Re: [PATCH v1 01/12] fbdev: gxfb: use generic power management

From: Vaibhav Gupta
Date: Mon Aug 10 2020 - 14:00:54 EST

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In reply to: Sam Ravnborg: "Re: [PATCH v1 01/12] fbdev: gxfb: use generic power management"
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On Mon, Aug 10, 2020 at 06:54:58PM +0200, Sam Ravnborg wrote:
> Hi Vaibhav
> On Mon, Aug 10, 2020 at 03:09:48PM +0530, Vaibhav Gupta wrote:
> > On Sat, Aug 08, 2020 at 01:17:46PM +0200, Sam Ravnborg wrote:
> > > Hi Vaibhav
> > >
> > > On Wed, Aug 05, 2020 at 11:37:11PM +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."
> > > - I do not parse the above - I cannot see what load is removed.
> > > But the code is simpler which is fine. The drawback is that we now
> > > always link in the suspend_gx functions but hopefultl the linker drops
> > > them later.
> > >
> > > > 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.
> > > Again, I do not see what calles are removed.
> > > A single check for the state is dropped - anything else?
> > >
> > Yeah, the commit messages are bit misleading, I have modified them.
> > > >
> > > > Signed-off-by: Vaibhav Gupta <vaibhavgupta40@xxxxxxxxx>
> > > > ---
> > > > 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);
> > > I do not see any dev_set_drvdata() so I guess we get a NULL pointer
> > > here which is not intended.
> > > Adding a dev_set_data() to gxfb_probe() would do the trick.
> > >
> > gxfb_probe() invokes pci_set_drvdata(pdev, info) which in turn calls
> > dev_set_drvdata(&pdev->dev, data). Adding dev_get_drvdata() will be redundant.
> OK, not obvious but you are right that calling dev_get_drvdata() would
> be redundant and no need.
> There is a pci_get_drvdata() user left so we cannot just skip it and use
> the dev_set_drvdata() direct.
>
> >
> > > >
> > > > - 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
> > > > +};
> > > Can we use SET_SYSTEM_SLEEP_PM_OPS here?
> > > .freeze will be assigned gxfb_suspend, but gxfb_suspend will anyway be
> > > called as far as I read the code.
> > > Likewise for poweroff.
> > >
> > Earlier, gxfb_suspend() performed each operation just for suspend event.
> > And as it was legacy code, it was invoked by pci_legacy_suspend() for
> > pci_pm_suspend(), pci_pm_freeze() and pci_pm_poweroff().
> > Thus, the code was wrapped inside "if" container:
> > if (state.event == PM_EVENT_SUSPEND) { }
> >
> > After binding it with dev_pm_ops variable, pm->suspend() is invoked by just
> > pci_pm_suspend() which is required.
> >
> > So I removed the "if" container and bind the callback with pm->suspend pointer
> > only.
> Looking at platform.c I got the impression that freeze() would call
> pci_legacy_suspend() anyway - but I may have missind something.
> So I guess this is OK then.
>
> I look forward for next revision with updated changelogs.
Hello Sam,

Yeah, I have updated the logs, will be sending the v2 soon. :)

Thanks
Vaibhav Gupta
>
> Sam
> >
> > Using SET_SYSTEM_PM_OPS will bring back the extra step of invoking gxfb_suspend()
> > for freeze and poweroff, even though the function will do nothing in that case.
> >
> > Vaibhav Gupta
> > > Sam
> > >
> > > > +
> > > > 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
> > > >
> > > > _______________________________________________
> > > > dri-devel mailing list
> > > > dri-devel@xxxxxxxxxxxxxxxxxxxxx
> > > > https://lists.freedesktop.org/mailman/listinfo/dri-devel

Next message: David Sterba: "Re: [PATCH 4.19 09/56] btrfs: inode: Verify inode mode to avoid NULL pointer dereference"
Previous message: Sumera Priyadarsini: "[PATCH v3] documentation: coccinelle: Improve command example for make C={1,2}"
In reply to: Sam Ravnborg: "Re: [PATCH v1 01/12] fbdev: gxfb: use generic power management"
Next in thread: Vaibhav Gupta: "[PATCH v2 00/12] video: fbdev: use generic power management"
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