On Wed, Mar 25, 2020 at 03:43:10PM +0100, Hans de Goede wrote:
> The vboxvideo driver is missing a call to remove conflicting framebuffers.
>
> Surprisingly, when using legacy BIOS booting this does not really cause
> any issues. But when using UEFI to boot the VM then plymouth will draw
> on both the efifb /dev/fb0 and /dev/drm/card0 (which has registered
> /dev/fb1 as fbdev emulation).
>
> VirtualBox will actual display the output of both devices (I guess it is
> showing whatever was drawn last), this causes weird artifacts because of
> pitch issues in the efifb when the VM window is not sized at 1024x768
> (the window will resize to its last size once the vboxvideo driver loads,
> changing the pitch).
>
> Adding the missing drm_fb_helper_remove_conflicting_pci_framebuffers()
> call fixes this.
>
> Cc: stable@xxxxxxxxxxxxxxx
> Fixes: 2695eae1f6d3 ("drm/vboxvideo: Switch to generic fbdev emulation")
> Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
> ---
> drivers/gpu/drm/vboxvideo/vbox_drv.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/drivers/gpu/drm/vboxvideo/vbox_drv.c b/drivers/gpu/drm/vboxvideo/vbox_drv.c
> index 8512d970a09f..261255085918 100644
> --- a/drivers/gpu/drm/vboxvideo/vbox_drv.c
> +++ b/drivers/gpu/drm/vboxvideo/vbox_drv.c
> @@ -76,6 +76,10 @@ static int vbox_pci_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
> if (ret)
> goto err_mode_fini;
>
> + ret = drm_fb_helper_remove_conflicting_pci_framebuffers(pdev, "vboxvideodrmfb");
> + if (ret)
> + goto err_irq_fini;
To avoid transient issues this should be done as early as possible,
definitely before the drm driver starts to touch the "hw". With that
Reviewed-by: Daniel Vetter <daniel.vetter@xxxxxxxx>
I do wonder though why the automatic removal of conflicting framebuffers
doesn't work, fbdev should already do that from register_framebuffer(),
which is called somewhere in drm_fbdev_generic_setup (after a few layers).
Did you check why the two framebuffers don't conflict, and why the uefi
one doesn't get thrown out?
-Daniel
> +
> ret = drm_fbdev_generic_setup(&vbox->ddev, 32);
> if (ret)
> goto err_irq_fini;
> --
> 2.26.0.rc2
>
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--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
