@@ -1762,6 +1762,53 @@ int remove_conflicting_framebuffers(struct apertures_struct *a,
}
EXPORT_SYMBOL(remove_conflicting_framebuffers);
+/**
+ * is_firmware_framebuffer - detect if firmware-configured framebuffer matches
+ * @a: memory range, users of which are to be checked
+ *
+ * This function checks framebuffer devices (initialized by firmware/bootloader)
+ * which use memory range described by @a. If @a matchesm the function returns
+ * true, otherwise false.
+ */
+bool is_firmware_framebuffer(struct apertures_struct *a)
+{
+ bool do_free = false;
+ bool found = false;
+ int i;
+
+ if (!a) {
+ a = alloc_apertures(1);
+ if (!a)
+ return false;
+
+ a->ranges[0].base = 0;
+ a->ranges[0].size = ~0;
+ do_free = true;
+ }
+
+ mutex_lock(®istration_lock);
+ /* check all firmware fbs and kick off if the base addr overlaps */
+ for_each_registered_fb(i) {
+ struct apertures_struct *gen_aper;
+
+ if (!(registered_fb[i]->flags & FBINFO_MISC_FIRMWARE))
+ continue;
+
+ gen_aper = registered_fb[i]->apertures;
+ if (fb_do_apertures_overlap(gen_aper, a)) {
+ found = true;
+ break;
+ }
+ }
+ mutex_unlock(®istration_lock);
+
+ if (do_free)
+ kfree(a);
+
+ return found;
+}
+EXPORT_SYMBOL(is_firmware_framebuffer);
+
/**
* remove_conflicting_pci_framebuffers - remove firmware-configured framebuffers for PCI devices
* @pdev: PCI device
@@ -610,6 +610,7 @@ extern int remove_conflicting_pci_framebuffers(struct pci_dev *pdev,
const char *name);
extern int remove_conflicting_framebuffers(struct apertures_struct *a,
const char *name, bool primary);
+extern bool is_firmware_framebuffer(struct apertures_struct *a);
extern int fb_prepare_logo(struct fb_info *fb_info, int rotate);
extern int fb_show_logo(struct fb_info *fb_info, int rotate);
extern char* fb_get_buffer_offset(struct fb_info *info, struct fb_pixmap *buf, u32 size);
Add a function for drivers to check if the a firmware initialized fb is corresponds to their aperture. This allows drivers to check if the device corresponds to what the firmware set up as the display device. Bug: https://bugzilla.kernel.org/show_bug.cgi?id=215203 Bug: https://gitlab.freedesktop.org/drm/amd/-/issues/1840 Signed-off-by: Alex Deucher <alexander.deucher@amd.com> --- drivers/video/fbdev/core/fbmem.c | 47 ++++++++++++++++++++++++++++++++ include/linux/fb.h | 1 + 2 files changed, 48 insertions(+)