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Message-ID: <CAErSpo5gid5QuKCevURft_Cm+5zF2RC=iDxrFXWiCF+1r=4oAg@mail.gmail.com>
Date: Fri, 4 May 2012 13:51:16 -0600
From: Bjorn Helgaas <bhelgaas@...gle.com>
To: Huang Ying <ying.huang@...el.com>
Cc: ming.m.lin@...el.com, linux-kernel@...r.kernel.org,
linux-pm@...r.kernel.org, "Rafael J. Wysocki" <rjw@...k.pl>,
Zheng Yan <zheng.z.yan@...el.com>
Subject: Re: [RFC v2 5/5] PCIe, Add PCIe runtime D3cold support
On Fri, May 4, 2012 at 2:13 AM, Huang Ying <ying.huang@...el.com> wrote:
> This patch adds runtime D3cold support to PCIe bus. D3cold is the
> deepest power saving state for PCIe devices. Where the main PCIe link
> will be powered off totally, so before the PCIe main link is powered
> on again, you can not access the device, even the configuration space,
> which is still accessible in D3hot. Because the main PCIe link is not
> available, the PCI PM registers can not be used to put device into/out
> of D3cold state, that will be done by platform logic such as ACPI
> _PR3.
>
> To support remote wake up in D3cold, aux power is supplied, and a
> side-band pin: WAKE# is used to notify remote wake up event, the pin
> is usually connected to platform logic such as ACPI GPE. This is
> quite different with other power saving states, where remote wake up
> is notified via PME message via the PCIe main link.
>
> PCIe devices in plug-in slot usually has no direct platform logic, for
> example, there is usually no ACPI _PR3 for them. The D3cold support
> for these devices can be done via the PCIe port connected to it. When
> power on/off the PCIe port, the corresponding PCIe devices are powered
> on/off too. And the remote wake up event from PCIe device will be
> notified to the corresponding PCIe port.
>
> The PCI subsystem D3cold support and corresponding ACPI platform
> support is implemented in the patch. Including the support for PCIe
> devices in plug-in slot.
>
> For more information about PCIe D3cold and corresponding ACPI support,
> please refer to:
>
> - PCI Express Base Specification Revision 2.0
> - Advanced Configuration and Power Interface Specification Revision 5.0
>
> Originally-by: Zheng Yan <zheng.z.yan@...el.com>
> Signed-off-by: Huang Ying <ying.huang@...el.com>
> ---
> drivers/pci/pci-acpi.c | 32 +++++++++--
> drivers/pci/pci-driver.c | 3 +
> drivers/pci/pci.c | 115 +++++++++++++++++++++++++++++++++++++----
> drivers/pci/pci.h | 1
> drivers/pci/pcie/portdrv_pci.c | 28 +++++++++
> include/linux/pci.h | 12 +++-
> 6 files changed, 175 insertions(+), 16 deletions(-)
>
> --- a/drivers/pci/pci-acpi.c
> +++ b/drivers/pci/pci-acpi.c
> @@ -48,6 +48,21 @@ static void pci_acpi_wake_dev(acpi_handl
> if (event != ACPI_NOTIFY_DEVICE_WAKE || !pci_dev)
> return;
>
> + if (pci_dev->current_state == PCI_D3cold) {
> + unsigned int count = 0;
> +
> + /*
> + * Powering on bridge need to resume whole hierarchy,
> + * just resume the children to avoid the bridge going
> + * suspending as soon as resumed
> + */ at
> + if (pci_dev->subordinate)
> + count = pci_wakeup_bus(pci_dev->subordinate);
> + if (count == 0)
> + pm_runtime_resume(&pci_dev->dev);
> + return;
> + }
> +
> if (!pci_dev->pm_cap || !pci_dev->pme_support
> || pci_check_pme_status(pci_dev)) {
> if (pci_dev->pme_poll)
> @@ -187,10 +202,13 @@ acpi_status pci_acpi_remove_pm_notifier(
>
> static pci_power_t acpi_pci_choose_state(struct pci_dev *pdev)
> {
> - int acpi_state;
> + int acpi_state, d_max;
>
> - acpi_state = acpi_pm_device_sleep_state(&pdev->dev, NULL,
> - ACPI_STATE_D3);
> + if (pdev->dev.power.power_must_be_on)
> + d_max = ACPI_STATE_D3_HOT;
> + else
> + d_max = ACPI_STATE_D3_COLD;
> + acpi_state = acpi_pm_device_sleep_state(&pdev->dev, NULL, d_max);
> if (acpi_state < 0)
> return PCI_POWER_ERROR;
>
> @@ -297,7 +315,13 @@ static void acpi_pci_propagate_run_wake(
>
> static int acpi_pci_run_wake(struct pci_dev *dev, bool enable)
> {
> - if (dev->pme_interrupt)
> + /*
> + * Per PCI Express Base Specification Revision 2.0 section
> + * 5.3.3.2 Link Wakeup, platform support is needed for D3cold
> + * waking up to power on the main link even if there is PME
> + * support for D3cold
> + */
> + if (dev->pme_interrupt && !dev->runtime_d3cold)
> return 0;
>
> if (!acpi_pm_device_run_wake(&dev->dev, enable))
> --- a/drivers/pci/pci-driver.c
> +++ b/drivers/pci/pci-driver.c
> @@ -1013,10 +1013,13 @@ static int pci_pm_runtime_suspend(struct
> if (!pm || !pm->runtime_suspend)
> return -ENOSYS;
>
> + dev->power.power_must_be_on = false;
> error = pm->runtime_suspend(dev);
> suspend_report_result(pm->runtime_suspend, error);
> if (error)
> return error;
> + if (!dev->power.power_off_user)
> + dev->power.power_must_be_on = true;
>
> pci_fixup_device(pci_fixup_suspend, pci_dev);
>
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -653,6 +653,12 @@ void pci_update_current_state(struct pci
> if (dev->pm_cap) {
> u16 pmcsr;
>
> + /*
> + * Configuration space is not accessible for device in
> + * D3cold, so keep in D3cold for safety
> + */
> + if (dev->current_state == PCI_D3cold)
> + return;
> pci_read_config_word(dev, dev->pm_cap + PCI_PM_CTRL, &pmcsr);
> dev->current_state = (pmcsr & PCI_PM_CTRL_STATE_MASK);
> } else {
> @@ -671,8 +677,11 @@ static int pci_platform_power_transition
>
> if (platform_pci_power_manageable(dev)) {
> error = platform_pci_set_power_state(dev, state);
> - if (!error)
> + if (!error) {
> + if (state == PCI_D3cold)
> + dev->current_state = PCI_D3cold;
> pci_update_current_state(dev, state);
> + }
> /* Fall back to PCI_D0 if native PM is not supported */
> if (!dev->pm_cap)
> dev->current_state = PCI_D0;
> @@ -693,8 +702,49 @@ static int pci_platform_power_transition
> */
> static void __pci_start_power_transition(struct pci_dev *dev, pci_power_t state)
> {
> - if (state == PCI_D0)
> + if (state == PCI_D0) {
> pci_platform_power_transition(dev, PCI_D0);
> + /*
> + * Mandatory power management transition delays, see
> + * PCI Express Base Specification Revision 2.0 Section
> + * 6.6.1: Conventional Reset. Do not delay for
> + * devices powered on/off by corresponding bridge,
> + * because have already delayed for the bridge.
> + */
> + if (dev->runtime_d3cold) {
> + msleep(dev->d3cold_delay);
> + /* When powering on a bridge from D3cold, the
> + * whole hierarchy may be powered on into
> + * D0uninitialized state, resume them to give
> + * them a chance to suspend again */
> + if (dev->subordinate)
> + pci_wakeup_bus(dev->subordinate);
> + }
> + }
> +}
> +
> +/**
> + * __pci_dev_set_current_state - Set current state of a PCI device
> + * @dev: Device to handle
> + * @data: pointer to state to be set
> + */
> +static int __pci_dev_set_current_state(struct pci_dev *dev, void *data)
> +{
> + pci_power_t state = *(pci_power_t *)data;
> +
> + dev->current_state = state;
> + return 0;
> +}
> +
> +/**
> + * __pci_bus_set_current_state - Walk given bus and set current state of devices
> + * @bus: Top bus of the subtree to walk.
> + * @state: state to be set
> + */
> +static void __pci_bus_set_current_state(struct pci_bus *bus, pci_power_t state)
> +{
> + if (bus)
> + pci_walk_bus(bus, __pci_dev_set_current_state, &state);
> }
>
> /**
> @@ -706,8 +756,17 @@ static void __pci_start_power_transition
> */
> int __pci_complete_power_transition(struct pci_dev *dev, pci_power_t state)
> {
> - return state >= PCI_D0 ?
> - pci_platform_power_transition(dev, state) : -EINVAL;
> + int ret;
> +
> + if (state < PCI_D0)
> + return -EINVAL;
> + ret = pci_platform_power_transition(dev, state);
> + if (!ret && state == PCI_D3cold) {
> + /* Power off the bridge may power off the whole hierarchy */
> + if (dev->subordinate)
> + __pci_bus_set_current_state(dev->subordinate, state);
> + }
> + return ret;
> }
> EXPORT_SYMBOL_GPL(__pci_complete_power_transition);
>
> @@ -731,8 +790,8 @@ int pci_set_power_state(struct pci_dev *
> int error;
>
> /* bound the state we're entering */
> - if (state > PCI_D3hot)
> - state = PCI_D3hot;
> + if (state > PCI_D3cold)
> + state = PCI_D3cold;
> else if (state < PCI_D0)
> state = PCI_D0;
> else if ((state == PCI_D1 || state == PCI_D2) && pci_no_d1d2(dev))
> @@ -747,10 +806,15 @@ int pci_set_power_state(struct pci_dev *
>
> /* This device is quirked not to be put into D3, so
> don't put it in D3 */
> - if (state == PCI_D3hot && (dev->dev_flags & PCI_DEV_FLAGS_NO_D3))
> + if (state >= PCI_D3hot && (dev->dev_flags & PCI_DEV_FLAGS_NO_D3))
> return 0;
>
> - error = pci_raw_set_power_state(dev, state);
> + /*
> + * To put device in D3cold, we put device into D3hot in native
> + * way, then put device into D3cold with platform ops
> + */
> + error = pci_raw_set_power_state(dev, state > PCI_D3hot ?
> + PCI_D3hot : state);
>
> if (!__pci_complete_power_transition(dev, state))
> error = 0;
> @@ -1506,6 +1570,34 @@ void pci_pme_wakeup_bus(struct pci_bus *
> }
>
> /**
> + * pci_wakeup - Wake up a PCI device
> + * @dev: Device to handle.
> + * @data: to count how many device are waken up.
> + */
> +static int pci_wakeup(struct pci_dev *dev, void *data)
> +{
> + unsigned int *count = data;
> +
> + pci_wakeup_event(dev);
> + pm_request_resume(&dev->dev);
> + (*count)++;
> + return 0;
> +}
> +
> +/**
> + * pci_wakeup_bus - Walk given bus and wake up devices on it
> + * @bus: Top bus of the subtree to walk.
> + */
> +unsigned int pci_wakeup_bus(struct pci_bus *bus)
> +{
> + unsigned int count = 0;
> +
> + if (bus)
> + pci_walk_bus(bus, pci_wakeup, &count);
> + return count;
> +}
> +
> +/**
> * pci_pme_capable - check the capability of PCI device to generate PME#
> * @dev: PCI device to handle.
> * @state: PCI state from which device will issue PME#.
> @@ -1789,12 +1881,16 @@ int pci_finish_runtime_suspend(struct pc
> if (target_state == PCI_POWER_ERROR)
> return -EIO;
>
> + dev->runtime_d3cold = target_state == PCI_D3cold ? true : false;
> +
> __pci_enable_wake(dev, target_state, true, pci_dev_run_wake(dev));
>
> error = pci_set_power_state(dev, target_state);
>
> - if (error)
> + if (error) {
> __pci_enable_wake(dev, target_state, true, false);
> + dev->runtime_d3cold = false;
> + }
>
> return error;
> }
> @@ -1864,6 +1960,7 @@ void pci_pm_init(struct pci_dev *dev)
>
> dev->pm_cap = pm;
> dev->d3_delay = PCI_PM_D3_WAIT;
> + dev->d3cold_delay = PCI_PM_D3COLD_WAIT;
>
> dev->d1_support = false;
> dev->d2_support = false;
> --- a/drivers/pci/pci.h
> +++ b/drivers/pci/pci.h
> @@ -70,6 +70,7 @@ extern void pci_update_current_state(str
> extern void pci_disable_enabled_device(struct pci_dev *dev);
> extern int pci_finish_runtime_suspend(struct pci_dev *dev);
> extern int __pci_pme_wakeup(struct pci_dev *dev, void *ign);
> +extern unsigned int pci_wakeup_bus(struct pci_bus *bus);
> extern void pci_pm_init(struct pci_dev *dev);
> extern void platform_pci_wakeup_init(struct pci_dev *dev);
> extern void pci_allocate_cap_save_buffers(struct pci_dev *dev);
> --- a/drivers/pci/pcie/portdrv_pci.c
> +++ b/drivers/pci/pcie/portdrv_pci.c
> @@ -101,10 +101,38 @@ static int pcie_port_resume_noirq(struct
> }
>
> #ifdef CONFIG_PM_RUNTIME
> +struct d3cold_info {
> + bool power_must_be_on;
> + unsigned int d3cold_delay;
> +};
> +
> +static int pci_dev_d3cold_info(struct pci_dev *pdev, void *data)
> +{
> + struct d3cold_info *info = data;
> +
> + info->d3cold_delay = max_t(unsigned int, pdev->d3cold_delay,
> + info->d3cold_delay);
> + info->power_must_be_on = info->power_must_be_on ||
> + pdev->dev.power.power_must_be_on;
We don't care what the previous state of info->power_must_be_on was,
so to me, this would read more naturally as:
if (pdev->dev.power.power_must_be_on)
info->power_must_be_on = true;
> + return 0;
> +}
> +
> static int pcie_port_runtime_suspend(struct device *dev)
> {
> struct pci_dev *pdev = to_pci_dev(dev);
> + struct d3cold_info d3cold_info = {
> + .power_must_be_on = dev->power.power_must_be_on,
> + .d3cold_delay = PCI_PM_D3_WAIT,
> + };
>
> + /*
> + * If any subordinate device need to keep power on, we should
> + * not power off the port. The D3cold delay of port should be
> + * the max of that of all subordinate devices.
> + */
> + pci_walk_bus(pdev->subordinate, pci_dev_d3cold_info, &d3cold_info);
> + dev->power.power_must_be_on = d3cold_info.power_must_be_on;
> + pdev->d3cold_delay = d3cold_info.d3cold_delay;
Maybe you've thought about how this works in the presence of hot-added
devices below pdev, but it's not obvious to me that it's safe to cache
power_must_be_on and d3cold_delay in the struct device and struct
pci_dev. Are they guaranteed to be updated when a new device is
hot-added?
> pci_save_state(pdev);
> return 0;
> }
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -132,9 +132,10 @@ static inline const char *pci_power_name
> return pci_power_names[1 + (int) state];
> }
>
> -#define PCI_PM_D2_DELAY 200
> -#define PCI_PM_D3_WAIT 10
> -#define PCI_PM_BUS_WAIT 50
> +#define PCI_PM_D2_DELAY 200
> +#define PCI_PM_D3_WAIT 10
> +#define PCI_PM_D3COLD_WAIT 100
> +#define PCI_PM_BUS_WAIT 50
>
> /** The pci_channel state describes connectivity between the CPU and
> * the pci device. If some PCI bus between here and the pci device
> @@ -282,7 +283,12 @@ struct pci_dev {
> unsigned int mmio_always_on:1; /* disallow turning off io/mem
> decoding during bar sizing */
> unsigned int wakeup_prepared:1;
> + unsigned int runtime_d3cold:1; /* whether go through runtime
> + D3cold, not set for devices
> + powered on/off by the
> + corresponding bridge */
> unsigned int d3_delay; /* D3->D0 transition time in ms */
> + unsigned int d3cold_delay; /* D3cold->D0 transition time in ms */
>
> #ifdef CONFIG_PCIEASPM
> struct pcie_link_state *link_state; /* ASPM link state. */
--
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