Re: [PATCH v2 2/2] i2c: eg20t: use generic power management

Bjorn Helgaas
2020-08-07T20:23:25Z

[+cc Jean for i801 question below]

On Thu, Aug 06, 2020 at 01:06:16AM +0530, Vaibhav Gupta wrote:
> Drivers using legacy power management .suspen()/.resume() callbacks
> have to manage PCI states and device's PM states themselves. They also
> need to take care of standard configuration registers.
>
> Switch to generic power management framework using a single
> "struct dev_pm_ops" variable to take the unnecessary load from the driver.
> This also avoids the need for the driver to directly call most of the PCI
> helper functions and device power state control functions, as through
> the generic framework PCI Core takes care of the necessary operations,
> and drivers are required to do only device-specific jobs.
>
> Signed-off-by: Vaibhav Gupta <vaibhavgupta40@gmail.com>

s/.suspen/.suspend/ above

These both look right to me.

Reviewed-by: Bjorn Helgaas <bhelgaas@google.com>

Looking at neighboring drivers, it looks like some already use generic
PM but have unnecessary PCI code, e.g., amd_mp2_pci_suspend().
Probably already on your list.

Also, i801_suspend() looks suspicious because it writes SMBHSTCFG, but
I don't see anything corresponding in i801_resume().

> ---
> drivers/i2c/busses/i2c-eg20t.c | 36 +++++++---------------------------
> 1 file changed, 7 insertions(+), 29 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-eg20t.c b/drivers/i2c/busses/i2c-eg20t.c
> index eb41de22d461..843b31a0f752 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);
> void __iomem *p = adap_info->pch_data[0].pch_base_address;
>
> @@ -872,31 +871,13 @@ 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_disable_device(pdev);
> - pci_set_power_state(pdev, pci_choose_state(pdev, state));
> -
> 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);
> -
> - if (pci_enable_device(pdev) < 0) {
> - pch_pci_err(pdev, "pch_i2c_resume:pci_enable_device FAILED\n");
> - return -EIO;
> - }
> + struct adapter_info *adap_info = dev_get_drvdata(dev);
>
> for (i = 0; i < adap_info->ch_num; i++)
> pch_i2c_init(&adap_info->pch_data[i]);
> @@ -905,18 +886,15 @@ 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
>