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Message-Id: <201204192239.55048.rjw@sisk.pl>
Date: Thu, 19 Apr 2012 22:39:54 +0200
From: "Rafael J. Wysocki" <rjw@...k.pl>
To: Lin Ming <ming.m.lin@...el.com>
Cc: huang ying <huang.ying.caritas@...il.com>,
Len Brown <lenb@...nel.og>, linux-kernel@...r.kernel.org,
linux-acpi@...r.kernel.org, Zhang Rui <rui.zhang@...el.com>,
Aaron Lu <aaron.lu@....com>
Subject: Re: [PATCH 1/6] ACPI: D3cold state is always valid
On Thursday, April 19, 2012, Lin Ming wrote:
> On Thu, 2012-04-19 at 13:51 +0200, Rafael J. Wysocki wrote:
> > On Thursday, April 19, 2012, huang ying wrote:
> > > On Thu, Apr 19, 2012 at 5:13 AM, Rafael J. Wysocki <rjw@...k.pl> wrote:
> > > > On Tuesday, April 17, 2012, huang ying wrote:
> > > >> On Tue, Apr 17, 2012 at 1:47 PM, Lin Ming <ming.m.lin@...el.com> wrote:
> > > >> > ACPI_STATE_D3 actually means ACPI D3hot which is not always valid.
> > > >> > Instead, ACPI D3cold is always valid.
> > > >> >
> > > >> > Signed-off-by: Lin Ming <ming.m.lin@...el.com>
> > > >> > ---
> > > >> > drivers/acpi/scan.c | 11 ++---------
> > > >> > 1 files changed, 2 insertions(+), 9 deletions(-)
> > > >> >
> > > >> > diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
> > > >> > index 767e2dc..fb56388 100644
> > > >> > --- a/drivers/acpi/scan.c
> > > >> > +++ b/drivers/acpi/scan.c
> > > >> > @@ -884,13 +884,6 @@ static int acpi_bus_get_power_flags(struct acpi_device *device)
> > > >> > acpi_bus_add_power_resource(ps->resources.handles[j]);
> > > >> > }
> > > >> >
> > > >> > - /* The exist of _PR3 indicates D3Cold support */
> > > >> > - if (i == ACPI_STATE_D3) {
> > > >> > - status = acpi_get_handle(device->handle, object_name, &handle);
> > > >> > - if (ACPI_SUCCESS(status))
> > > >> > - device->power.states[ACPI_STATE_D3_COLD].flags.valid = 1;
> > > >> > - }
> > > >> > -
> > > >> > /* Evaluate "_PSx" to see if we can do explicit sets */
> > > >> > object_name[2] = 'S';
> > > >> > status = acpi_get_handle(device->handle, object_name, &handle);
> > > >> > @@ -908,8 +901,8 @@ static int acpi_bus_get_power_flags(struct acpi_device *device)
> > > >> > /* Set defaults for D0 and D3 states (always valid) */
> > > >> > device->power.states[ACPI_STATE_D0].flags.valid = 1;
> > > >> > device->power.states[ACPI_STATE_D0].power = 100;
> > > >> > - device->power.states[ACPI_STATE_D3].flags.valid = 1;
> > > >> > - device->power.states[ACPI_STATE_D3].power = 0;
> > > >> > + device->power.states[ACPI_STATE_D3_COLD].flags.valid = 1;
> > > >> > + device->power.states[ACPI_STATE_D3_COLD].power = 0;
> > > >> >
> > > >> > acpi_bus_init_power(device);
> > > >>
> > > >> I think D3_HOT should be always valid, while D3_COLD should be valid
> > > >> for some situation.
> > > >
> > > > This need not be PCI, mind you.
> > > >
> > > >> - has _PS3, no _PR3
> > > >> - support D3_HOT, D3_COLD
> > > >
> > > > Nope. D3_HOT cannot be supported in that case at the ACPI level.
> > > >
> > > >> - set state
> > > >> - D3_HOT: do nothing in ACPI
> > > >
> > > > That is not D3_HOT, then, from the ACPI point of view. It is a different
> > > > power state.
> > > >
> > > > Suppose you have a non-PCI device that can be only power-manageable via ACPI
> > > > and that device has only _PS0 and _PS3. How would you put it into D3_HOT,
> > > > in particular?
> > >
> > > Normally, we will put it into D3_COLD (via _PS3).
> > >
> > > If it is prevented to be put in D3_COLD,
> > > - If D3_HOT is not marked as supported, we will keep it in D0
> > > - otherwise, we advocate we put it into D3_HOT, but in fact, it is in D0.
> > >
> > > The result is same, but with wrong name.
> > >
> > > But there will be some real problem if we have something like CPU
> > > governor. Because governor may choose D3_HOT for device.
> >
> > In that case the ACPI layer should simply return an error code indicating
> > that the requested state is not available _from_ _it_. If there are
> > more layers, however, they may be able to change the power state of
> > the device.
> >
> > > But for PCI device, D3_HOT is supported for the device.
> >
> > Yes, if the device supports native PM. However, PCI D-states and ACPI D-states
> > are different things. We kind of combine them in our PCI bus type.
> >
> > > So the bus layer should combine the information from native power
> > > state supported and ACPI power state supported to determine which
> > > power states are supported?
> >
> > Yes, we do that all the time, with the exception of D3 cold/hot.
> >
> > > For example, for a PCI device, ACPI advocates D0 and D3_COLD are supported,
> > > and PCI layer may advocate D0, D3_HOT and D3_COLD are supported.
> >
> > Exactly. All of the available power states of the device depend on both
> > the device's own capabilities (ie. what PCI D-states the device may be
> > programmed into by register writes) and whatever is available from ACPI.
> >
> > On embedded systems there are other factors as well.
>
> So seems the patch is much simpler.
Yes, it should be simpler.
> How about below?
It looks good to me. Feel free to add my ACK to the final version.
Thanks,
Rafael
> drivers/acpi/power.c | 2 +-
> drivers/acpi/scan.c | 9 +--------
> drivers/pci/pci-acpi.c | 4 ++--
> include/acpi/actypes.h | 7 ++++---
> 4 files changed, 8 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/acpi/power.c b/drivers/acpi/power.c
> index 7049a7d..330bb4d 100644
> --- a/drivers/acpi/power.c
> +++ b/drivers/acpi/power.c
> @@ -631,7 +631,7 @@ int acpi_power_get_inferred_state(struct acpi_device *device, int *state)
> * We know a device's inferred power state when all the resources
> * required for a given D-state are 'on'.
> */
> - for (i = ACPI_STATE_D0; i < ACPI_STATE_D3; i++) {
> + for (i = ACPI_STATE_D0; i < ACPI_STATE_D3_HOT; i++) {
> list = &device->power.states[i].resources;
> if (list->count < 1)
> continue;
> diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
> index 767e2dc..fbf38ad 100644
> --- a/drivers/acpi/scan.c
> +++ b/drivers/acpi/scan.c
> @@ -869,7 +869,7 @@ static int acpi_bus_get_power_flags(struct acpi_device *device)
> /*
> * Enumerate supported power management states
> */
> - for (i = ACPI_STATE_D0; i <= ACPI_STATE_D3; i++) {
> + for (i = ACPI_STATE_D0; i <= ACPI_STATE_D3_HOT; i++) {
> struct acpi_device_power_state *ps = &device->power.states[i];
> char object_name[5] = { '_', 'P', 'R', '0' + i, '\0' };
>
> @@ -884,13 +884,6 @@ static int acpi_bus_get_power_flags(struct acpi_device *device)
> acpi_bus_add_power_resource(ps->resources.handles[j]);
> }
>
> - /* The exist of _PR3 indicates D3Cold support */
> - if (i == ACPI_STATE_D3) {
> - status = acpi_get_handle(device->handle, object_name, &handle);
> - if (ACPI_SUCCESS(status))
> - device->power.states[ACPI_STATE_D3_COLD].flags.valid = 1;
> - }
> -
> /* Evaluate "_PSx" to see if we can do explicit sets */
> object_name[2] = 'S';
> status = acpi_get_handle(device->handle, object_name, &handle);
> diff --git a/drivers/pci/pci-acpi.c b/drivers/pci/pci-acpi.c
> index 0f150f2..1929c0c 100644
> --- a/drivers/pci/pci-acpi.c
> +++ b/drivers/pci/pci-acpi.c
> @@ -200,7 +200,7 @@ static pci_power_t acpi_pci_choose_state(struct pci_dev *pdev)
> return PCI_D1;
> case ACPI_STATE_D2:
> return PCI_D2;
> - case ACPI_STATE_D3:
> + case ACPI_STATE_D3_HOT:
> return PCI_D3hot;
> case ACPI_STATE_D3_COLD:
> return PCI_D3cold;
> @@ -223,7 +223,7 @@ static int acpi_pci_set_power_state(struct pci_dev *dev, pci_power_t state)
> [PCI_D0] = ACPI_STATE_D0,
> [PCI_D1] = ACPI_STATE_D1,
> [PCI_D2] = ACPI_STATE_D2,
> - [PCI_D3hot] = ACPI_STATE_D3,
> + [PCI_D3hot] = ACPI_STATE_D3_HOT,
> [PCI_D3cold] = ACPI_STATE_D3
> };
> int error = -EINVAL;
> diff --git a/include/acpi/actypes.h b/include/acpi/actypes.h
> index eba6604..e8bcc47 100644
> --- a/include/acpi/actypes.h
> +++ b/include/acpi/actypes.h
> @@ -499,9 +499,10 @@ typedef u64 acpi_integer;
> #define ACPI_STATE_D0 (u8) 0
> #define ACPI_STATE_D1 (u8) 1
> #define ACPI_STATE_D2 (u8) 2
> -#define ACPI_STATE_D3 (u8) 3
> -#define ACPI_STATE_D3_COLD (u8) 4
> -#define ACPI_D_STATES_MAX ACPI_STATE_D3_COLD
> +#define ACPI_STATE_D3_HOT (u8) 3
> +#define ACPI_STATE_D3 (u8) 4
> +#define ACPI_STATE_D3_COLD ACPI_STATE_D3
> +#define ACPI_D_STATES_MAX ACPI_STATE_D3
> #define ACPI_D_STATE_COUNT 5
>
> #define ACPI_STATE_C0 (u8) 0
>
>
>
>
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