auxdisplay: ht16k33: Fix frame buffer device blanking

[ 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@protonic.nl>
Suggested-by: Robin van der Gracht <robin@protonic.nl>
Fixes: 8992da44c6805d53 ("auxdisplay: ht16k33: Driver for LED controller")
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/auxdisplay/ht16k33.c b/drivers/auxdisplay/ht16k33.c
index e3c8f355f9a622b23543ebc9952b6f0a0a156bff..f35b7ff29efd28f51f7081ab838050888778df0a 100644 (file)
--- a/drivers/auxdisplay/ht16k33.c
+++ b/drivers/auxdisplay/ht16k33.c
@@ -227,6 +227,15 @@ 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;
@@ -239,6 +248,7 @@ static 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,