On Tue, Aug 10, 2021 at 4:36 AM Imre Deak <imre.deak@xxxxxxxxx> wrote:
>
> Hi Kai-Heng, Alex,
>
> could you add your ack if the fix looks ok and you're ok if I push it to
> the i915 tree?
>
Acked-by: Alex Deucher <alexander.deucher@xxxxxxx>
> Thanks,
> Imre
>
> On Mon, Aug 09, 2021 at 04:31:46PM +0300, Imre Deak wrote:
> > Atm the EFI FB platform driver gets a runtime PM reference for the
> > associated GFX PCI device during probing the EFI FB platform device and
> > releases it only when the platform device gets unbound.
> >
> > When fbcon switches to the FB provided by the PCI device's driver (for
> > instance i915/drmfb), the EFI FB will get only unregistered without the
> > EFI FB platform device getting unbound, keeping the runtime PM reference
> > acquired during the platform device probing. This reference will prevent
> > the PCI driver from runtime suspending the device.
> >
> > Fix this by releasing the RPM reference from the EFI FB's destroy hook,
> > called when the FB gets unregistered.
> >
> > While at it assert that pm_runtime_get_sync() didn't fail.
> >
> > v2:
> > - Move pm_runtime_get_sync() before register_framebuffer() to avoid its
> > race wrt. efifb_destroy()->pm_runtime_put(). (Daniel)
> > - Assert that pm_runtime_get_sync() didn't fail.
> > - Clarify commit message wrt. platform/PCI device/driver and driver
> > removal vs. device unbinding.
> >
> > Fixes: a6c0fd3d5a8b ("efifb: Ensure graphics device for efifb stays at PCI D0")
> > Cc: Kai-Heng Feng <kai.heng.feng@xxxxxxxxxxxxx>
> > Cc: Daniel Vetter <daniel.vetter@xxxxxxxx>
> > Reviewed-by: Daniel Vetter <daniel.vetter@xxxxxxxx> (v1)
> > Signed-off-by: Imre Deak <imre.deak@xxxxxxxxx>
> > ---
> > drivers/video/fbdev/efifb.c | 21 ++++++++++++++-------
> > 1 file changed, 14 insertions(+), 7 deletions(-)
> >
> > diff --git a/drivers/video/fbdev/efifb.c b/drivers/video/fbdev/efifb.c
> > index 8ea8f079cde26..edca3703b9640 100644
> > --- a/drivers/video/fbdev/efifb.c
> > +++ b/drivers/video/fbdev/efifb.c
> > @@ -47,6 +47,8 @@ static bool use_bgrt = true;
> > static bool request_mem_succeeded = false;
> > static u64 mem_flags = EFI_MEMORY_WC | EFI_MEMORY_UC;
> >
> > +static struct pci_dev *efifb_pci_dev; /* dev with BAR covering the efifb */
> > +
> > static struct fb_var_screeninfo efifb_defined = {
> > .activate = FB_ACTIVATE_NOW,
> > .height = -1,
> > @@ -243,6 +245,9 @@ static inline void efifb_show_boot_graphics(struct fb_info *info) {}
> >
> > static void efifb_destroy(struct fb_info *info)
> > {
> > + if (efifb_pci_dev)
> > + pm_runtime_put(&efifb_pci_dev->dev);
> > +
> > if (info->screen_base) {
> > if (mem_flags & (EFI_MEMORY_UC | EFI_MEMORY_WC))
> > iounmap(info->screen_base);
> > @@ -333,7 +338,6 @@ ATTRIBUTE_GROUPS(efifb);
> >
> > static bool pci_dev_disabled; /* FB base matches BAR of a disabled device */
> >
> > -static struct pci_dev *efifb_pci_dev; /* dev with BAR covering the efifb */
> > static struct resource *bar_resource;
> > static u64 bar_offset;
> >
> > @@ -569,17 +573,22 @@ static int efifb_probe(struct platform_device *dev)
> > pr_err("efifb: cannot allocate colormap\n");
> > goto err_groups;
> > }
> > +
> > + if (efifb_pci_dev)
> > + WARN_ON(pm_runtime_get_sync(&efifb_pci_dev->dev) < 0);
> > +
> > err = register_framebuffer(info);
> > if (err < 0) {
> > pr_err("efifb: cannot register framebuffer\n");
> > - goto err_fb_dealoc;
> > + goto err_put_rpm_ref;
> > }
> > fb_info(info, "%s frame buffer device\n", info->fix.id);
> > - if (efifb_pci_dev)
> > - pm_runtime_get_sync(&efifb_pci_dev->dev);
> > return 0;
> >
> > -err_fb_dealoc:
> > +err_put_rpm_ref:
> > + if (efifb_pci_dev)
> > + pm_runtime_put(&efifb_pci_dev->dev);
> > +
> > fb_dealloc_cmap(&info->cmap);
> > err_groups:
> > sysfs_remove_groups(&dev->dev.kobj, efifb_groups);
> > @@ -603,8 +612,6 @@ static int efifb_remove(struct platform_device *pdev)
> > unregister_framebuffer(info);
> > sysfs_remove_groups(&pdev->dev.kobj, efifb_groups);
> > framebuffer_release(info);
> > - if (efifb_pci_dev)
> > - pm_runtime_put(&efifb_pci_dev->dev);
> >
> > return 0;
> > }
> > --
> > 2.27.0
> >
