From: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> [ Upstream commit 840fe258332544aa7321921e1723d37b772af7a9 ] As the ht16k33 frame buffer sub-driver does not register an fb_ops.fb_blank() handler, blanking does not work: $ echo 1 > /sys/class/graphics/fb0/blank sh: write error: Invalid argument Fix this by providing a handler that always returns zero, to make sure blank events will be sent to the actual device handling the backlight. Reported-by: Robin van der Gracht <robin@xxxxxxxxxxx> Suggested-by: Robin van der Gracht <robin@xxxxxxxxxxx> Fixes: 8992da44c6805d53 ("auxdisplay: ht16k33: Driver for LED controller") Signed-off-by: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> Signed-off-by: Miguel Ojeda <ojeda@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- drivers/auxdisplay/ht16k33.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/drivers/auxdisplay/ht16k33.c b/drivers/auxdisplay/ht16k33.c index 2b630e194570f..ed58083499907 100644 --- a/drivers/auxdisplay/ht16k33.c +++ b/drivers/auxdisplay/ht16k33.c @@ -219,6 +219,15 @@ static const struct backlight_ops ht16k33_bl_ops = { .check_fb = ht16k33_bl_check_fb, }; +/* + * Blank events will be passed to the actual device handling the backlight when + * we return zero here. + */ +static int ht16k33_blank(int blank, struct fb_info *info) +{ + return 0; +} + static int ht16k33_mmap(struct fb_info *info, struct vm_area_struct *vma) { struct ht16k33_priv *priv = info->par; @@ -231,6 +240,7 @@ static const struct fb_ops ht16k33_fb_ops = { .owner = THIS_MODULE, .fb_read = fb_sys_read, .fb_write = fb_sys_write, + .fb_blank = ht16k33_blank, .fb_fillrect = sys_fillrect, .fb_copyarea = sys_copyarea, .fb_imageblit = sys_imageblit, -- 2.33.0