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SubjectRe: [PATCH v2] firewire: ohci: Convert to generic power management
On Tue, Jun 07, 2022 at 04:21:57PM -0500, Bjorn Helgaas wrote:
> From: Vaibhav Gupta <vaibhavgupta40@gmail.com>
>
> Convert firewire-ohci from legacy PCI power management to the generic power
> management framework.
>
> Previously firewire-ohci used legacy PCI power management, and
> pci_suspend() and pci_resume() were responsible for both device-specific
> things and generic PCI things like saving and restoring config space and
> managing power state:
>
> pci_suspend
> software_reset <-- device-specific
> pci_save_state <-- generic PCI
> pci_set_power_state <-- generic PCI
> pmac_ohci_off <-- device-specific
>
> pci_resume
> pmac_ohci_on <-- device-specific
> pci_set_power_state(PCI_D0) <-- generic PCI
> pci_restore_state <-- generic PCI
> pci_enable_device <-- generic PCI
> ohci_enable <-- device-specific
>
> Convert to generic power management where the PCI bus PM methods do the
> generic PCI things, and the driver needs only the device-specific part,
> i.e.,
>
> suspend_devices_and_enter
> dpm_suspend_start(PMSG_SUSPEND)
> pci_pm_suspend # PCI bus .suspend() method
> pci_suspend # driver->pm->suspend
> software_reset <-- device-specific
> pmac_ohci_off <-- device-specific
> suspend_enter
> dpm_suspend_noirq(PMSG_SUSPEND)
> pci_pm_suspend_noirq # PCI bus .suspend_noirq() method
> pci_save_state <-- generic PCI
> pci_prepare_to_sleep <-- generic PCI
> pci_set_power_state
> ...
> dpm_resume_end(PMSG_RESUME)
> pci_pm_resume # PCI bus .resume() method
> pci_restore_standard_config
> pci_set_power_state(PCI_D0) <-- generic PCI
> pci_restore_state <-- generic PCI
> pci_resume # driver->pm->resume
> pmac_ohci_on <-- device-specific
> ohci_enable <-- device-specific

I want to point out that this changes the ordering of pmac_ohci_off()
with respect to pci_save_state() and pci_set_power_state().
Previously we did those as:

pci_save_state
pci_set_power_state
pmac_ohci_off

and after this patch it would be:

pmac_ohci_off
pci_save_state
pci_set_power_state

The ordering of pmac_ohci_on() in the resume path is similarly
changed.

I don't know what pmac_ohci_off() and pmac_ohci_on() do, so I don't
know whether this is an issue. In general, drivers don't need to do
anything after their device is put in D3hot, but maybe firewire-ohci
is unique in this way.

> [bhelgaas: commit log]
> Link: https://lore.kernel.org/r/20200720150715.624520-1-vaibhavgupta40@gmail.com
> Signed-off-by: Vaibhav Gupta <vaibhavgupta40@gmail.com>
> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
> ---
> drivers/firewire/ohci.c | 35 ++++++++---------------------------
> 1 file changed, 8 insertions(+), 27 deletions(-)
>
> diff --git a/drivers/firewire/ohci.c b/drivers/firewire/ohci.c
> index 17c9d825188b..aee705132330 100644
> --- a/drivers/firewire/ohci.c
> +++ b/drivers/firewire/ohci.c
> @@ -3165,8 +3165,7 @@ static int ohci_set_iso_channels(struct fw_iso_context *base, u64 *channels)
> return ret;
> }
>
> -#ifdef CONFIG_PM
> -static void ohci_resume_iso_dma(struct fw_ohci *ohci)
> +static void __maybe_unused ohci_resume_iso_dma(struct fw_ohci *ohci)
> {
> int i;
> struct iso_context *ctx;
> @@ -3183,7 +3182,6 @@ static void ohci_resume_iso_dma(struct fw_ohci *ohci)
> ohci_start_iso(&ctx->base, 0, ctx->sync, ctx->tags);
> }
> }
> -#endif
>
> static int queue_iso_transmit(struct iso_context *ctx,
> struct fw_iso_packet *packet,
> @@ -3789,39 +3787,24 @@ static void pci_remove(struct pci_dev *dev)
> dev_notice(&dev->dev, "removed fw-ohci device\n");
> }
>
> -#ifdef CONFIG_PM
> -static int pci_suspend(struct pci_dev *dev, pm_message_t state)
> +static int __maybe_unused pci_suspend(struct device *devp)
> {
> + struct pci_dev *dev = to_pci_dev(devp);
> struct fw_ohci *ohci = pci_get_drvdata(dev);
> - int err;
>
> software_reset(ohci);
> - err = pci_save_state(dev);
> - if (err) {
> - ohci_err(ohci, "pci_save_state failed\n");
> - return err;
> - }
> - err = pci_set_power_state(dev, pci_choose_state(dev, state));
> - if (err)
> - ohci_err(ohci, "pci_set_power_state failed with %d\n", err);
> pmac_ohci_off(dev);
>
> return 0;
> }
>
> -static int pci_resume(struct pci_dev *dev)
> +static int __maybe_unused pci_resume(struct device *devp)
> {
> + struct pci_dev *dev = to_pci_dev(devp);
> struct fw_ohci *ohci = pci_get_drvdata(dev);
> int err;
>
> pmac_ohci_on(dev);
> - pci_set_power_state(dev, PCI_D0);
> - pci_restore_state(dev);
> - err = pci_enable_device(dev);
> - if (err) {
> - ohci_err(ohci, "pci_enable_device failed\n");
> - return err;
> - }
>
> /* Some systems don't setup GUID register on resume from ram */
> if (!reg_read(ohci, OHCI1394_GUIDLo) &&
> @@ -3838,7 +3821,6 @@ static int pci_resume(struct pci_dev *dev)
>
> return 0;
> }
> -#endif
>
> static const struct pci_device_id pci_table[] = {
> { PCI_DEVICE_CLASS(PCI_CLASS_SERIAL_FIREWIRE_OHCI, ~0) },
> @@ -3847,15 +3829,14 @@ static const struct pci_device_id pci_table[] = {
>
> MODULE_DEVICE_TABLE(pci, pci_table);
>
> +static SIMPLE_DEV_PM_OPS(pci_pm_ops, pci_suspend, pci_resume);
> +
> static struct pci_driver fw_ohci_pci_driver = {
> .name = ohci_driver_name,
> .id_table = pci_table,
> .probe = pci_probe,
> .remove = pci_remove,
> -#ifdef CONFIG_PM
> - .resume = pci_resume,
> - .suspend = pci_suspend,
> -#endif
> + .driver.pm = &pci_pm_ops,
> };
>
> static int __init fw_ohci_init(void)
> --
> 2.25.1
>

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