On Fri, 2023-06-09 at 09:46 +0200, AngeloGioacchino Del Regno wrote:
>
> Il 09/06/23 04:30, Zhiren Chen ha scritto:
> > From: Zhiren Chen <Zhiren.Chen@xxxxxxxxxxxx>
> >
> > The platform_pci_choose_state function and other low-level platform
> > interfaces used by PCI power management processing did not take
>
> into
> > account non-ACPI-supported platforms. This shortcoming can result
>
> in
> > limitations and issues.
> >
> > For example, in embedded systems like smartphones, a PCI device can
>
> be
> > shared by multiple processors for different purposes. The PCI
>
> device and
> > some of the processors are controlled by Linux, while the rest of
>
> the
> > processors runs its own operating system.
> > When Linux initiates system-level sleep, if it does not consider
>
> the
> > working state of the shared PCI device and forcefully sets the PCI
>
> device
> > state to D3, it will affect the functionality of other processors
>
> that
> > are currently using the PCI device.
> >
> > To address this problem, an interface should be created for PCI
>
> devices
> > that don't support ACPI to enable accurate reporting of the power
>
> state
> > during the PCI PM handling process.
> >
> > Signed-off-by: Zhiren Chen <Zhiren.Chen@xxxxxxxxxxxx>
> > ---
> > drivers/pci/pci.c | 24 ++++++++++++++++++++++++
> > drivers/pci/pci.h | 40 ++++++++++++++++++++++++++++++++++++++++
> > include/linux/pci.h | 1 +
> > 3 files changed, 65 insertions(+)
> >
> > diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> > index 5ede93222bc1..9f03406f3081 100644
> > --- a/drivers/pci/pci.c
> > +++ b/drivers/pci/pci.c
> > @@ -1014,6 +1014,9 @@ static void pci_restore_bars(struct pci_dev
>
> *dev)
> >
> > static inline bool platform_pci_power_manageable(struct pci_dev
>
> *dev)
> > {
> > +if (dev->platform_pm_ops && dev->platform_pm_ops->is_manageable)
> > +return dev->platform_pm_ops->is_manageable(dev);
> > +
> > if (pci_use_mid_pm())
> > return true;
> >
> > @@ -1023,6 +1026,9 @@ static inline bool
>
> platform_pci_power_manageable(struct pci_dev *dev)
> > static inline int platform_pci_set_power_state(struct pci_dev
>
> *dev,
> > pci_power_t t)
> > {
> > +if (dev->platform_pm_ops && dev->platform_pm_ops->set_state)
> > +return dev->platform_pm_ops->set_state(dev, t);
> > +
> > if (pci_use_mid_pm())
> > return mid_pci_set_power_state(dev, t);
> >
> > @@ -1031,6 +1037,9 @@ static inline int
>
> platform_pci_set_power_state(struct pci_dev *dev,
> >
> > static inline pci_power_t platform_pci_get_power_state(struct
>
> pci_dev *dev)
> > {
> > +if (dev->platform_pm_ops && dev->platform_pm_ops->get_state)
> > +return dev->platform_pm_ops->get_state(dev);
> > +
> > if (pci_use_mid_pm())
> > return mid_pci_get_power_state(dev);
> >
> > @@ -1039,12 +1048,18 @@ static inline pci_power_t
>
> platform_pci_get_power_state(struct pci_dev *dev)
> >
> > static inline void platform_pci_refresh_power_state(struct
>
> pci_dev *dev)
> > {
> > +if (dev->platform_pm_ops && dev->platform_pm_ops->refresh_state)
> > +dev->platform_pm_ops->refresh_state(dev);
> > +
> > if (!pci_use_mid_pm())
> > acpi_pci_refresh_power_state(dev);
> > }
> >
> > static inline pci_power_t platform_pci_choose_state(struct
>
> pci_dev *dev)
> > {
> > +if (dev->platform_pm_ops && dev->platform_pm_ops->choose_state)
> > +return dev->platform_pm_ops->choose_state(dev);
> > +
> > if (pci_use_mid_pm())
> > return PCI_POWER_ERROR;
> >
> > @@ -1053,6 +1068,9 @@ static inline pci_power_t
>
> platform_pci_choose_state(struct pci_dev *dev)
> >
> > static inline int platform_pci_set_wakeup(struct pci_dev *dev,
>
> bool enable)
> > {
> > +if (dev->platform_pm_ops && dev->platform_pm_ops->set_wakeup)
> > +return dev->platform_pm_ops->set_wakeup(dev, enable);
> > +
> > if (pci_use_mid_pm())
> > return PCI_POWER_ERROR;
> >
> > @@ -1061,6 +1079,9 @@ static inline int
>
> platform_pci_set_wakeup(struct pci_dev *dev, bool enable)
> >
> > static inline bool platform_pci_need_resume(struct pci_dev *dev)
> > {
> > +if (dev->platform_pm_ops && dev->platform_pm_ops->need_resume)
> > +return dev->platform_pm_ops->need_resume(dev);
> > +
> > if (pci_use_mid_pm())
> > return false;
> >
> > @@ -1069,6 +1090,9 @@ static inline bool
>
> platform_pci_need_resume(struct pci_dev *dev)
> >
> > static inline bool platform_pci_bridge_d3(struct pci_dev *dev)
> > {
> > +if (dev->platform_pm_ops && dev->platform_pm_ops->bridge_d3)
> > +return dev->platform_pm_ops->bridge_d3(dev);
> > +
> > if (pci_use_mid_pm())
> > return false;
> >
> > diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
> > index 2475098f6518..85154470c083 100644
> > --- a/drivers/pci/pci.h
> > +++ b/drivers/pci/pci.h
> > @@ -71,6 +71,42 @@ struct pci_cap_saved_state
>
> *pci_find_saved_ext_cap(struct pci_dev *dev,
> > */
> > #define PCI_RESET_WAIT1000/* msec */
> >
> > +/**
> > + * struct pci_platform_pm_ops - Firmware PM callbacks
> > + *
> > + * @is_manageable: returns 'true' if given device is power
>
> manageable by the
> > + * platform firmware
> > + *
> > + * @set_state: invokes the platform firmware to set the device's
>
> power state
> > + *
> > + * @get_state: queries the platform firmware for a device's
>
> current power state
> > + *
> > + * @choose_state: returns PCI power state of given device
>
> preferred by the
> > + * platform; to be used during system-wide
>
> transitions from a
> > + * sleeping state to the working state and vice
>
> versa
> > + *
> > + * @set_wakeup: enables/disables wakeup capability for the device
> > + *
> > + * @need_resume: returns 'true' if the given device (which is
>
> currently
> > + *suspended) needs to be resumed to be configured for system
> > + *wakeup.
> > + *
> > + * @bridge_d3: return 'true' if given device supoorts D3 when it
>
> is a bridge
> > + *
> > + * @refresh_state: refresh the given device's power state
> > + *
> > + */
> > +struct pci_platform_pm_ops {
> > +bool (*is_manageable)(struct pci_dev *dev);
> > +int (*set_state)(struct pci_dev *dev, pci_power_t state);
> > +pci_power_t (*get_state)(struct pci_dev *dev);
> > +pci_power_t (*choose_state)(struct pci_dev *dev);
> > +int (*set_wakeup)(struct pci_dev *dev, bool enable);
> > +bool (*need_resume)(struct pci_dev *dev);
> > +bool (*bridge_d3)(struct pci_dev *dev);
> > +void (*refresh_state)(struct pci_dev *dev);
> > +};
> > +
> > void pci_update_current_state(struct pci_dev *dev, pci_power_t
>
> state);
> > void pci_refresh_power_state(struct pci_dev *dev);
> > int pci_power_up(struct pci_dev *dev);
> > @@ -96,6 +132,10 @@ void pci_bridge_d3_update(struct pci_dev *dev);
> > void pci_bridge_reconfigure_ltr(struct pci_dev *dev);
> > int pci_bridge_wait_for_secondary_bus(struct pci_dev *dev, char
>
> *reset_type);
> >
> > +static inline void pci_set_platform_pm(struct pci_dev *dev, struct
>
> pci_platform_pm_ops *ops)
>
> pci_set_platform_pm_ops()
>
> Anyway ... can you please also show an user of this mechanism? I
> would imagine that
> the user would be pcie-mediatek-gen3?
>
All PCI devices include pcie-mediatek-gen3 can be user of this
mechanism
> Please send a patch that implements usage of those platform_pm_ops in
> the same
> series as this one.
>
> Thanks,
> Angelo
>
I cann't provide the patch based on the already existing PCI driver
in kernel because implemention of platform_pm_ops depends on user's
PM policy that I don't konw.
The user needing platform_pm_ops I know is Mediatek T8xx modem chip
whose driver is currently under review.
(ref:
https://patchwork.kernel.org/project/netdevbpf/cover/20230317080942.183514-1-yanchao.yang@xxxxxxxxxxxx/
)
I'd like to use the T8xx driver as an example to illustrate how this
mechanism is used:
In system-wild suspend flow, T8xx may require to stay alive because it
is used by other hardware component that is not under conrol of kernel.
In this case, T8xx driver can implement choose_state() to check a
status register to obtain the working state of the T8xx. if T8xx is
busy, choose_state() return D0 to skip D3 setting in
pci_pm_suspend_noirq.
Best Regards,
Zhiren
> > +{
> > +dev->platform_pm_ops = ops;
> > +}
> > static inline void pci_wakeup_event(struct pci_dev *dev)
> > {
> > /* Wait 100 ms before the system can be put into a sleep state.
>
> */
> > diff --git a/include/linux/pci.h b/include/linux/pci.h
> > index 60b8772b5bd4..a0171f1abf2f 100644
> > --- a/include/linux/pci.h
> > +++ b/include/linux/pci.h
> > @@ -327,6 +327,7 @@ struct pci_dev {
> > void*sysdata;/* Hook for sys-specific extension */
> > struct proc_dir_entry *procent;/* Device entry in /proc/bus/pci
>
> */
> > struct pci_slot*slot;/* Physical slot this device is in */
> > +struct pci_platform_pm_ops *platform_pm_ops;
> >
> > unsigned intdevfn;/* Encoded device & function index */
> > unsigned shortvendor;
