On Tue, Feb 28, 2017 at 10:14:37PM +0100, Arnd Bergmann wrote:
> tw5864_frameinterval_get() only initializes its output when it successfully
> identifies the video standard in tw5864_input. We get a warning here because
> gcc can't always track the state if initialized warnings across a WARN()
> macro, and thinks it might get used incorrectly in tw5864_s_parm:
>
> media/pci/tw5864/tw5864-video.c: In function 'tw5864_s_parm':
> media/pci/tw5864/tw5864-video.c:816:38: error: 'time_base.numerator' may be used uninitialized in this function [-Werror=maybe-uninitialized]
> media/pci/tw5864/tw5864-video.c:819:31: error: 'time_base.denominator' may be used uninitialized in this function [-Werror=maybe-uninitialized]
>
> Using dev_warn() instead of WARN() avoids the __branch_check__() in
> unlikely and lets the compiler see that the initialization is correct.
>
> Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
Thanks for the patch.
Acked-by: Andrey Utkin <andrey.utkin@xxxxxxxxxxxxxxxxxxx>
See the note below.
> ---
> drivers/media/pci/tw5864/tw5864-video.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/media/pci/tw5864/tw5864-video.c b/drivers/media/pci/tw5864/tw5864-video.c
> index 9421216bb942..4d9994a11c22 100644
> --- a/drivers/media/pci/tw5864/tw5864-video.c
> +++ b/drivers/media/pci/tw5864/tw5864-video.c
> @@ -717,6 +717,8 @@ static void tw5864_frame_interval_set(struct tw5864_input *input)
> static int tw5864_frameinterval_get(struct tw5864_input *input,
> struct v4l2_fract *frameinterval)
> {
> + struct tw5864_dev *dev = input->root;
> +
> switch (input->std) {
> case STD_NTSC:
> frameinterval->numerator = 1001;
> @@ -728,8 +730,8 @@ static int tw5864_frameinterval_get(struct tw5864_input *input,
> frameinterval->denominator = 25;
> break;
> default:
> - WARN(1, "tw5864_frameinterval_get requested for unknown std %d\n",
> - input->std);
> + dev_warn(&dev->pci->dev, "tw5864_frameinterval_get requested for unknown std %d\n",
> + input->std);
> return -EINVAL;
> }
Looks good, though, arguably, it could fit 80 columns better if you put
the string literal to separate line.
