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Message-ID: <20200816201601.GA1426650@ravnborg.org>
Date: Sun, 16 Aug 2020 22:16:01 +0200
From: Sam Ravnborg <sam@...nborg.org>
To: Vaibhav Gupta <vaibhavgupta40@...il.com>
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
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
> ---
> 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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