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

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Message-ID: <20200817074634.GD5869@gmail.com>
Date:   Mon, 17 Aug 2020 13:16:34 +0530
From:   Vaibhav Gupta <vaibhavgupta40@...il.com>
To:     Sam Ravnborg <sam@...nborg.org>
Cc:     Bjorn Helgaas <helgaas@...nel.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Bjorn Helgaas <bjorn@...gaas.com>,
        Vaibhav Gupta <vaibhav.varodek@...il.com>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        Paul Mackerras <paulus@...ba.org>,
        Russell King <linux@...linux.org.uk>,
        Andres Salomon <dilinger@...ued.net>,
        Antonino Daplas <adaplas@...il.com>,
        dri-devel@...ts.freedesktop.org, linux-fbdev@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-geode@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-kernel-mentees@...ts.linuxfoundation.org,
        Shuah Khan <skhan@...uxfoundation.org>
Subject: Re: [PATCH v2 09/12] fbdev: i740fb: use generic power management

On Sun, Aug 16, 2020 at 10:24:42PM +0200, Sam Ravnborg wrote:
> 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@...il.com>
> 
> 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
> 
Okay,

Thanks
Vaibhav Gupta
> > ---
> >  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