Re: [RFC PATCH v1 3/4] media: v4l2-subdev: Store frame interval in subdev state

Laurent Pinchart
2023-11-27T10:38:59Z

Hi Tomi,

On Tue, Oct 24, 2023 at 10:40:29AM +0300, Tomi Valkeinen wrote:
> On 24/10/2023 10:38, Laurent Pinchart wrote:
> > On Tue, Oct 24, 2023 at 10:21:18AM +0300, Tomi Valkeinen wrote:
> >> On 24/10/2023 03:51, Laurent Pinchart wrote:
> >>> Subdev states store all standard pad configuration data, except for
> >>> frame intervals. Fix it by adding interval fields in the
> >>> v4l2_subdev_pad_config and v4l2_subdev_stream_config structures, with
> >>> corresponding accessor functions and a helper function to implement the
> >>> .get_frame_interval() operation.
> >>>
> >>> Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> >>> ---
> >>> drivers/media/v4l2-core/v4l2-subdev.c | 44 +++++++++++++++++++++
> >>> include/media/v4l2-subdev.h | 57 +++++++++++++++++++++++++++
> >>> 2 files changed, 101 insertions(+)
> >>>
> >>> diff --git a/drivers/media/v4l2-core/v4l2-subdev.c b/drivers/media/v4l2-core/v4l2-subdev.c
> >>> index c45d60a87701..518f2f35c68d 100644
> >>> --- a/drivers/media/v4l2-core/v4l2-subdev.c
> >>> +++ b/drivers/media/v4l2-core/v4l2-subdev.c
> >>> @@ -1618,6 +1618,29 @@ int v4l2_subdev_get_fmt(struct v4l2_subdev *sd, struct v4l2_subdev_state *state,
> >>> }
> >>> EXPORT_SYMBOL_GPL(v4l2_subdev_get_fmt);
> >>>
> >>> +int v4l2_subdev_get_frame_interval(struct v4l2_subdev *sd,
> >>> + struct v4l2_subdev_state *state,
> >>> + struct v4l2_subdev_frame_interval *fi)
> >>> +{
> >>> + struct v4l2_fract *interval;
> >>> +
> >>> + if (sd->flags & V4L2_SUBDEV_FL_STREAMS)
> >>> + interval = v4l2_subdev_state_get_stream_interval(state, fi->pad,
> >>> + fi->stream);
> >>> + else if (fi->pad < sd->entity.num_pads && fi->stream == 0)
> >>> + interval = v4l2_subdev_get_pad_interval(sd, state, fi->pad);
> >>> + else
> >>> + interval = NULL;
> >>> +
> >>> + if (!interval)
> >>> + return -EINVAL;
> >>> +
> >>> + fi->interval = *interval;
> >>> +
> >>> + return 0;
> >>> +}
> >>> +EXPORT_SYMBOL_GPL(v4l2_subdev_get_frame_interval);
> >>> +
> >>> int v4l2_subdev_set_routing(struct v4l2_subdev *sd,
> >>> struct v4l2_subdev_state *state,
> >>> const struct v4l2_subdev_krouting *routing)
> >>> @@ -1761,6 +1784,27 @@ v4l2_subdev_state_get_stream_compose(struct v4l2_subdev_state *state,
> >>> }
> >>> EXPORT_SYMBOL_GPL(v4l2_subdev_state_get_stream_compose);
> >>>
> >>> +struct v4l2_fract *
> >>> +v4l2_subdev_state_get_stream_interval(struct v4l2_subdev_state *state,
> >>> + unsigned int pad, u32 stream)
> >>> +{
> >>> + struct v4l2_subdev_stream_configs *stream_configs;
> >>> + unsigned int i;
> >>> +
> >>> + lockdep_assert_held(state->lock);
> >>> +
> >>> + stream_configs = &state->stream_configs;
> >>> +
> >>> + for (i = 0; i < stream_configs->num_configs; ++i) {
> >>> + if (stream_configs->configs[i].pad == pad &&
> >>> + stream_configs->configs[i].stream == stream)
> >>> + return &stream_configs->configs[i].interval;
> >>> + }
> >>> +
> >>> + return NULL;
> >>> +}
> >>> +EXPORT_SYMBOL_GPL(v4l2_subdev_state_get_stream_interval);
> >>> +
> >>> int v4l2_subdev_routing_find_opposite_end(const struct v4l2_subdev_krouting *routing,
> >>> u32 pad, u32 stream, u32 *other_pad,
> >>> u32 *other_stream)
> >>> diff --git a/include/media/v4l2-subdev.h b/include/media/v4l2-subdev.h
> >>> index 962b546d0e3b..363f9a8a084c 100644
> >>> --- a/include/media/v4l2-subdev.h
> >>> +++ b/include/media/v4l2-subdev.h
> >>> @@ -681,11 +681,13 @@ struct v4l2_subdev_ir_ops {
> >>> * @format: &struct v4l2_mbus_framefmt
> >>> * @crop: &struct v4l2_rect to be used for crop
> >>> * @compose: &struct v4l2_rect to be used for compose
> >>> + * @interval: frame interval
> >>> */
> >>> struct v4l2_subdev_pad_config {
> >>> struct v4l2_mbus_framefmt format;
> >>> struct v4l2_rect crop;
> >>> struct v4l2_rect compose;
> >>> + struct v4l2_fract interval;
> >>> };
> >>>
> >>> /**
> >>> @@ -697,6 +699,7 @@ struct v4l2_subdev_pad_config {
> >>> * @fmt: &struct v4l2_mbus_framefmt
> >>> * @crop: &struct v4l2_rect to be used for crop
> >>> * @compose: &struct v4l2_rect to be used for compose
> >>> + * @interval: frame interval
> >>> *
> >>> * This structure stores configuration for a stream.
> >>> */
> >>> @@ -708,6 +711,7 @@ struct v4l2_subdev_stream_config {
> >>> struct v4l2_mbus_framefmt fmt;
> >>> struct v4l2_rect crop;
> >>> struct v4l2_rect compose;
> >>> + struct v4l2_fract interval;
> >>> };
> >>>
> >>> /**
> >>> @@ -1199,6 +1203,26 @@ v4l2_subdev_get_pad_compose(struct v4l2_subdev *sd,
> >>> return &state->pads[pad].compose;
> >>> }
> >>>
> >>> +/**
> >>> + * v4l2_subdev_get_pad_interval - ancillary routine to get
> >>> + * &struct v4l2_subdev_pad_config->interval
> >>> + *
> >>> + * @sd: pointer to &struct v4l2_subdev
> >>> + * @state: pointer to &struct v4l2_subdev_state.
> >>> + * @pad: index of the pad in the &struct v4l2_subdev_state->pads array.
> >>> + */
> >>> +static inline struct v4l2_fract *
> >>> +v4l2_subdev_get_pad_interval(struct v4l2_subdev *sd,
> >>> + struct v4l2_subdev_state *state,
> >>> + unsigned int pad)
> >>> +{
> >>> + if (WARN_ON(!state))
> >>> + return NULL;
> >>> + if (WARN_ON(pad >= sd->entity.num_pads))
> >>> + pad = 0;
> >>> + return &state->pads[pad].interval;
> >>> +}
> >>> +
> >>> /*
> >>> * Temprary helpers until uses of v4l2_subdev_get_try_* functions have been
> >>> * renamed
> >>> @@ -1489,6 +1513,24 @@ v4l2_subdev_lock_and_get_active_state(struct v4l2_subdev *sd)
> >>> int v4l2_subdev_get_fmt(struct v4l2_subdev *sd, struct v4l2_subdev_state *state,
> >>> struct v4l2_subdev_format *format);
> >>>
> >>> +/**
> >>> + * v4l2_subdev_get_frame_interval() - Fill frame interval based on state
> >>> + * @sd: subdevice
> >>> + * @state: subdevice state
> >>> + * @fi: pointer to &struct v4l2_subdev_frame_interval
> >>> + *
> >>> + * Fill @fi->interval field based on the information in the @fi struct.
> >>> + *
> >>> + * This function can be used by the subdev drivers which support active state to
> >>> + * implement v4l2_subdev_pad_ops.get_frame_interval if the subdev driver does
> >>> + * not need to do anything special in their get_frame_interval op.
> >>
> >> What would the "something special" be? Can we instead just say that the
> >> framework will return the frame interval from the state for drivers that
> >> support active state (similar to get-routing)? Or perhaps that's not a
> >> wise thing to do for old operations...
> >
> > I've copied that text from v4l2_subdev_get_fmt(). I'm fine changing it,
> > if both say the same. If you send a patch to improve the documentation
> > of v4l2_subdev_get_fmt(), I'll update this patch :-)
>
> My point wasn't the docs, but changing the framework to return the frame
> interval directly from the state.

We don't do that for the .get_fmt() operation. I'm also fine considering
this, but I'd like to address both operations together, for consistency.

> Anyway, I was mostly just thinking out loud. Not part of this series anyway.