Since it's not necessarily very explicit why we need to zero some fields
in std_validate_compound, add a comment before the function to explain
why, which should help as a reminder.
Signed-off-by: Paul Kocialkowski <paul.kocialkow...@bootlin.com>
---
drivers/media/v4l2-core/v4l2-ctrls.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/drivers/media/v4l2-core/v4l2-ctrls.c
b/drivers/media/v4l2-core/v4l2-ctrls.c
index 76fa2db0e8fb..cd1ae016706f 100644
--- a/drivers/media/v4l2-core/v4l2-ctrls.c
+++ b/drivers/media/v4l2-core/v4l2-ctrls.c
@@ -1645,6 +1645,10 @@ static void std_log(const struct v4l2_ctrl *ctrl)
#define zero_padding(s) \
memset(&(s).padding, 0, sizeof((s).padding))
+/*
+ * Compound controls validation requires setting unused fields/flags to zero
+ * in order to properly detect unchanged controls with std_equal's memcmp.
+ */
static int std_validate_compound(const struct v4l2_ctrl *ctrl, u32 idx,
union v4l2_ctrl_ptr ptr)
{
--
2.22.0
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