[PATCH v2 07/43] fbdev/deferred-io: Provide get_page hook in struct fb_deferred_io

Thomas Zimmermann
2024-04-10T13:06:02Z

Add a callback for drivers to provide framebuffer pages to fbdev's
deferred-I/O helpers. Implementations need to acquire a reference on
the page before returning it. Returning NULL generates a SIGBUS
signal.

This will be useful for DRM's fbdev emulation with GEM-shmem buffer
objects.

v2:
- fix typo in commit message (Javier)

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
---
drivers/video/fbdev/core/fb_defio.c | 4 ++++
include/linux/fb.h | 1 +
2 files changed, 5 insertions(+)

diff --git a/drivers/video/fbdev/core/fb_defio.c b/drivers/video/fbdev/core/fb_defio.c
index 6e0bbcfdb01b5..51928ff7961a5 100644
--- a/drivers/video/fbdev/core/fb_defio.c
+++ b/drivers/video/fbdev/core/fb_defio.c
@@ -25,9 +25,13 @@

static struct page *fb_deferred_io_get_page(struct fb_info *info, unsigned long offs)
{
+ struct fb_deferred_io *fbdefio = info->fbdefio;
const void *screen_buffer = info->screen_buffer;
struct page *page = NULL;

+ if (fbdefio->get_page)
+ return fbdefio->get_page(info, offs);
+
if (is_vmalloc_addr(screen_buffer + offs))
page = vmalloc_to_page(screen_buffer + offs);
else if (info->fix.smem_start)
diff --git a/include/linux/fb.h b/include/linux/fb.h
index 3417103885e27..4eb6afa93737c 100644
--- a/include/linux/fb.h
+++ b/include/linux/fb.h
@@ -225,6 +225,7 @@ struct fb_deferred_io {
struct mutex lock; /* mutex that protects the pageref list */
struct list_head pagereflist; /* list of pagerefs for touched pages */
/* callback */
+ struct page *(*get_page)(struct fb_info *info, unsigned long offset);
void (*deferred_io)(struct fb_info *info, struct list_head *pagelist);
};
#endif
--
2.44.0