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

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Tomi,

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 :-)

-- 
Regards,

Laurent Pinchart