Re: [PATCH v1] i2c: eg20t: use generic power management

Bjorn Helgaas
2020-08-05T20:06:42Z

[update Linus's address, drop Qi's (bounced)]

On Wed, Aug 05, 2020 at 10:23:31AM -0500, Bjorn Helgaas wrote:
> [+cc Tomoya, Linus, Qi, Ben from e9bc8fa5df1c]
>
> On Mon, Jul 20, 2020 at 07:30:32PM +0530, Vaibhav Gupta wrote:
> > Drivers using legacy PM have to manage PCI states and device's PM states
> > themselves. They also need to take care of configuration registers.
> >
> > With improved and powerful support of generic PM, PCI Core takes care of
> > above mentioned, device-independent, jobs.
> >
> > This driver makes use of PCI helper functions like
> > pci_save/restore_state(), pci_enable/disable_device(),
> > pci_enable_wake() and pci_set_power_state() to do required operations. In
> > generic mode, they are no longer needed.
> >
> > Change function parameter in both .suspend() and .resume() to
> > "struct device*" type. Use to_pci_dev() and dev_get_drvdata() to get
> > "struct pci_dev*" variable and drv data.
> >
> > Compile-tested only.
> >
> > Signed-off-by: Vaibhav Gupta <vaibhavgupta40@gmail.com>
> > ---
> > drivers/i2c/busses/i2c-eg20t.c | 39 ++++++++--------------------------
> > 1 file changed, 9 insertions(+), 30 deletions(-)
> >
> > diff --git a/drivers/i2c/busses/i2c-eg20t.c b/drivers/i2c/busses/i2c-eg20t.c
> > index 73f139690e4e..c0ddc4cc2ce7 100644
> > --- a/drivers/i2c/busses/i2c-eg20t.c
> > +++ b/drivers/i2c/busses/i2c-eg20t.c
> > @@ -846,11 +846,10 @@ static void pch_i2c_remove(struct pci_dev *pdev)
> > kfree(adap_info);
> > }
> >
> > -#ifdef CONFIG_PM
> > -static int pch_i2c_suspend(struct pci_dev *pdev, pm_message_t state)
> > +static int __maybe_unused pch_i2c_suspend(struct device *dev)
> > {
> > - int ret;
> > int i;
> > + struct pci_dev *pdev = to_pci_dev(dev);
> > struct adapter_info *adap_info = pci_get_drvdata(pdev);
>
> Why don't you use "adap_info = dev_get_drvdata(dev)" as you did below,
> so you don't need to_pci_dev()?
>
> > void __iomem *p = adap_info->pch_data[0].pch_base_address;
> >
> > @@ -872,34 +871,17 @@ static int pch_i2c_suspend(struct pci_dev *pdev, pm_message_t state)
> > ioread32(p + PCH_I2CSR), ioread32(p + PCH_I2CBUFSTA),
> > ioread32(p + PCH_I2CESRSTA));
> >
> > - ret = pci_save_state(pdev);
> > -
> > - if (ret) {
> > - pch_pci_err(pdev, "pci_save_state\n");
> > - return ret;
> > - }
> > -
> > - pci_enable_wake(pdev, PCI_D3hot, 0);
> > - pci_disable_device(pdev);
> > - pci_set_power_state(pdev, pci_choose_state(pdev, state));
> > + device_wakeup_disable(dev);
> >
> > return 0;
> > }
> >
> > -static int pch_i2c_resume(struct pci_dev *pdev)
> > +static int __maybe_unused pch_i2c_resume(struct device *dev)
> > {
> > int i;
> > - struct adapter_info *adap_info = pci_get_drvdata(pdev);
> > -
> > - pci_set_power_state(pdev, PCI_D0);
> > - pci_restore_state(pdev);
> > + struct adapter_info *adap_info = dev_get_drvdata(dev);
> >
> > - if (pci_enable_device(pdev) < 0) {
> > - pch_pci_err(pdev, "pch_i2c_resume:pci_enable_device FAILED\n");
> > - return -EIO;
> > - }
> > -
> > - pci_enable_wake(pdev, PCI_D3hot, 0);
> > + device_wakeup_disable(dev);
>
> It *looks* wrong to disable wakeup in both suspend and resume. I
> think the usual pattern is to enable wakeup in suspend and disable it
> in resume.
>
> But it looks like it's been that way since the driver was added by
> e9bc8fa5df1c ("i2c-eg20t: add driver for Intel EG20T").
>
> If the device doesn't support wakeup, I would not expect the driver to
> mention wakeup at all.
>
> In any case, I think it's the right thing for *this* patch to preserve
> the previous wakeup behavior. Maybe we want a follow-up patch to just
> remove both device_wakeup_disable() calls?
>
> > for (i = 0; i < adap_info->ch_num; i++)
> > pch_i2c_init(&adap_info->pch_data[i]);
> > @@ -908,18 +890,15 @@ static int pch_i2c_resume(struct pci_dev *pdev)
> >
> > return 0;
> > }
> > -#else
> > -#define pch_i2c_suspend NULL
> > -#define pch_i2c_resume NULL
> > -#endif
> > +
> > +static SIMPLE_DEV_PM_OPS(pch_i2c_pm_ops, pch_i2c_suspend, pch_i2c_resume);
> >
> > static struct pci_driver pch_pcidriver = {
> > .name = KBUILD_MODNAME,
> > .id_table = pch_pcidev_id,
> > .probe = pch_i2c_probe,
> > .remove = pch_i2c_remove,
> > - .suspend = pch_i2c_suspend,
> > - .resume = pch_i2c_resume
> > + .driver.pm = &pch_i2c_pm_ops,
> > };
> >
> > module_pci_driver(pch_pcidriver);
> > --
> > 2.27.0
> >