Re: [PATCH v2 09/12] fbdev: i740fb: use generic power management

From: Sam Ravnborg
Date: Sun Aug 16 2020 - 16:25:09 EST


Hi Vaibhav

On Tue, Aug 11, 2020 at 12:27:20AM +0530, Vaibhav Gupta wrote:
> Drivers should do only device-specific jobs. But in general, drivers using
> legacy PCI PM framework for .suspend()/.resume() have to manage many PCI
> PM-related tasks themselves which can be done by PCI Core itself. This
> brings extra load on the driver and it directly calls PCI helper functions
> to handle them.
>
> Switch to the new generic framework by updating function signatures and
> define a "struct dev_pm_ops" variable to bind PM callbacks. Also, remove
> unnecessary calls to the PCI Helper functions along with the legacy
> .suspend & .resume bindings.
>
> Signed-off-by: Vaibhav Gupta <vaibhavgupta40@xxxxxxxxx>

I several of the drivers I briefly looked at a new set of helpers were
introduced for the different types of pm actions.
They then called a more generic function that uses the passes
enumeration to decide what to do.

But in this driver the test "state.event == PM_EVENT_FREEZE" is dropped
and there is no freeze operation.
Please explain this change so the reader is not left wondering.

Sam

> ---
> drivers/video/fbdev/i740fb.c | 40 +++++++++++++++---------------------
> 1 file changed, 16 insertions(+), 24 deletions(-)
>
> diff --git a/drivers/video/fbdev/i740fb.c b/drivers/video/fbdev/i740fb.c
> index c65ec7386e87..8d7f06fc8a5a 100644
> --- a/drivers/video/fbdev/i740fb.c
> +++ b/drivers/video/fbdev/i740fb.c
> @@ -1175,16 +1175,11 @@ static void i740fb_remove(struct pci_dev *dev)
> }
> }
>
> -#ifdef CONFIG_PM
> -static int i740fb_suspend(struct pci_dev *dev, pm_message_t state)
> +static int __maybe_unused i740fb_suspend(struct device *dev)
> {
> - struct fb_info *info = pci_get_drvdata(dev);
> + struct fb_info *info = dev_get_drvdata(dev);
> struct i740fb_par *par = info->par;
>
> - /* don't disable console during hibernation and wakeup from it */
> - if (state.event == PM_EVENT_FREEZE || state.event == PM_EVENT_PRETHAW)
> - return 0;
> -
> console_lock();
> mutex_lock(&(par->open_lock));
>
> @@ -1197,19 +1192,15 @@ static int i740fb_suspend(struct pci_dev *dev, pm_message_t state)
>
> fb_set_suspend(info, 1);
>
> - pci_save_state(dev);
> - pci_disable_device(dev);
> - pci_set_power_state(dev, pci_choose_state(dev, state));
> -
> mutex_unlock(&(par->open_lock));
> console_unlock();
>
> return 0;
> }
>
> -static int i740fb_resume(struct pci_dev *dev)
> +static int __maybe_unused i740fb_resume(struct device *dev)
> {
> - struct fb_info *info = pci_get_drvdata(dev);
> + struct fb_info *info = dev_get_drvdata(dev);
> struct i740fb_par *par = info->par;
>
> console_lock();
> @@ -1218,11 +1209,6 @@ static int i740fb_resume(struct pci_dev *dev)
> if (par->ref_count == 0)
> goto fail;
>
> - pci_set_power_state(dev, PCI_D0);
> - pci_restore_state(dev);
> - if (pci_enable_device(dev))
> - goto fail;
> -
> i740fb_set_par(info);
> fb_set_suspend(info, 0);
>
> @@ -1231,10 +1217,17 @@ static int i740fb_resume(struct pci_dev *dev)
> console_unlock();
> return 0;
> }
> -#else
> -#define i740fb_suspend NULL
> -#define i740fb_resume NULL
> -#endif /* CONFIG_PM */
> +
> +static const struct dev_pm_ops i740fb_pm_ops = {
> +#ifdef CONFIG_PM_SLEEP
> + .suspend = i740fb_suspend,
> + .resume = i740fb_resume,
> + .freeze = NULL,
> + .thaw = i740fb_resume,
> + .poweroff = i740fb_suspend,
> + .restore = i740fb_resume,
> +#endif /* CONFIG_PM_SLEEP */
> +};
>
> #define I740_ID_PCI 0x00d1
> #define I740_ID_AGP 0x7800
> @@ -1251,8 +1244,7 @@ static struct pci_driver i740fb_driver = {
> .id_table = i740fb_id_table,
> .probe = i740fb_probe,
> .remove = i740fb_remove,
> - .suspend = i740fb_suspend,
> - .resume = i740fb_resume,
> + .driver.pm = &i740fb_pm_ops,
> };
>
> #ifndef MODULE
> --
> 2.27.0