Hello 

When passing strings which has NULL in between, low level driver will not get 
full strings. 
Our typical use case is kernel level muxer, where "PMT" descriptor  is passed 
as strings, which will have NULL in between. 

In this case V4L2, copies the whole size and passing only stings to low level 
driver. 
If V4L2 sends size along with strings to low level driver then it will fix the 
problem and let low level driver to decide whether they want to use
size of strings or size. 

Below patch is proposed to fix such issues. 

diff --git a/drivers/media/v4l2-core/v4l2-ctrls.c 
b/drivers/media/v4l2-core/v4l2-ctrls.c
index 7e38d59..bd3dc67 100644
--- a/drivers/media/v4l2-core/v4l2-ctrls.c
+++ b/drivers/media/v4l2-core/v4l2-ctrls.c
@@ -1166,10 +1166,12 @@ static int user_to_new(struct v4l2_ext_control *c,
        u32 size;
 
        ctrl->is_new = 1;
+       ctrl->size = c->size;
        switch (ctrl->type) {
        case V4L2_CTRL_TYPE_INTEGER64:
                ctrl->val64 = c->value64;
                break;
diff --git a/include/media/v4l2-ctrls.h b/include/media/v4l2-ctrls.h
index 47ada23..75ec59c 100644
--- a/include/media/v4l2-ctrls.h
+++ b/include/media/v4l2-ctrls.h
@@ -152,6 +152,7 @@ struct v4l2_ctrl {
                char *string;
        };
        void *priv;
+       u32 size;
 };
 
 /** struct v4l2_ctrl_ref - The control reference.



Regards
Udit
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