Hi Thomas, > diff --git a/drivers/video/fbdev/core/fb_defio.c b/drivers/video/fbdev/core/fb_defio.c > index 6aaf6d0abf39..6924d489a289 100644 > --- a/drivers/video/fbdev/core/fb_defio.c > +++ b/drivers/video/fbdev/core/fb_defio.c > @@ -181,6 +181,7 @@ int fb_deferred_io_mmap(struct fb_info *info, struct vm_area_struct *vma) > vma->vm_private_data = info; > return 0; > } > +EXPORT_SYMBOL_GPL(fb_deferred_io_mmap); > > /* workqueue callback */ > static void fb_deferred_io_work(struct work_struct *work) > diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c > index 84427470367b..52440e3f8f69 100644 > --- a/drivers/video/fbdev/core/fbmem.c > +++ b/drivers/video/fbdev/core/fbmem.c > @@ -1334,7 +1334,6 @@ static int > fb_mmap(struct file *file, struct vm_area_struct * vma) > { > struct fb_info *info = file_fb_info(file); > - int (*fb_mmap_fn)(struct fb_info *info, struct vm_area_struct *vma); > unsigned long mmio_pgoff; > unsigned long start; > u32 len; > @@ -1343,14 +1342,7 @@ fb_mmap(struct file *file, struct vm_area_struct * vma) > return -ENODEV; > mutex_lock(&info->mm_lock); > > - fb_mmap_fn = info->fbops->fb_mmap; > - > -#if IS_ENABLED(CONFIG_FB_DEFERRED_IO) > - if (info->fbdefio) > - fb_mmap_fn = fb_deferred_io_mmap; > -#endif > - > - if (fb_mmap_fn) { > + if (info->fbops->fb_mmap) { > int res; > > /* > @@ -1358,11 +1350,18 @@ fb_mmap(struct file *file, struct vm_area_struct * vma) > * SME protection is removed ahead of the call > */ > vma->vm_page_prot = pgprot_decrypted(vma->vm_page_prot); > - res = fb_mmap_fn(info, vma); > + res = info->fbops->fb_mmap(info, vma); > mutex_unlock(&info->mm_lock); > return res; > } > > + /* > + * FB deferred I/O wants you to handle mmap in your drivers. At a > + * minimum, point struct fb_ops.fb_mmap to fb_deferred_io_mmap(). > + */ > + if (dev_WARN_ONCE(info->dev, info->fbdefio, "fbdev mmap not set up for defered I/O.\n")) > + return -ENODEV; > + If not configured - then why not just call fb_deferred_io_mmap(), as this seems to be the default implementation anyway. Then drivers that needs it can override - and the rest fallback to the default. Sam