[PATCH 5.14 702/849] auxdisplay: ht16k33: Fix frame buffer device blanking

Greg Kroah-Hartman
2021-11-15T23:16:07Z

From: Geert Uytterhoeven <geert@linux-m68k.org>

[ 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>
---
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