On 16/03/2022 13:26, Jacopo Mondi wrote:
Hi Tomi,
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.
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;
I'll probably learn how this is used later, but I found it hard to
immagine how the returned mask should be used.
To a sink stream mask that contains multiple streams a source maks
with multiple entries will be associated
In example, the sink stream mask might look lik
sink_stream_mask = {1, 0, 1, 0}
So we are interested in translating stream 0 and 2
Assume 0->4 and 2->1 in the routing tabe, the resulting source stream
mask will be
source_stream_mask = {1, 0, 0, 1}
How should the caller know what stream goes where ?
The use case for the function is for cases where all the streams go from
one pad to another. Probably the main use is in subdevs with a single
source and sink pad. This makes it easy to implement enable_streams()
op: you just basically call v4l2_subdev_state_xlate_streams() to get the
streams on the other side, and call v4l2_subdev_enable_streams(). Here's
a version from ub913:
static int ub913_enable_streams(struct v4l2_subdev *sd,
struct v4l2_subdev_state *state, u32 pad,
u64 streams_mask)
{
struct ub913_data *priv = sd_to_ub913(sd);
struct media_pad *remote_pad;
u64 sink_streams;
int ret;
if (streams_mask & priv->enabled_source_streams)
return -EALREADY;
sink_streams = v4l2_subdev_state_xlate_streams(
state, UB913_PAD_SOURCE, UB913_PAD_SINK, &streams_mask);
remote_pad = media_entity_remote_pad(&priv->pads[UB913_PAD_SINK]);
ret = v4l2_subdev_enable_streams(priv->source_sd, remote_pad->index,
sink_streams);
if (ret)
return ret;
priv->enabled_source_streams |= streams_mask;
return 0;
}
+}
+
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
Could we stress out that pads are on the same entity and this is not
meant to translate over media links ? Is this necessary ?
The streams on both sides of a link are identical, so there can be no
translation in that case.
The doc below explains the use, I'd rather not try to squeeze in a
longer explanation in the title.
But I think we should emphasize that this only makes sense on a simple
routing case.
+ *
+ * @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.
+ */
+u64 v4l2_subdev_state_xlate_streams(const struct v4l2_subdev_state *state,
+ u32 pad0, u32 pad1, u64 *streams);
+
/**
* v4l2_subdev_get_fmt() - Fill format based on state
* @sd: subdevice
--
2.25.1
