[PATCH] firmware/sysfb: Disable sysfb for firmware buffers with unknown parent

[Alex Deucher]

On Tue, Sep 24, 2024 at 4:58 AM Thomas Zimmermann <tzimmermann at suse.de> wrote:
>
> The sysfb framebuffer handling only operates on graphics devices
> that provide the system's firmware framebuffer. If that device is
> not known, assume that any graphics device has been initialized by
> firmware.
>
> Fixes a problem on i915 where sysfb does not release the firmware
> framebuffer after the native graphics driver loaded.
>
> Reported-by: Borah, Chaitanya Kumar <chaitanya.kumar.borah at intel.com>
> Closes: https://lore.kernel.org/dri-devel/SJ1PR11MB6129EFB8CE63D1EF6D932F94B96F2@SJ1PR11MB6129.namprd11.prod.outlook.com/
> Closes: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/12160
> Signed-off-by: Thomas Zimmermann <tzimmermann at suse.de>
> Fixes: b49420d6a1ae ("video/aperture: optionally match the device in sysfb_disable()")
> Cc: Javier Martinez Canillas <javierm at redhat.com>
> Cc: Thomas Zimmermann <tzimmermann at suse.de>
> Cc: Helge Deller <deller at gmx.de>
> Cc: Sam Ravnborg <sam at ravnborg.org>
> Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
> Cc: Alex Deucher <alexander.deucher at amd.com>
> Cc: dri-devel at lists.freedesktop.org
> Cc: Linux regression tracking (Thorsten Leemhuis) <regressions at leemhuis.info>
> Cc: <stable at vger.kernel.org> # v6.11+

Thanks for fixing this.

Acked-by: Alex Deucher <alexander.deucher at amd.com>

> ---
>  drivers/firmware/sysfb.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/firmware/sysfb.c b/drivers/firmware/sysfb.c
> index 02a07d3d0d40..a3df782fa687 100644
> --- a/drivers/firmware/sysfb.c
> +++ b/drivers/firmware/sysfb.c
> @@ -67,9 +67,11 @@ static bool sysfb_unregister(void)
>  void sysfb_disable(struct device *dev)
>  {
>         struct screen_info *si = &screen_info;
> +       struct device *parent;
>
>         mutex_lock(&disable_lock);
> -       if (!dev || dev == sysfb_parent_dev(si)) {
> +       parent = sysfb_parent_dev(si);
> +       if (!dev || !parent || dev == parent) {
>                 sysfb_unregister();
>                 disabled = true;
>         }
> --
> 2.46.0
>