On Thu, Jul 14, 2022 at 4:41 PM Tomi Valkeinen
<tomi.valkeinen@xxxxxxxxxxxxxxxx> wrote:
>
> Hi,
>
> On 07/07/2022 13:27, Tomasz Figa wrote:
> > Hi Tomi, Laurent,
> >
> > On Tue, Mar 01, 2022 at 06:11:54PM +0200, Tomi Valkeinen wrote:
> >> From: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
> >>
> >> Add a helper function to translate streams between two pads of a subdev,
> >> using the subdev's internal routing table.
> >>
> >
> > Thanks for the patch! Please see my comments inline.
> >
> >> Signed-off-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
> >> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@xxxxxxxxxxxxxxxx>
> >> ---
> >> drivers/media/v4l2-core/v4l2-subdev.c | 25 +++++++++++++++++++++++++
> >> include/media/v4l2-subdev.h | 23 +++++++++++++++++++++++
> >> 2 files changed, 48 insertions(+)
> >>
> >> diff --git a/drivers/media/v4l2-core/v4l2-subdev.c b/drivers/media/v4l2-core/v4l2-subdev.c
> >> index e30338a53088..6a9fc62dacbf 100644
> >> --- a/drivers/media/v4l2-core/v4l2-subdev.c
> >> +++ b/drivers/media/v4l2-core/v4l2-subdev.c
> >> @@ -1529,6 +1529,31 @@ v4l2_subdev_state_get_opposite_stream_format(struct v4l2_subdev_state *state,
> >> }
> >> EXPORT_SYMBOL_GPL(v4l2_subdev_state_get_opposite_stream_format);
> >>
> >> +u64 v4l2_subdev_state_xlate_streams(const struct v4l2_subdev_state *state,
> >> + u32 pad0, u32 pad1, u64 *streams)
> >> +{
> >> + const struct v4l2_subdev_krouting *routing = &state->routing;
> >> + struct v4l2_subdev_route *route;
> >> + u64 streams0 = 0;
> >> + u64 streams1 = 0;
> >> +
> >> + for_each_active_route(routing, route) {
> >> + if (route->sink_pad == pad0 && route->source_pad == pad1 &&
> >> + (*streams & BIT(route->sink_stream))) {
> >> + streams0 |= BIT(route->sink_stream);
> >> + streams1 |= BIT(route->source_stream);
> >> + }
> >> + if (route->source_pad == pad0 && route->sink_pad == pad1 &&
> >> + (*streams & BIT(route->source_stream))) {
> >> + streams0 |= BIT(route->source_stream);
> >> + streams1 |= BIT(route->sink_stream);
> >> + }
> >> + }
> >> +
> >> + *streams = streams0;
> >> + return streams1;
> >> +}
> >> +
> >> int v4l2_subdev_get_fmt(struct v4l2_subdev *sd, struct v4l2_subdev_state *state,
> >> struct v4l2_subdev_format *format)
> >> {
> >> diff --git a/include/media/v4l2-subdev.h b/include/media/v4l2-subdev.h
> >> index 1eced0f47296..992debe116ac 100644
> >> --- a/include/media/v4l2-subdev.h
> >> +++ b/include/media/v4l2-subdev.h
> >> @@ -1497,6 +1497,29 @@ struct v4l2_mbus_framefmt *
> >> v4l2_subdev_state_get_opposite_stream_format(struct v4l2_subdev_state *state,
> >> u32 pad, u32 stream);
> >>
> >> +/**
> >> + * v4l2_subdev_state_xlate_streams() - Translate streams from one pad to another
> >> + *
> >> + * @state: Subdevice state
> >> + * @pad0: The first pad
> >> + * @pad1: The second pad
> >> + * @streams: Streams bitmask on the first pad
> >> + *
> >> + * Streams on sink pads of a subdev are routed to source pads as expressed in
> >> + * the subdev state routing table. Stream numbers don't necessarily match on
> >> + * the sink and source side of a route. This function translates stream numbers
> >> + * on @pad0, expressed as a bitmask in @streams, to the corresponding streams
> >> + * on @pad1 using the routing table from the @state. It returns the stream mask
> >> + * on @pad1, and updates @streams with the streams that have been found in the
> >> + * routing table.
> >> + *
> >> + * @pad0 and @pad1 must be a sink and a source, in any order.
> >> + *
> >> + * Return: The bitmask of streams of @pad1 that are routed to @streams on @pad0.
> >
> > It might be just me, but somehow I associate "translate" with turning a
> > name from one namespace into a corresponding name from another
> > namespace. In this case I initially assumed that this function is
> > supposed to accept stream IDs from pad0 and return corresponding
> > stream IDs from pad1. However, it looks like this is move like - "tell
> > me which streams on pad1 are connected to the given pad0 streams". Is
> > this correct?
>
> So is your point that as the function returns a bitmask, and not a
> mapping of the stream IDs, this is not a translate function?
Yep.
>
> > If yes, maybe v4l2_subdev_state_get_routed_streams() be a better name?
>
> I think this name would also fit quite well for a function that returns
> a mapping of the streams. So... I don't have a strong opinion on this.
> To me, neither the current name nor the proposed one clearly explains
> alone what the function does.
Well, since it's a kernel function, it probably can be renamed later.
Anyway, I forgot to place "nit:" before the comment. It's not really a
strong opinion from me either.
Best regards,
Tomasz
