Re: [PATCH 11/11] video/aperture: Only remove sysfb on the default vga pci device

[Thomas Zimmermann <tzimmermann@xxxxxxx>]

Hi

Am 11.01.23 um 20:21 schrieb Aaron Plattner:
> On 1/11/23 8:58 AM, Javier Martinez Canillas wrote:
> > Hello Daniel,
> >
> > On 1/11/23 16:41, Daniel Vetter wrote:
> > > This fixes a regression introduced by ee7a69aa38d8 ("fbdev: Disable
> > > sysfb device registration when removing conflicting FBs"), where we
> > > remove the sysfb when loading a driver for an unrelated pci device,
> > > resulting in the user loosing their efifb console or similar.
> > >
> > > Note that in practice this only is a problem with the nvidia blob,
> > > because that's the only gpu driver people might install which does not
> > > come with an fbdev driver of it's own. For everyone else the real gpu
> > > driver will restor a working console.
> >
> > restore
> >
> > > Also note that in the referenced bug there's confusion that this same
> > > bug also happens on amdgpu. But that was just another amdgpu specific
> > > regression, which just happened to happen at roughly the same time and
> > > with the same user-observable symptons. That bug is fixed now, see
> >
> > symptoms
> >
> > > https://bugzilla.kernel.org/show_bug.cgi?id=216331#c15
> > >
> > > For the above reasons the cc: stable is just notionally, this patch
> > > will need a backport and that's up to nvidia if they care enough.
> >
> > Maybe adding a Fixes: ee7a69aa38d8 tag here too ?
> >
> > > References: https://bugzilla.kernel.org/show_bug.cgi?id=216303#c28
> > > Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxxx>
> > > Cc: Aaron Plattner <aplattner@xxxxxxxxxx>
> > > Cc: Javier Martinez Canillas <javierm@xxxxxxxxxx>
> > > Cc: Thomas Zimmermann <tzimmermann@xxxxxxx>
> > > Cc: Helge Deller <deller@xxxxxx>
> > > Cc: Sam Ravnborg <sam@xxxxxxxxxxxx>
> > > Cc: Alex Deucher <alexander.deucher@xxxxxxx>
> > > Cc: <stable@xxxxxxxxxxxxxxx> # v5.19+ (if someone else does the 
> > > backport)
> > > ---
> > >   drivers/video/aperture.c | 7 ++++---
> > >   1 file changed, 4 insertions(+), 3 deletions(-)
> > >
> > > diff --git a/drivers/video/aperture.c b/drivers/video/aperture.c
> > > index ba565515480d..a1821d369bb1 100644
> > > --- a/drivers/video/aperture.c
> > > +++ b/drivers/video/aperture.c
> > > @@ -321,15 +321,16 @@ int 
> > > aperture_remove_conflicting_pci_devices(struct pci_dev *pdev, const 
> > > char *na
> > >       primary = pdev == vga_default_device();
> > > +    if (primary)
> > > +        sysfb_disable();
> > > +
> > >       for (bar = 0; bar < PCI_STD_NUM_BARS; ++bar) {
> > >           if (!(pci_resource_flags(pdev, bar) & IORESOURCE_MEM))
> > >               continue;
> > >           base = pci_resource_start(pdev, bar);
> > >           size = pci_resource_len(pdev, bar);
> > > -        ret = aperture_remove_conflicting_devices(base, size, name);
> > > -        if (ret)
> > > -            return ret;
> > > +        aperture_detach_devices(base, size);
> >
> > Maybe mention in the commit message that you are doing this change, 
> > something like:
> >
> > "Instead of calling aperture_remove_conflicting_devices() to remove 
> > the conflicting
> > devices, just call to aperture_detach_devices() to detach the device 
> > that matches
> > the same PCI BAR / aperture range. Since the former is just a wrapper 
> > of the latter
> > plus a sysfb_disable() call, and now that's done in this function but 
> > only for the
> > primary devices"
> >
> > Patch looks good to me:
> >
> > Reviewed-by: Javier Martinez Canillas <javierm@xxxxxxxxxx>
>
> Thanks Daniel and Javier!
>
> I wasn't able to reproduce the original problem on my hybrid laptop 
> since it refuses to boot with the console on an external display, but I 
> was able to reproduce it by switching the configuration around: booting 
> with i915.modeset=0 and with an experimental version of nvidia-drm that 
> registers a framebuffer console. I verified that loading nvidia-drm 

Thank you for testing.

One thing I'd like to note is that using DRM's fbdev emulation is the 
correct way to support a console. Nvidia-drm's current approach of 
utilizing efifb is fragile and requires workarounds from distributions 
(at least here at SUSE). Steps towards fbdev emulation are much appreciated.

Best regards
Thomas

> breaks the efi-firmware framebuffer on Intel on Arch's 
> linux-6.1.4-arch1-1 kernel and that applying this patch series fixes it. So
>
> Tested-by: Aaron Plattner <aplattner@xxxxxxxxxx>
>
> FWIW, the bug ought to be reproducible with i915.modeset=0 + any other 
> drm driver that registers a framebuffer.
>
> -- Aaron

--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Ivo Totev

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