Re: [PATCH v2 07/10] media/usb/pvrusb2: Support for V4L2_CTRL_WHICH_DEF_VAL

From: Mike Isely
Date: Fri Aug 21 2015 - 22:00:24 EST



The code you've added is carefully checking the return pointer from
pvr2_hdw_get_ctrl_v4l() yet the original code did not operate this way.
The result is that now there's this "unbalanced" effect where it appears
that the validity of the pvr2_ctrl instance is only checked on one side
of the if-statement. I would recommend instead to elevate the call to
pvr2_hdw_get_ctrl_v4l() out of the if-statement - since in both cases
it's being called the same way both times. Then do the validity check
in that one spot and that simplifies the if-statement all the way down
to choosing between pvr2_ctrl_get_value() vs pvr2_ctrl_get_def().

It's not a correctness comment; what you have should work fine. So I'm
ack'ing this in any case:

Acked-By: Mike Isely <isely@xxxxxxxxx>

But you can do the above pretty easily & safely, and simplify it a bit
further.

-Mike


On Fri, 21 Aug 2015, Ricardo Ribalda Delgado wrote:

> This driver does not use the control infrastructure.
> Add support for the new field which on structure
> v4l2_ext_controls
>
> Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@xxxxxxxxx>
> ---
> drivers/media/usb/pvrusb2/pvrusb2-v4l2.c | 17 ++++++++++++++++-
> 1 file changed, 16 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/media/usb/pvrusb2/pvrusb2-v4l2.c b/drivers/media/usb/pvrusb2/pvrusb2-v4l2.c
> index 1c5f85bf7ed4..43b2f2214798 100644
> --- a/drivers/media/usb/pvrusb2/pvrusb2-v4l2.c
> +++ b/drivers/media/usb/pvrusb2/pvrusb2-v4l2.c
> @@ -628,6 +628,7 @@ static int pvr2_g_ext_ctrls(struct file *file, void *priv,
> struct pvr2_v4l2_fh *fh = file->private_data;
> struct pvr2_hdw *hdw = fh->channel.mc_head->hdw;
> struct v4l2_ext_control *ctrl;
> + struct pvr2_ctrl *cptr;
> unsigned int idx;
> int val;
> int ret;
> @@ -635,8 +636,18 @@ static int pvr2_g_ext_ctrls(struct file *file, void *priv,
> ret = 0;
> for (idx = 0; idx < ctls->count; idx++) {
> ctrl = ctls->controls + idx;
> - ret = pvr2_ctrl_get_value(
> + if (ctls->which == V4L2_CTRL_WHICH_DEF_VAL) {
> + cptr = pvr2_hdw_get_ctrl_v4l(hdw, ctrl->id);
> + if (cptr)
> + pvr2_ctrl_get_def(cptr, &val);
> + else
> + ret = -EINVAL;
> +
> +
> + } else
> + ret = pvr2_ctrl_get_value(
> pvr2_hdw_get_ctrl_v4l(hdw, ctrl->id), &val);
> +
> if (ret) {
> ctls->error_idx = idx;
> return ret;
> @@ -658,6 +669,10 @@ static int pvr2_s_ext_ctrls(struct file *file, void *priv,
> unsigned int idx;
> int ret;
>
> + /* Default value cannot be changed */
> + if (ctls->which == V4L2_CTRL_WHICH_DEF_VAL)
> + return -EINVAL;
> +
> ret = 0;
> for (idx = 0; idx < ctls->count; idx++) {
> ctrl = ctls->controls + idx;
>

--

Mike Isely
isely @ isely (dot) net
PGP: 03 54 43 4D 75 E5 CC 92 71 16 01 E2 B5 F5 C1 E8
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