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SubjectRe: [PATCH v5 00/39] i.MX Media Driver
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On Mon, 2017-03-20 at 15:43 +0000, Russell King - ARM Linux wrote:
> On Mon, Mar 20, 2017 at 02:20:16PM +0100, Philipp Zabel wrote:
> > To set and read colorimetry information:
> > https://patchwork.linuxtv.org/patch/39350/
>
> Thanks, I've applied all four of your patches, but there's a side effect
> from that. Old media-ctl (modified by me):
>
> - entity 53: imx219 0-0010 (2 pads, 2 links)
> type V4L2 subdev subtype Unknown flags 0
> device node name /dev/v4l-subdev9
> pad0: Source
> [fmt:SRGGB8/816x616 field:none
> frame_interval:1/25]
> -> "imx6-mipi-csi2":0 [ENABLED]
> pad1: Sink
> [fmt:SRGGB10/3280x2464 field:none
> crop.bounds:(0,0)/3280x2464
> crop:(0,0)/3264x2464
> compose.bounds:(0,0)/3264x2464
> compose:(0,0)/816x616]
> <- "imx219 pixel 0-0010":0 [ENABLED,IMMUTABLE]
>
> New media-ctl:
>
> - entity 53: imx219 0-0010 (2 pads, 2 links)
> type V4L2 subdev subtype Unknown flags 0
> device node name /dev/v4l-subdev9
> pad0: Source
> [fmt:SRGGB8_1X8/816x616@1/25 field:none colorspace:srgb xfer:srgb]
> -> "imx6-mipi-csi2":0 [ENABLED]
> pad1: Sink
> <- "imx219 pixel 0-0010":0 [ENABLED,IMMUTABLE]
>
> It looks like we successfully retrieve the frame interval for pad 0
> and print it, but when we try to retrieve the frame interval for pad 1,
> we get EINVAL (because that's what I'm returning, but I'm wondering if
> that's the correct thing to do...) and that prevents _all_ format
> information being output.

According to the documentation [1], you are doing the right thing:

The struct v4l2_subdev_frame_interval pad references a non-existing
pad, or the pad doesn’t support frame intervals.

But v4l2_subdev_call returns -ENOIOCTLCMD if the g_frame_interval op is
not implemented at all, which is turned into -ENOTTY by video_usercopy.

[1] https://linuxtv.org/downloads/v4l-dvb-apis/uapi/v4l/vidioc-subdev-g-frame-interval.html#return-value

> Maybe something like the following would be a better idea?
>
> utils/media-ctl/media-ctl.c | 10 +++++-----
> 1 file changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/utils/media-ctl/media-ctl.c b/utils/media-ctl/media-ctl.c
> index f61963a..a50a559 100644
> --- a/utils/media-ctl/media-ctl.c
> +++ b/utils/media-ctl/media-ctl.c
> @@ -81,22 +81,22 @@ static void v4l2_subdev_print_format(struct media_entity *entity,
> struct v4l2_mbus_framefmt format;
> struct v4l2_fract interval = { 0, 0 };
> struct v4l2_rect rect;
> - int ret;
> + int ret, err_fi;
>
> ret = v4l2_subdev_get_format(entity, &format, pad, which);
> if (ret != 0)
> return;
>
> - ret = v4l2_subdev_get_frame_interval(entity, &interval, pad);
> - if (ret != 0 && ret != -ENOTTY)
> - return;
> + err_fi = v4l2_subdev_get_frame_interval(entity, &interval, pad);

Not supporting frame intervals doesn't warrant a visible error message,
I think -EINVAL should also be ignored above, if the spec is to be
believed.

>
> printf("\t\t[fmt:%s/%ux%u",
> v4l2_subdev_pixelcode_to_string(format.code),
> format.width, format.height);
>
> - if (interval.numerator || interval.denominator)
> + if (err_fi == 0 && (interval.numerator || interval.denominator))
> printf("@%u/%u", interval.numerator, interval.denominator);
> + else if (err_fi != -ENOTTY)
> + printf("@<error: %s>", strerror(-err_fi));

Or here.

>
> if (format.field)
> printf(" field:%s", v4l2_subdev_field_to_string(format.field));
>
>

regards
Philipp

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