Call sysfb_disable() from aperture_remove_conflicting_pci_devices() before removing PCI devices. Without, simpledrm can still bind to simple-framebuffer devices after the hardware driver has taken over the hardware. Both drivers interfere with each other and results are undefined.

Reported modesetting errors [1] are shown below.

---- snap ---- rcu: INFO: rcu_sched detected expedited stalls on CPUs/tasks: { 13-.... } 7 jiffies s: 165 root: 0x2000/. rcu: blocking rcu_node structures (internal RCU debug): Task dump for CPU 13: task:X state:R running task stack: 0 pid: 4242 ppid: 4228 flags:0x00000008 Call Trace: <TASK> ? commit_tail+0xd7/0x130 ? drm_atomic_helper_commit+0x126/0x150 ? drm_atomic_commit+0xa4/0xe0 ? drm_plane_get_damage_clips.cold+0x1c/0x1c ? drm_atomic_helper_dirtyfb+0x19e/0x280 ? drm_mode_dirtyfb_ioctl+0x10f/0x1e0 ? drm_mode_getfb2_ioctl+0x2d0/0x2d0 ? drm_ioctl_kernel+0xc4/0x150 ? drm_ioctl+0x246/0x3f0 ? drm_mode_getfb2_ioctl+0x2d0/0x2d0 ? __x64_sys_ioctl+0x91/0xd0 ? do_syscall_64+0x60/0xd0 ? entry_SYSCALL_64_after_hwframe+0x4b/0xb5 </TASK> ... rcu: INFO: rcu_sched detected expedited stalls on CPUs/tasks: { 13-.... } 30 jiffies s: 169 root: 0x2000/. rcu: blocking rcu_node structures (internal RCU debug): Task dump for CPU 13: task:X state:R running task stack: 0 pid: 4242 ppid: 4228 flags:0x0000400e Call Trace: <TASK> ? memcpy_toio+0x76/0xc0 ? memcpy_toio+0x1b/0xc0 ? drm_fb_memcpy_toio+0x76/0xb0 ? drm_fb_blit_toio+0x75/0x2b0 ? simpledrm_simple_display_pipe_update+0x132/0x150 ? drm_atomic_helper_commit_planes+0xb6/0x230 ? drm_atomic_helper_commit_tail+0x44/0x80 ? commit_tail+0xd7/0x130 ? drm_atomic_helper_commit+0x126/0x150 ? drm_atomic_commit+0xa4/0xe0 ? drm_plane_get_damage_clips.cold+0x1c/0x1c ? drm_atomic_helper_dirtyfb+0x19e/0x280 ? drm_mode_dirtyfb_ioctl+0x10f/0x1e0 ? drm_mode_getfb2_ioctl+0x2d0/0x2d0 ? drm_ioctl_kernel+0xc4/0x150 ? drm_ioctl+0x246/0x3f0 ? drm_mode_getfb2_ioctl+0x2d0/0x2d0 ? __x64_sys_ioctl+0x91/0xd0 ? do_syscall_64+0x60/0xd0 ? entry_SYSCALL_64_after_hwframe+0x4b/0xb5 </TASK>

The problem was added by commit 5e0137612430 ("video/aperture: Disable and unregister sysfb devices via aperture helpers") to v6.0.3 and does not exist in the mainline branch.

The mainline commit 5e0137612430 ("video/aperture: Disable and unregister sysfb devices via aperture helpers") has been backported from v6.0-rc1 to stable v6.0.3 from a larger patch series [2] that reworks fbdev framebuffer ownership. The backport misses a change to aperture_remove_conflicting_pci_devices(). Mainline itself is fine, because the function does not exist there as a result of the patch series.

Instead of backporting the whole series, fix the additional function.

v2: * expand justification for this fix (Greg)

Reported-by: Andreas Thalhammer andreas.thalhammer-linux@gmx.net Reported-by: Thorsten Leemhuis regressions@leemhuis.info Signed-off-by: Thomas Zimmermann tzimmermann@suse.de Tested-by: Andreas Thalhammer andreas.thalhammer-linux@gmx.net Fixes: cfecfc98a78d ("video/aperture: Disable and unregister sysfb devices via aperture helpers") Cc: Thomas Zimmermann tzimmermann@suse.de Cc: Javier Martinez Canillas javierm@redhat.com Cc: Zack Rusin zackr@vmware.com Cc: Daniel Vetter daniel.vetter@ffwll.ch Cc: Daniel Vetter daniel@ffwll.ch Cc: Sam Ravnborg sam@ravnborg.org Cc: Helge Deller deller@gmx.de Cc: Alex Deucher alexander.deucher@amd.com Cc: Zhen Lei thunder.leizhen@huawei.com Cc: Changcheng Deng deng.changcheng@zte.com.cn Cc: Maarten Lankhorst maarten.lankhorst@linux.intel.com Cc: Maxime Ripard mripard@kernel.org Cc: dri-devel@lists.freedesktop.org Cc: Sasha Levin sashal@kernel.org Cc: linux-fbdev@vger.kernel.org Cc: stable@vger.kernel.org # v6.0.3+ Link: https://lore.kernel.org/dri-devel/d6afe54b-f8d7-beb2-3609-186e566cbfac@gmx.n... # [1] Link: https://patchwork.freedesktop.org/series/106040/ # [2] --- drivers/video/aperture.c | 11 +++++++++++ 1 file changed, 11 insertions(+)

diff --git a/drivers/video/aperture.c b/drivers/video/aperture.c index d245826a9324..cc6427a091bc 100644 --- a/drivers/video/aperture.c +++ b/drivers/video/aperture.c @@ -338,6 +338,17 @@ int aperture_remove_conflicting_pci_devices(struct pci_dev *pdev, const char *na resource_size_t base, size; int bar, ret;

+ /* + * If a driver asked to unregister a platform device registered by + * sysfb, then can be assumed that this is a driver for a display + * that is set up by the system firmware and has a generic driver. + * + * Drivers for devices that don't have a generic driver will never + * ask for this, so let's assume that a real driver for the display + * was already probed and prevent sysfb to register devices later. + */ + sysfb_disable(); + /* * WARNING: Apparently we must kick fbdev drivers before vgacon, * otherwise the vga fbdev driver falls over.