[PATCH 2/2] backlight: aw99706: Validate all DT property values consistently

[Junjie Cao <junjie.cao@linux.dev>]

The lookup helpers for dim-mode and ramp-ctl take a shortcut when
lookup_tbl is NULL: they accept any u32 value without range-checking
and return success unconditionally. Out-of-range values get silently
truncated by regmap_update_bits instead of triggering the dev_warn +
default-fallback path that the other properties use.

Add a field-width check for the NULL-table case so that values
exceeding the register field maximum are rejected the same way a
table-lookup miss is.

While here, also switch the error returns to -EINVAL for consistency.

Signed-off-by: Junjie Cao <junjie.cao@linux.dev>
---
 drivers/video/backlight/aw99706.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/drivers/video/backlight/aw99706.c b/drivers/video/backlight/aw99706.c
index abacf5a6c8ae..a00a4144f160 100644
--- a/drivers/video/backlight/aw99706.c
+++ b/drivers/video/backlight/aw99706.c
@@ -94,6 +94,8 @@ static int aw99706_dt_property_lookup(const struct aw99706_dt_prop *prop,
 	int i;
 
 	if (!prop->lookup_tbl) {
+		if (dt_val > (prop->mask >> __ffs(prop->mask)))
+			return -EINVAL;
 		*val = dt_val;
 		return 0;
 	}
@@ -104,7 +106,7 @@ static int aw99706_dt_property_lookup(const struct aw99706_dt_prop *prop,
 
 	*val = i;
 
-	return i == prop->tbl_size ? -1 : 0;
+	return i == prop->tbl_size ? -EINVAL : 0;
 }
 
 #define MIN_ILED_MAX	5000
@@ -116,11 +118,14 @@ aw99706_dt_property_iled_max_convert(const struct aw99706_dt_prop *prop,
 				     u32 dt_val, u8 *val)
 {
 	if (dt_val > MAX_ILED_MAX || dt_val < MIN_ILED_MAX)
-		return -1;
+		return -EINVAL;
+
+	if ((dt_val - MIN_ILED_MAX) % STEP_ILED_MAX)
+		return -EINVAL;
 
 	*val = (dt_val - MIN_ILED_MAX) / STEP_ILED_MAX;
 
-	return (dt_val - MIN_ILED_MAX) % STEP_ILED_MAX;
+	return 0;
 }
 
 static const struct aw99706_dt_prop aw99706_dt_props[] = {
-- 
2.43.0