,9 @@ static int __init bbswitch_init(void) {
return -ENODEV; return -ENODEV;
} }
if (!skip_optimus_dsm && if (has_pr3_support()) {
pr_info("skipping _DSM as _PR3 support is detected\n");
} else if (!skip_optimus_dsm &&
has_dsm_func(acpi_optimus_dsm_muid, 0x100, 0x1A)) { has_dsm_func(acpi_optimus_dsm_muid, 0x100, 0x1A)) {
dsm_type = DSM_TYPE_OPTIMUS; dsm_type = DSM_TYPE_OPTIMUS;
pr_info("detected an Optimus _DSM function\n"); pr_info("detected an Optimus _DSM function\n");