Re: [PATCH v4 2/8] media: v4l2: abstract timeval handling in v4l2_buffer

From: Hans Verkuil
Date: Mon Nov 25 2019 - 10:52:23 EST

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On 11/11/19 9:38 PM, Arnd Bergmann wrote:
> As a preparation for adding 64-bit time_t support in the uapi,
> change the drivers to no longer care about the format of the
> timestamp field in struct v4l2_buffer.
>
> The v4l2_timeval_to_ns() function is no longer needed in the
> kernel after this, but there may be userspace code relying on
> it because it is part of the uapi header.

There is indeed userspace code that relies on this.

>
> Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
> ---
> drivers/media/common/videobuf2/videobuf2-v4l2.c | 4 ++--
> drivers/media/pci/meye/meye.c | 4 ++--
> drivers/media/usb/cpia2/cpia2_v4l.c | 4 ++--
> drivers/media/usb/stkwebcam/stk-webcam.c | 2 +-
> drivers/media/usb/usbvision/usbvision-video.c | 4 ++--
> drivers/media/v4l2-core/videobuf-core.c | 4 ++--
> include/linux/videodev2.h | 17 ++++++++++++++++-
> include/trace/events/v4l2.h | 2 +-
> include/uapi/linux/videodev2.h | 2 ++
> 9 files changed, 30 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/media/common/videobuf2/videobuf2-v4l2.c b/drivers/media/common/videobuf2/videobuf2-v4l2.c
> index 5a9ba3846f0a..9ec710878db6 100644
> --- a/drivers/media/common/videobuf2/videobuf2-v4l2.c
> +++ b/drivers/media/common/videobuf2/videobuf2-v4l2.c
> @@ -143,7 +143,7 @@ static void __copy_timestamp(struct vb2_buffer *vb, const void *pb)
> * and the timecode field and flag if needed.
> */
> if (q->copy_timestamp)
> - vb->timestamp = v4l2_timeval_to_ns(&b->timestamp);
> + vb->timestamp = v4l2_buffer_get_timestamp(b);
> vbuf->flags |= b->flags & V4L2_BUF_FLAG_TIMECODE;
> if (b->flags & V4L2_BUF_FLAG_TIMECODE)
> vbuf->timecode = b->timecode;
> @@ -476,7 +476,7 @@ static void __fill_v4l2_buffer(struct vb2_buffer *vb, void *pb)
>
> b->flags = vbuf->flags;
> b->field = vbuf->field;
> - b->timestamp = ns_to_timeval(vb->timestamp);
> + v4l2_buffer_set_timestamp(b, vb->timestamp);
> b->timecode = vbuf->timecode;
> b->sequence = vbuf->sequence;
> b->reserved2 = 0;
> diff --git a/drivers/media/pci/meye/meye.c b/drivers/media/pci/meye/meye.c
> index 0e61c81356ef..3a4c29bc0ba5 100644
> --- a/drivers/media/pci/meye/meye.c
> +++ b/drivers/media/pci/meye/meye.c
> @@ -1266,7 +1266,7 @@ static int vidioc_querybuf(struct file *file, void *fh, struct v4l2_buffer *buf)
> buf->flags |= V4L2_BUF_FLAG_DONE;
>
> buf->field = V4L2_FIELD_NONE;
> - buf->timestamp = ns_to_timeval(meye.grab_buffer[index].ts);
> + v4l2_buffer_set_timestamp(buf, meye.grab_buffer[index].ts);
> buf->sequence = meye.grab_buffer[index].sequence;
> buf->memory = V4L2_MEMORY_MMAP;
> buf->m.offset = index * gbufsize;
> @@ -1332,7 +1332,7 @@ static int vidioc_dqbuf(struct file *file, void *fh, struct v4l2_buffer *buf)
> buf->bytesused = meye.grab_buffer[reqnr].size;
> buf->flags = V4L2_BUF_FLAG_MAPPED | V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC;
> buf->field = V4L2_FIELD_NONE;
> - buf->timestamp = ns_to_timeval(meye.grab_buffer[reqnr].ts);
> + v4l2_buffer_set_timestamp(buf, meye.grab_buffer[reqnr].ts);
> buf->sequence = meye.grab_buffer[reqnr].sequence;
> buf->memory = V4L2_MEMORY_MMAP;
> buf->m.offset = reqnr * gbufsize;
> diff --git a/drivers/media/usb/cpia2/cpia2_v4l.c b/drivers/media/usb/cpia2/cpia2_v4l.c
> index 626264a56517..9d3d05125d7b 100644
> --- a/drivers/media/usb/cpia2/cpia2_v4l.c
> +++ b/drivers/media/usb/cpia2/cpia2_v4l.c
> @@ -800,7 +800,7 @@ static int cpia2_querybuf(struct file *file, void *fh, struct v4l2_buffer *buf)
> break;
> case FRAME_READY:
> buf->bytesused = cam->buffers[buf->index].length;
> - buf->timestamp = ns_to_timeval(cam->buffers[buf->index].ts);
> + v4l2_buffer_set_timestamp(buf, cam->buffers[buf->index].ts);
> buf->sequence = cam->buffers[buf->index].seq;
> buf->flags = V4L2_BUF_FLAG_DONE;
> break;
> @@ -907,7 +907,7 @@ static int cpia2_dqbuf(struct file *file, void *fh, struct v4l2_buffer *buf)
> buf->flags = V4L2_BUF_FLAG_MAPPED | V4L2_BUF_FLAG_DONE
> | V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC;
> buf->field = V4L2_FIELD_NONE;
> - buf->timestamp = ns_to_timeval(cam->buffers[buf->index].ts);
> + v4l2_buffer_set_timestamp(buf, cam->buffers[buf->index].ts);
> buf->sequence = cam->buffers[buf->index].seq;
> buf->m.offset = cam->buffers[buf->index].data - cam->frame_buffer;
> buf->length = cam->frame_size;
> diff --git a/drivers/media/usb/stkwebcam/stk-webcam.c b/drivers/media/usb/stkwebcam/stk-webcam.c
> index 21f90a887485..b22501f76b78 100644
> --- a/drivers/media/usb/stkwebcam/stk-webcam.c
> +++ b/drivers/media/usb/stkwebcam/stk-webcam.c
> @@ -1125,7 +1125,7 @@ static int stk_vidioc_dqbuf(struct file *filp,
> sbuf->v4lbuf.flags &= ~V4L2_BUF_FLAG_QUEUED;
> sbuf->v4lbuf.flags |= V4L2_BUF_FLAG_DONE;
> sbuf->v4lbuf.sequence = ++dev->sequence;
> - sbuf->v4lbuf.timestamp = ns_to_timeval(ktime_get_ns());
> + v4l2_buffer_set_timestamp(&sbuf->v4lbuf, ktime_get_ns());
>
> *buf = sbuf->v4lbuf;
> return 0;
> diff --git a/drivers/media/usb/usbvision/usbvision-video.c b/drivers/media/usb/usbvision/usbvision-video.c
> index cdc66adda755..15a423c5deb7 100644
> --- a/drivers/media/usb/usbvision/usbvision-video.c
> +++ b/drivers/media/usb/usbvision/usbvision-video.c
> @@ -687,7 +687,7 @@ static int vidioc_querybuf(struct file *file,
> vb->length = usbvision->curwidth *
> usbvision->curheight *
> usbvision->palette.bytes_per_pixel;
> - vb->timestamp = ns_to_timeval(usbvision->frame[vb->index].ts);
> + v4l2_buffer_set_timestamp(vb, usbvision->frame[vb->index].ts);
> vb->sequence = usbvision->frame[vb->index].sequence;
> return 0;
> }
> @@ -756,7 +756,7 @@ static int vidioc_dqbuf(struct file *file, void *priv, struct v4l2_buffer *vb)
> V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC;
> vb->index = f->index;
> vb->sequence = f->sequence;
> - vb->timestamp = ns_to_timeval(f->ts);
> + v4l2_buffer_set_timestamp(vb, f->ts);
> vb->field = V4L2_FIELD_NONE;
> vb->bytesused = f->scanlength;
>
> diff --git a/drivers/media/v4l2-core/videobuf-core.c b/drivers/media/v4l2-core/videobuf-core.c
> index 939fc11cf080..ab650371c151 100644
> --- a/drivers/media/v4l2-core/videobuf-core.c
> +++ b/drivers/media/v4l2-core/videobuf-core.c
> @@ -364,7 +364,7 @@ static void videobuf_status(struct videobuf_queue *q, struct v4l2_buffer *b,
> }
>
> b->field = vb->field;
> - b->timestamp = ns_to_timeval(vb->ts);
> + v4l2_buffer_set_timestamp(b, vb->ts);
> b->bytesused = vb->size;
> b->sequence = vb->field_count >> 1;
> }
> @@ -578,7 +578,7 @@ int videobuf_qbuf(struct videobuf_queue *q, struct v4l2_buffer *b)
> || q->type == V4L2_BUF_TYPE_SDR_OUTPUT) {
> buf->size = b->bytesused;
> buf->field = b->field;
> - buf->ts = v4l2_timeval_to_ns(&b->timestamp);
> + buf->ts = v4l2_buffer_get_timestamp(b);
> }
> break;
> case V4L2_MEMORY_USERPTR:
> diff --git a/include/linux/videodev2.h b/include/linux/videodev2.h
> index 16c0ed6c50a7..4086036e37d5 100644
> --- a/include/linux/videodev2.h
> +++ b/include/linux/videodev2.h
> @@ -56,7 +56,22 @@
> #ifndef __LINUX_VIDEODEV2_H
> #define __LINUX_VIDEODEV2_H
>
> -#include <linux/time.h> /* need struct timeval */
> +#include <linux/time.h>
> #include <uapi/linux/videodev2.h>
>
> +static inline u64 v4l2_buffer_get_timestamp(const struct v4l2_buffer *buf)
> +{
> + return buf->timestamp.tv_sec * NSEC_PER_SEC +
> + (u32)buf->timestamp.tv_usec * NSEC_PER_USEC;

Why the (u32) cast?

> +}
> +
> +static inline void v4l2_buffer_set_timestamp(struct v4l2_buffer *buf,
> + u64 timestamp)
> +{
> + struct timespec64 ts = ns_to_timespec64(timestamp);
> +
> + buf->timestamp.tv_sec = ts.tv_sec;
> + buf->timestamp.tv_usec = ts.tv_nsec / NSEC_PER_USEC;
> +}
> +

This does not belong in the public header. This is kernel specific,
so media/v4l2-common.h would be a good place.

Regards,

Hans

> #endif /* __LINUX_VIDEODEV2_H */
> diff --git a/include/trace/events/v4l2.h b/include/trace/events/v4l2.h
> index 83860de120e3..248bc09bfc99 100644
> --- a/include/trace/events/v4l2.h
> +++ b/include/trace/events/v4l2.h
> @@ -130,7 +130,7 @@ DECLARE_EVENT_CLASS(v4l2_event_class,
> __entry->bytesused = buf->bytesused;
> __entry->flags = buf->flags;
> __entry->field = buf->field;
> - __entry->timestamp = timeval_to_ns(&buf->timestamp);
> + __entry->timestamp = v4l2_buffer_get_timestamp(buf);
> __entry->timecode_type = buf->timecode.type;
> __entry->timecode_flags = buf->timecode.flags;
> __entry->timecode_frames = buf->timecode.frames;
> diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
> index 530638dffd93..74d3d522f3db 100644
> --- a/include/uapi/linux/videodev2.h
> +++ b/include/uapi/linux/videodev2.h
> @@ -1010,6 +1010,7 @@ struct v4l2_buffer {
> };
> };
>
> +#ifndef __KERNEL__
> /**
> * v4l2_timeval_to_ns - Convert timeval to nanoseconds
> * @ts: pointer to the timeval variable to be converted
> @@ -1021,6 +1022,7 @@ static inline __u64 v4l2_timeval_to_ns(const struct timeval *tv)
> {
> return (__u64)tv->tv_sec * 1000000000ULL + tv->tv_usec * 1000;
> }
> +#endif
>
> /* Flags for 'flags' field */
> /* Buffer is mapped (flag) */
>

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Next in thread: Arnd Bergmann: "Re: [PATCH v4 2/8] media: v4l2: abstract timeval handling in v4l2_buffer"
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