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Message-ID: <20200817074501.GC5869@gmail.com>
Date: Mon, 17 Aug 2020 13:15:01 +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 01/12] fbdev: gxfb: use generic power management
On Sun, Aug 16, 2020 at 10:16:01PM +0200, Sam Ravnborg wrote:
> Hi Vaibhav
>
> On Tue, Aug 11, 2020 at 12:27:12AM +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.
> >
> > Although the gxfb driver does not have that extra load,
> Sorry, but I am lost here.
> If this drivers does not have the extra load that you describe here then
> I really cannot see why it is relevant for this driver to describe it.
>
> This is a seldomly touched driver - so it helps if the changelog when we
> finally touch the code is easy to parse.
>
> > we should switch to
> > the new generic framework by updating function signatures and define a
> > "struct dev_pm_ops" variable to bind PM callbacks so that we can remove
> > the legacy .suspend & .resume bindings.
> This part matches the patch - good.
>
> > Additionally, this helps us to
> > remove the unnecessary call to gxfb_suspend() in the event of Freeze and
> > Hibernate, as the function does nothing in their case.
> What I think you are explaining above is that the pci pm support
> will only call the suspend operation in case of suspend, so the
> state.event == PM_EVENT_SUSPEND can be dropped in gxfb_suspend().
>
> For reference later I would prefer that this is explained a bit
> more explicit - not that the changelog needs update anyway.
> >
> > Signed-off-by: Vaibhav Gupta <vaibhavgupta40@...il.com>
> Patch looks good, but please give the changelog one more go.
> I have not checked other patches - but I assume they would benefit
> from a similar clarification.
>
> Sam
>
Hello Sam
I will do the changes as suggested.
Thanks
Vaibhav Gupta
> > ---
> > drivers/video/fbdev/geode/gxfb.h | 5 ----
> > drivers/video/fbdev/geode/gxfb_core.c | 36 ++++++++++++++------------
> > drivers/video/fbdev/geode/suspend_gx.c | 4 ---
> > 3 files changed, 20 insertions(+), 25 deletions(-)
> >
> > diff --git a/drivers/video/fbdev/geode/gxfb.h b/drivers/video/fbdev/geode/gxfb.h
> > index d2e9c5c8e294..792c111c21e4 100644
> > --- a/drivers/video/fbdev/geode/gxfb.h
> > +++ b/drivers/video/fbdev/geode/gxfb.h
> > @@ -21,7 +21,6 @@ struct gxfb_par {
> > void __iomem *dc_regs;
> > void __iomem *vid_regs;
> > void __iomem *gp_regs;
> > -#ifdef CONFIG_PM
> > int powered_down;
> >
> > /* register state, for power management functionality */
> > @@ -36,7 +35,6 @@ struct gxfb_par {
> > uint64_t fp[FP_REG_COUNT];
> >
> > uint32_t pal[DC_PAL_COUNT];
> > -#endif
> > };
> >
> > unsigned int gx_frame_buffer_size(void);
> > @@ -49,11 +47,8 @@ void gx_set_dclk_frequency(struct fb_info *info);
> > void gx_configure_display(struct fb_info *info);
> > int gx_blank_display(struct fb_info *info, int blank_mode);
> >
> > -#ifdef CONFIG_PM
> > int gx_powerdown(struct fb_info *info);
> > int gx_powerup(struct fb_info *info);
> > -#endif
> > -
> >
> > /* Graphics Processor registers (table 6-23 from the data book) */
> > enum gp_registers {
> > diff --git a/drivers/video/fbdev/geode/gxfb_core.c b/drivers/video/fbdev/geode/gxfb_core.c
> > index d38a148d4746..44089b331f91 100644
> > --- a/drivers/video/fbdev/geode/gxfb_core.c
> > +++ b/drivers/video/fbdev/geode/gxfb_core.c
> > @@ -322,17 +322,14 @@ static struct fb_info *gxfb_init_fbinfo(struct device *dev)
> > return info;
> > }
> >
> > -#ifdef CONFIG_PM
> > -static int gxfb_suspend(struct pci_dev *pdev, pm_message_t state)
> > +static int __maybe_unused gxfb_suspend(struct device *dev)
> > {
> > - struct fb_info *info = pci_get_drvdata(pdev);
> > + struct fb_info *info = dev_get_drvdata(dev);
> >
> > - if (state.event == PM_EVENT_SUSPEND) {
> > - console_lock();
> > - gx_powerdown(info);
> > - fb_set_suspend(info, 1);
> > - console_unlock();
> > - }
> > + console_lock();
> > + gx_powerdown(info);
> > + fb_set_suspend(info, 1);
> > + console_unlock();
> >
> > /* there's no point in setting PCI states; we emulate PCI, so
> > * we don't end up getting power savings anyways */
> > @@ -340,9 +337,9 @@ static int gxfb_suspend(struct pci_dev *pdev, pm_message_t state)
> > return 0;
> > }
> >
> > -static int gxfb_resume(struct pci_dev *pdev)
> > +static int __maybe_unused gxfb_resume(struct device *dev)
> > {
> > - struct fb_info *info = pci_get_drvdata(pdev);
> > + struct fb_info *info = dev_get_drvdata(dev);
> > int ret;
> >
> > console_lock();
> > @@ -356,7 +353,6 @@ static int gxfb_resume(struct pci_dev *pdev)
> > console_unlock();
> > return 0;
> > }
> > -#endif
> >
> > static int gxfb_probe(struct pci_dev *pdev, const struct pci_device_id *id)
> > {
> > @@ -467,15 +463,23 @@ static const struct pci_device_id gxfb_id_table[] = {
> >
> > MODULE_DEVICE_TABLE(pci, gxfb_id_table);
> >
> > +static const struct dev_pm_ops gxfb_pm_ops = {
> > +#ifdef CONFIG_PM_SLEEP
> > + .suspend = gxfb_suspend,
> > + .resume = gxfb_resume,
> > + .freeze = NULL,
> > + .thaw = gxfb_resume,
> > + .poweroff = NULL,
> > + .restore = gxfb_resume,
> > +#endif
> > +};
> > +
> > static struct pci_driver gxfb_driver = {
> > .name = "gxfb",
> > .id_table = gxfb_id_table,
> > .probe = gxfb_probe,
> > .remove = gxfb_remove,
> > -#ifdef CONFIG_PM
> > - .suspend = gxfb_suspend,
> > - .resume = gxfb_resume,
> > -#endif
> > + .driver.pm = &gxfb_pm_ops,
> > };
> >
> > #ifndef MODULE
> > diff --git a/drivers/video/fbdev/geode/suspend_gx.c b/drivers/video/fbdev/geode/suspend_gx.c
> > index 1110a527c35c..8c49d4e98772 100644
> > --- a/drivers/video/fbdev/geode/suspend_gx.c
> > +++ b/drivers/video/fbdev/geode/suspend_gx.c
> > @@ -11,8 +11,6 @@
> >
> > #include "gxfb.h"
> >
> > -#ifdef CONFIG_PM
> > -
> > static void gx_save_regs(struct gxfb_par *par)
> > {
> > int i;
> > @@ -259,5 +257,3 @@ int gx_powerup(struct fb_info *info)
> > par->powered_down = 0;
> > return 0;
> > }
> > -
> > -#endif
> > --
> > 2.27.0
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