From: Javier Martinez Canillas Date: Tue, 7 Jun 2022 18:23:36 +0000 (+0200) Subject: fbdev: Disable sysfb device registration when removing conflicting FBs X-Git-Tag: v6.6.17~6062^2^2~101 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=ee7a69aa38d87a3bbced7b8245c732c05ed0c6ec;p=platform%2Fkernel%2Flinux-rpi.git fbdev: Disable sysfb device registration when removing conflicting FBs The platform devices registered by sysfb match with firmware-based DRM or fbdev drivers, that are used to have early graphics using a framebuffer provided by the system firmware. DRM or fbdev drivers later are probed and remove conflicting framebuffers, leading to these platform devices for generic drivers to be unregistered. But the current solution has a race, since the sysfb_init() function could be called after a DRM or fbdev driver is probed and request to unregister the devices for drivers with conflicting framebuffes. To prevent this, disable any future sysfb platform device registration by calling sysfb_disable(), if a driver requests to remove the conflicting framebuffers. Suggested-by: Daniel Vetter Signed-off-by: Javier Martinez Canillas Reviewed-by: Daniel Vetter Link: https://patchwork.freedesktop.org/patch/msgid/20220607182338.344270-4-javierm@redhat.com --- diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c index afa2863..8afc453 100644 --- a/drivers/video/fbdev/core/fbmem.c +++ b/drivers/video/fbdev/core/fbmem.c @@ -19,6 +19,7 @@ #include #include #include +#include #include #include #include @@ -1752,6 +1753,17 @@ int remove_conflicting_framebuffers(struct apertures_struct *a, do_free = true; } + /* + * 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(); + mutex_lock(®istration_lock); do_remove_conflicting_framebuffers(a, name, primary); mutex_unlock(®istration_lock);