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    SubjectRe: [PATCH] ACPI: evaluate _PS3 when entering D3 Cold
    Date
    On Monday, April 23, 2012, Aaron Lu wrote:
    > On Mon, Apr 23, 2012 at 01:43:03PM +0200, Rafael J. Wysocki wrote:
    > > On Monday, April 23, 2012, Aaron Lu wrote:
    > > > Hi Rafael and Ming,
    > > >
    > > > Do you have any more comments on this patch?
    > > > If not, can I have your ack? Thanks.
    > > >
    > > > -Aaron
    > > >
    > > > On Sun, Apr 01, 2012 at 02:18:30AM +0800, Aaron Lu wrote:
    > > > > When entering D3 Cold from a higher device state, evaluate _PS3 first
    > > > > and then make the proper power transition.
    > > > > This is used to solve the ZPODD problem on AMD's platform, _PS3 on such
    > > > > platforms will power off the ODD device and thus make the device enter
    > > > > D3 cold state.
    > > > >
    > > > > Signed-off-by: Aaron Lu <aaron.lu@amd.com>
    > > > > Cc: Andiry Xu <andiry.xu@amd.com>
    > > > > Cc: Alex He <alex.he@amd.com>
    > > > > ---
    > > > > drivers/acpi/bus.c | 17 ++++++++++++++---
    > > > > 1 file changed, 14 insertions(+), 3 deletions(-)
    > > > >
    > > > > diff --git a/drivers/acpi/bus.c b/drivers/acpi/bus.c
    > > > > index 3263b68..68e593f 100644
    > > > > --- a/drivers/acpi/bus.c
    > > > > +++ b/drivers/acpi/bus.c
    > > > > @@ -227,6 +227,8 @@ static int __acpi_bus_set_power(struct acpi_device *device, int state)
    > > > > int result = 0;
    > > > > acpi_status status = AE_OK;
    > > > > char object_name[5] = { '_', 'P', 'S', '0' + state, '\0' };
    > > > > + struct acpi_device_power_state *ps;
    > > > > + u8 explicit_set;
    > > > >
    > > > > if (!device || (state < ACPI_STATE_D0) || (state > ACPI_STATE_D3_COLD))
    > > > > return -EINVAL;
    > > > > @@ -239,7 +241,8 @@ static int __acpi_bus_set_power(struct acpi_device *device, int state)
    > > > > return 0;
    > > > > }
    > > > >
    > > > > - if (!device->power.states[state].flags.valid) {
    > > > > + ps = &device->power.states[state];
    > > > > + if (!ps->flags.valid) {
    > > > > printk(KERN_WARNING PREFIX "Device does not support D%d\n", state);
    > > > > return -ENODEV;
    > > > > }
    > > > > @@ -263,7 +266,7 @@ static int __acpi_bus_set_power(struct acpi_device *device, int state)
    > > > > if (result)
    > > > > goto end;
    > > > > }
    > > > > - if (device->power.states[state].flags.explicit_set) {
    > > > > + if (ps->flags.explicit_set) {
    > > > > status = acpi_evaluate_object(device->handle,
    > > > > object_name, NULL, NULL);
    > > > > if (ACPI_FAILURE(status)) {
    > > > > @@ -272,7 +275,15 @@ static int __acpi_bus_set_power(struct acpi_device *device, int state)
    > > > > }
    > > > > }
    > > > > } else {
    > > > > - if (device->power.states[state].flags.explicit_set) {
    > > > > + /* If state is D3 Cold, try to evaluate _PS3 first */
    > > > > + if (state == ACPI_STATE_D3_COLD) {
    > > > > + explicit_set = (ps - 1)->flags.explicit_set;
    > > > > + object_name[3] -= 1;
    > > > > + }
    > > > > + else {
    > > > > + explicit_set = ps->flags.explicit_set;
    > > > > + }
    > >
    > > I really don't like this. I think you should modify acpi_bus_get_power_flags(),
    > > on top of the recent Lin Ming's patch, so that it sets flags.explicit_set for
    > > D3_COLD if _PS3 is present and _PR3 is not.
    > >
    >
    > Thanks for your comments.
    >
    > > I'm not sure you'll need the $subject patch any more then.
    > >
    >
    > A little change is still required. I attached the code below.
    > BTW, I think _PS3 will also need be executed if both _PS3 and _PR3
    > available when putting a device into D3cold.

    Yes, ACPI 5.0 seems to indicate so at least.

    > diff --git a/drivers/acpi/bus.c b/drivers/acpi/bus.c
    > index 3263b68..187433f 100644
    > --- a/drivers/acpi/bus.c
    > +++ b/drivers/acpi/bus.c
    > @@ -273,6 +273,9 @@ static int __acpi_bus_set_power(struct acpi_device *device, int state)
    > }
    > } else {
    > if (device->power.states[state].flags.explicit_set) {
    > + /* evaluate _PS3 instead of _PS4 when entering D3Cold */
    > + if (state == ACPI_STATE_D3)
    > + object_name[3] -= 1;

    Can you just put '3' here directly? That'll be much cleaner than the
    subtraction (that could have been -- as well).

    > status = acpi_evaluate_object(device->handle,
    > object_name, NULL, NULL);
    > if (ACPI_FAILURE(status)) {
    > diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
    > index 7417267..de2ae10 100644
    > --- a/drivers/acpi/scan.c
    > +++ b/drivers/acpi/scan.c
    > @@ -887,8 +887,12 @@ static int acpi_bus_get_power_flags(struct acpi_device *device)
    > /* Evaluate "_PSx" to see if we can do explicit sets */
    > object_name[2] = 'S';
    > status = acpi_get_handle(device->handle, object_name, &handle);
    > - if (ACPI_SUCCESS(status))
    > + if (ACPI_SUCCESS(status)) {
    > ps->flags.explicit_set = 1;
    > + /* Also set D3Cold's explicit flag when _PS3 exists */
    > + if (i == ACPI_STATE_D3_HOT)
    > + (ps+1)->flags.explicit_set = 1;

    Please don't use pointer arithmetics here. I know it _happens_ to work,
    but I don't think it's appropriate in this situation at all.

    > + }
    >
    > /*
    > * State is valid if there are means to put the device into it.

    Thanks,
    Rafael


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